As has been mentioned before, the LS engines were not expressly designed to go between the frame rails of the first- or second-generation F-Body. Every modern LS engine is fuel injected while every early F-Body car carried a carbureted engine. Fuel injection has many different requirements than carbureted engines. To run the Efisystem on an F-Body requires installation of more fuel system plumbing and either an internal or external electric fuel pump for the injection system. You also need to integrate the wiring into the main harness and install the drive-by-wire pedal. Even with these challenges, LS engines have been effectively installed in the 1967–1981 F-Body chassis and have delivered phenomenal performance.
This Tech Tip is From the Full Book, SWAP LS ENGINES INTO CAMAROS & FIREBIRDS: 1967-1981. For a comprehensive guide on this entire subject you can visit this link:
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The early Gen III engines from 1997 to 1998 and some 1999 engines used a return fuel line system while the 1999 and newer LS engines used a returnless fuel system. If you are installing a later-style Gen III or Gen IV engine, you don’t have to route a fuel line back to the tank. If you’re installing an LS with a return fuel line system, a regulator is installed between the fuel rail and tank to provide consistent fuel pressure. Then hoses must be run to a 3/8-inch supply fitting and 5/16-inch return fitting on the fuel rails.
Throughout this chapter, I show you various ways to build a fuel system for your LS-equipped F-Body car. I discuss the use of stock gas tank modifications all the way up to a custom-built stainless gas tank with a trick off-the-shelf pump. Of course there are many ways to complete the task and I can only show a few of them. This should help you decide the direction of your build.
By today’s modern fuel injection standards, the first two iterations of the F-Body and its fuel system were crude and rudimentary. The stock F-Body used a mechanical fuel pump, which was driven off the camshaft, and it drew fuel from the gas tank to the engine. In addition, the LS engine has far greater fuel pressure requirements than the original carburetorequipped F-Body. Carburetors were fairly reliable and easy to fix, but they featured a static setup and didn’t change to accommodate varying conditions. They were prone to carbon build up and tended to blow out power valves if the car wasn’t driven properly. Today, the fuel delivery system no longer requires engine power to drive the fuel pump and requires an electric pump to delivery fuel needs. The old system only needed a paltry 8 to 10 psi at the carburetor while an LS engine with an Efineeds a constant 58 psi at the fuel rail. This means that it’s a necessity to upgrade your fuel system with an electric pump and a fuel pressure regulator. This means more forethought and some blueprinting of the new fuel system in your F-Body.
A fuel system needs to be planned out prior to purchases being made and brackets formed. A solid fuel delivery system also requires a properly wired system. This means that you have to ask yourself what your plans are for your car so you can buy the correct combination of parts. One question that many folks face is, “Am I going to upgrade in the near future?” If the answer is yes, you might want to step up to a slightly better system to plan for the long haul.
A carbureted system needs roughly 8 psi to operate well under idle and under heavy loads. Unfortunately, the newer engines with EFI (and this includes the LS engines) require much greater fuel pressure and fuel system sophistication. The key number to remember here is 58 psi. If you are running a stock or mildly upgraded LS engine, this is all you need in terms of fuel delivery. If you are running an LSA or LS9, you might need to step up to a much better fuel delivery system that requires more than 58 psi. However, 58 psi is sufficient for most LS engines turning out 400 to 700 hp.
Fuel injectors require high pressure to deliver fuel into the combustion chamber in a microsecond. In order for the injectors to do their job, they need a constant supply of high-pressure fuel in sufficient quantities (flow rate) or the engine ceases running. In addition, the injectors need this much pressure to keep an even and consistent spray pattern. The system requires a constant high-pressure fuel to be available at all times. By comparison, a carburetor is vacuum operated and doesn’t require high pressure to mix air and fuel together to feed the engine.
I went to Carl Casanova, the guru of fuel delivery, to gain insight and advice for planning and installing a fuel system. Carl has been known around the pro-touring and hot rodding fuel delivery arena for quite some time. You probably have seen his shiny red Gen I in multiple articles in various print and online publications. He teamed up with Hector Guerrero at Rick’s Tanks to make a system that functions like factory equipment, with easy installation and the reliability of a rental car.
When it comes to fuel pumps, there are two basic kinds: in-tank and external. Both systems have advantages and disadvantages. The intank pumps tend to run quieter and cooler because they are immersed in fuel inside the tank. They also tend to perform at higher pressures. The trade-off is that they are often more complicated to install and relatively costly. To modify a stock system to work with an in-tank pump requires a greater investment of time and potentially more money.
To make your system an in-tank setup, you need the pump submerged in the tank as deep as possible but maintain a strong fuel feed. You don’t want it choked off because of improper mounting. You need to mount the system carefully and properly for your particular setup and needs. This means you have to find a creative mounting system that is not only fuel resistant but also sturdy enough to handle a bit of abuse. Adequate tank pressure is necessary to keep the pressure up between the pump and the fuel line.
External pumps make the job a lot easier to install or replace in case of a failure because you can simply access the external pump where it’s mounted to the chassis. With an intank system, the gas tank needs to be drained and dropped and then the pump has to be extracted from the tank. In-tank pumps are less expensive to purchase, but if you need to change a pump it costs a lot more in the long run. External pumps are typically noisier because they lack fuel to dampen the sound and they are exposed to the elements. In addition, the pump can transmit vibrations through the chassis to create noise.
The best and most logical place to put an external pump is as close to the gas tank as possible and at or below the fuel level. These pumps work best as “pushers” of fuel, rather than “pullers” of fuel. Pump life is extended because gravity is used to draw fuel to the pump and therefore a reduced load is placed on the pump to enhance longevity.
The other major problem with an external pump is that the fuel line is only pressurized after the pump. This means that the system relies on gravity to feed the pump. These pumps can provide some suction but should be gravity fed for optimal results. This means that your system can lose its siphon under hard cornering. If you plan to do any hardcore racing or severe lateral-g’s, you should really look into an in-tank system.
Matching the fuel pump to the engine’s fuel demands is vital. I recommend determining the amount of fuel needed for the engine, adding 10 percent for safety, then choosing the fuel pump that best matches the fueling need. A 255 lph fuel pump is usually a good starting point for comparison.
Determining which fuel pump is right for you requires a number of steps. First, you need to determine your engine’s horsepower and torque target. It’s typically safe to aim high here because it’s better to have more fuel pump capacity rather than not enough. Second is finding the engine fuel efficiency and third is finding the maximum fuel pressure and flow volume you’ll be running. Finally, you need to know the available voltage under load from the engine and flow volume at that particular voltage.
I spoke with an Aeromotive tech specialist about engine fuel efficiency, and he informed me that typically naturally-aspirated engines make roughly between .4 and .5 lb/ hp/hr (pound per horsepower per hour). The tech strongly recommended engine dyno testing to determine your actual efficiency number, but these are good starting points. Engines with a nitrous addition often develop .5 to .6 lb/hp/hr and those with boosted applications are usually least efficient at ranges from .6 to .75 lb/hp/hr.
So, for example, if I used a 500- hp naturally-aspirated engine I would multiply 500 by .4 and get 200 pounds, which would be the expected fuel pump requirement. However, if I used a 500-hp engine that was boosted, I could potentially multiply that by .75 and get 375 pounds of fuel pump requirement. Aeromotive also informed me that this also plays a big factor in injector choice. Normally most engine builders like to use a duty cycle of .8, which gives them a window of 10 percent for unexpected occurrences.
Therefore, using our example of 500 hp and a naturally aspirated engine, I would get something like this:
Next is finding the base fuel pressure for the engine, and of course, fuel system requirements change for boosted or nitrous applications. As pressure goes up, often pump volume goes down. It is important to check the fuel pump’s specifications and read the flow charts for accurate pressure ranges. (If this is something that you find challenging, the Aeromotive tech line is a great place for asking questions about fuel pumps.) In the case of my build I knew going in that my LS3 as well as most LS applications require a constant 58 psi for the engine to run optimally throughout the power band.
Finally, you need to consider voltage. If the pump does not have the required power it under performs and does not run at peak efficiency. Higher voltage means that it increases power output so it is crucial to match your alternator’s output with the fuel pump you are using to complement the entire system.
The following focuses primarily on fuel-injected setups, as those seem to have the most confusion. If you plan to run a carbureted LS engine, a lot of it doesn’t apply.
External Fuel Pump Assembly
Several approaches can be used to install a fuel system. Often the most practical way to do this is with an external pump assembly. A few key features are critical when constructing a new delivery system. The best way to do this is to plan well ahead of your build so you don’t end up having to redo it or buying the wrong parts. Remembering that an external pump works best as a pusher of fuel (not a puller) commands your next moves. You certainly want gravity to feed your pump, so it’s best to place the pump as close to the tank sump as possible.
A typical setup consists of a prefilter, pump, after-filter, fuel pressure regulator, return line, and feed line that is typically regulated by a vacuum source coming from the engine. The location of these components is dependent on available space. A lot of folks run the regulator on the firewall for easy access and that’s typically a good idea. Keep in mind that you need to run a vacuum line and a return line back to the fuel tank. Some racing circuits do not allow this so you might have to get creative. For most street drives the firewall is the most useful, accessible, and logical place to put the regulator.
Because external pumps are “pushers,” you want to mount the pump as close to the gas tank as possible. The most efficient way is to build a bracket that mounts between the front of the fuel tank and the rear axle assembly and rear suspension. Keep in mind that exhaust and suspension become major factors when you stray from stock components. For example, in this build adding an external pump assembly is impractical as the rear suspension is far too cumbersome to work around.
Fuel Level Sending Units
A lot of sending units are on the market right now. The key is to determine what gauge you’ll be using. Almost all GM gauges and fuel level units use a 0- to 90-ohm reading. Virtually any company can supply you with a gauge that fits this criteria. The important factor here is that you correctly match the gauge to the fuel level unit in terms of ohms. Wiring is fairly straightforward; simple ground and positive wires usually do the trick.
I cannot emphasize this part enough: It is crucial that if you choose to run an external pump it is essential to use a pre-filter to catch debris before it gets to the pump. It’s common knowledge to run a filter after the pump. It is also important to purchase the correct high-pressure filters as well; the old carburetor filters give out too easily for these kinds of pressures.
A neat trick for systems running a return line (which is most of them) is to run a C5 Corvette external fuel filter and regulator. If you have an LS engine that is 500 hp or less (which is probably stretching the limits of the C5 fuel pressure regulator), you might want to seriously consider GM PN 10299146. Not only does it act as a regulator designed specifically for LS engines, it does triple duty as a filter and provides a return line to keep the number of pressured lines to a minimum. Again, this has the standard 3/8-inch quick-connection for the inlet, and a 5/16-inch quickconnection on the return side. So make sure to plan on purchasing the correct number of adapters for your project.
Hose and Fittings
You need to use the correct hose for the correct component; otherwise you risk hose failure and a fire. Not all fuel lines are created equal. Fuel lines rated for carburetors are inadequate for the pressure of fuel-injection systems. Typically, an EFI system applies triple the pressure to the hoses as fuel hoses for carburetors. In fact, a carburetor fuel pressure is 8 to 11 psi while the fuel pressure for an LS3 is 60 psi and most LS engines have 40 to 60 psi. If you rupture a fuel line, it can easily create a fire and your car can potentially burn to the ground. You must use hoses that are rated to handle the pressure from your fuel system. You must use the correct fuel-injection rubber hose or, even better, braided fuel line.
I recommend using braided (PTFE) lines over rubber lines for a few simple reasons. They prevent premature wear by being much more durable and resist wear better than the rubber lines. In addition, they are less likely to kink compared to rubber lines. It might be advantageous to use hard lines for long runs under the car and add a few adapters. I prefer to keep the system as basic as possible (in this build I used one long piece of -8AN braided fuel line from the pump straight to the fuel rail). You can use either -6AN or -8AN fittings for mild to medium applications.
When I saw the quick-connect ends of the fuel pump and the fuel rails on the stock LS engine, I thought I had run into a big compatibility issue. Thankfully companies have come up with reliable adapters to help fit stock fuel lines to AN-sized fittings and hoses. Here, for example, I used Russell’s (PN 644000) to connect the fuel pump to a -8AN fuel line (mine are black). A -6AN line is fine up to about 700-hp engines; bigger than that and you might want to step up to -8AN.
Stock Fuel Tank Replacement
Removing a stock tank is not difficult and I’ve included a couple of quick tips to help you make the job a lot less messy. Depending on your vehicle, you might have a two-piece downspout, such as on my 1968 test car, or it could be like the 1969 version where the spout is built in. With either downspout, disconnecting the spout from the car is the first priority. The fuel line connections to the tank come next (these are located through the rear passenger-side wheel well on my car).
Make sure you remove all the old gas or run the risk of getting a lap full of nasty old gasoline. Siphoning the tank is fairly easy but can be a pain. Doing this lightens the load when you pull the tank out.
Two bolts hold the tank between the rear bumper and the trunk. A deep-well 9/16-inch socket does the trick. Make sure to remove the electrical connectors as you slowly lower the tank. I used a board and a jack to guide the tank out of its cocoon.
Fuel Tank Removal and Installation
To remove the old gas tank in a 1968 Camaro I first have to remove the fuel filler neck cover to reveal the rubber housing protecting the filler neck. On the 1969, the fi ller neck is attached to the tank. On the 1968, I used a socket to unbolt the necessary pieces and slid them out of the way.
Use a 5/16-inch socket and ratchet to remove the four outer bolts that anchor the fuel filler neck.
Once the bolts have been removed, the old filler neck is easily lifted from the car.
Remove the screws or fasteners that secure the license plate. Once removed, you have access to the two clamps that hold the gas tank and filler neck together. This is also a good place to access the tan fuel gauge wire.
Before lowering the tank, remove any attachments, such as the ground wire, gauge lead wire, and fuel feed line, which is located right behind the passenger-side rear tire. Typically, a small wormgear clamp is all that holds the fuel tube in place. Be prepared to cut it off if it’s cracked or the rubber has gone bad.
Use a deep-well 9/16-inch socket to remove the two nuts that hold the tank straps in place. Even though the tank had been replaced in the past five years, it was still a difficult job to remove the large and unwieldy gas tank. The nuts and bolts are exposed to the elements so these fasteners typically rust and therefore it’s much more difficult to remove them. Using a thread lubricant to spray the nuts makes the job much easier.
I recommend using a jack and a flat board to support, lower, and remove the tank from the chassis. Raise the jack high enough so the board makes even contact with the bottom of the tank. Remove the nuts from the tank straps and balance the tank on the jack. Slowly lower the jack until the gas tank is close to the floor and can be properly moved. Turns out I had about 3 to 4 gallons of fuel I couldn’t siphon out. It got recycled to lawn mower duty.
Using a flathead screwdriver and a hammer, gently drive the ring off in a counterclockwise direction. The ring holds the sending unit in place and usually takes a few taps for removal.
Carefully place the fuel tank on the floor jack for installation. The tank is a fragile box fabricated of sheet metal so handle it and install it with care. Move the tank into the proper position for installation. Gradually raise the jack and make sure the tank doesn’t bottom out against the trunk. Don’t dent the tank. Essentially everything goes back in the order in which it came out. Don’t worry about the space between the gas tank and the trunk floor; it has a good 1/2 inch of clearance.
Everything is ready for hook up. The downpipe for the fuel filler neck comes next and the wiring harness quick-disconnect. I used a rubber grommet to protect the wires and slipped the gas tank filler hose over both pieces. Afterward, two large worm-gear clamps were used to prevent leaks and secure the bond between the filler and the gas tank.
Cinching the two 9/16-inch nuts slowly secures the tank to the car and forms the correct bends for the straps (they begin as straight pieces).
Route the rubber shroud over the filler neck and secure it in place with the four machine screws.
Tank Replacement Sources
The following are a few companies that sell stock replacement fuel tanks.
Contrary to some popular hot rod lore, a stock F-Body gas tank can be converted to fuel the LS engine to supply its fuel injection system. You need to install an aftermarket fuelsending unit in the tank, and this process requires a significant amount of work. If you are up for the task, it is a good way to a save a few bucks along the way.
You need to install a fuel-sending unit that is entirely different from the stock unit. Many in-tank fuel pumps are compatible with the stock F-Body tank and the LS engine series. Aeromotive offers the in-tank 340 Stealth Fuel Pump and Racetronix offers a kit for LS engines that has a drop-in wiring harness and a Walbro GSS340 fuel pump. For my particular build, I selected a kit from Robb McPerformance (RobbMc) that does the trick.
I spent a few extra bucks and had them add an -8AN option that allowed me to run the -8 line to and from the fuel tank. This is a direct drop-in replacement for the factory unit and gives me an option to run a return line via this sending unit or just cap it and not use it. RobbMc told me that it would be best to run an external surge tank with their system to aid in fuel delivery and stop unwanted fuel starvation under lateral forces. They recommend a 1-gallon upright tank between the fuel tank and the fuel filters.
As far as I know, no one makes a tank for this specific purpose, so you might have to make one to fit your custom application. I have found a few surge tanks on eBay going for roughly $250; the route you wish to take is up to you.
You can also install an internal pump and sending unit in the stock gas tank to complete the task of plumbing a fuel system in your F-Body. The system comes from Tanks Inc. and requires a fair amount of fabrication and fitment, but if you are looking for a low-buck way to go, this might be the ticket.
The system uses an internal pump assembly that needs a large hole cut in the fuel tank to allow the pump to rest inside, as the stock hole isn’t big enough. As of this writing, Tanks Inc. has changed their design from this version; so current units may look slightly different.
At the same time, you reuse the stock sending unit opening. You have to remove the collar that’s welded on from the factory to make this work, but it allows you to run a fuel level sending unit without interfering with the new pump. The important factor to remember is the ohm reading from your gauge, which typically is 0 to 90 ohms for a standard GM gauge.
Electric Fuel Pump Installation in Stock Tank
I purchased a stock second-generation fuel tank from Tanks Inc., and I will install an electric fuel pump and related parts in this tank for an LS engine setup. You need to start out with a new tank when installing an electric fuel pump. You risk creating an explosion by drilling into a used tank. (Photo Courtesy Dennis Warhurst)
Use a hole saw to drill a 41 ⁄2-inch hole in the tank to accept the fuel pump unit. Using a sheet-metal hole saw from the local hardware store I made the cut at the most obvious location to get the most fuel to the assembly. Do not drill holes in the fi rewall any larger than necessary. You want to be able to adequately seal the passenger compartment and keep moisture and the elements out. (Photo Courtesy Dennis Warhurst)
This is a perfect spot for a new pump assembly. Use a file or a sander to clean up the edges and take the burrs off. (Photo Courtesy Dennis Warhurst)
The kit includes a fuel pump, mounting hardware, and the correct wiring to complete half of the job. A Walbro 255-lb/hr pump is usually sufficient for most stock LS engines. (Photo Courtesy Dennis Warhurst)
Cut a significant chunk out of the assembly as these are designed to be universal. Take a quality measurement before cutting. Ideal clearance is roughly 1/2 inch from the bottom of the tank when measuring from the top of the tank. You want the fuel pump filter sock to be close to the bottom of the tank, but not so close that it cuts off fuel supply. (Photo Courtesy Dennis Warhurst)
Remove the excess length by using a hacksaw or reciprocating saw. (Photo Courtesy Dennis Warhurst)
A series of holes needs to be drilled to properly match the unit to your fuel tank. Using the unit as a template is the easiest method. Install the support ring that comes in the kit. Some rings snap into place and others bolt. My version bolts into place from the top and bottom. Pop rivets were used to firmly attach the lower ring. (Photo Courtesy Dennis Warhurst)
The stock sending unit hole needs to be covered. You can use a variety of methods to do this such as welding it closed or fabricating a cover with a rubber gasket, but it needs to be watertight to prevent fuel from sloshing out. The top ring needs to be removed carefully. (Photo Courtesy Dennis Warhurst)
I bought a fuel level sending unit from Auto Meter. Although Auto Meter doesn’t make a GM version, Ford makes one that uses an incorrect 240-33-ohm reading. Instead, a VDO version (PN 226008) can be had for $40 and works equally well. (Photo Courtesy Dennis Warhurst)
You have to shorten the level sending unit to match the depth of the tank. Measuring the tank depth gives you an idea of how much you need to remove from the universal sending unit. Using your favorite method of metal removal, you can then reattach the fuel bucket for a customsized unit. In addition, drilling a couple of holes to accept the new sending unit is required (shown). (Photo Courtesy Dennis Warhurst)
A fully installed sending unit complete with cleaned-up welds. Depending on your welding skill you may have to use an aggressive grinding pad. The point of this exercise is to make as clean a connection as possible. (Photo Courtesy Dennis Warhurst)
This is the bottom of the tank. In order to have your gauge read correctly, you need to carefully measure your level sending unit so it accurately functions. (Photo Courtesy Dennis Warhurst)
This is the pre-assembled pump unit with the sump. The return line is neatly secured and not dangling. (Photo Courtesy Dennis Warhurst)
A completed gas tank fully assembled and ready for install and no welding was required. (Photo Courtesy Dennis Warhurst)
The kit from Tanks Inc. comes with a cork gasket to close up any nasty air. So far this tank with this setup has not given me any problems. (Photo Courtesy Dennis Warhurst)
You can also buy complete, readyto-install fuel tanks with the electronic fuel pumps fitted inside them so you don’t have to fabricate the fittings and install the fuel pump in the tank yourself. Aeromotive Stealth Style is a reproduction tank that simply replaces the stock one and neatly fits in the tank straps. This tank fits the 1967–1969 F-Body cars and contains the 340 Stealth Fuel Pump with integral in-tank performance baffling. The in-tank 340 provides enough fuel flow for up to 700 hp EFI and up to 1,000 hp carbureted, but it must be used in conjunction with the correct Aeromotive bypass regulator. You need to install the tank itself, hook up the electrical wires to the wiring harness, route a fuel supply and return line, and the job is complete.
The tank features a stamped steel fuel tank, silver powder coat finish, EFI-style internal baffling, 0- to 90-ohm universal fuel level sending unit, black anodized pump hanger assembly, 340 Stealth Fuel Pump (PN 11140), pre-pump filter sock assembly, and three ORB-06 ports (outlet, return, and vent).
This stainless steel tank functions like a stock tank and is quite possibly the best product on the market for fuel delivery of an LS engine, especially if the car is going to be raced in any capacity.
My tank is a killer product from Rick’s Tanks that is perfect for this application. It’s a stainless steel direct replacement for the factory tank, and it’s compatible with minitubbed cars. The 18-gallon tank is 383 ⁄8 x 207 ⁄8 x 73 ⁄4 inches, and has a 0- to 105-ohm fuel sending unit. This drop-in fuel tank is stamped similar to the OEM tank and the stock fifthgeneration pump electric fuel pump supplies 50 to 60 gallons per hour at 85 to 115 psi.
To install it, you lift it into position, slip the factory tank straps over it, and secure the tank straps. Then you run supply and return lines to your injectors and connect the electrical wires to your 12-volt system. The fuel pump needs to be primed before operation. Although this tank far from cheap, I have to run this type of tank for my application.
The VaporWorx fuel setup has a great design, which uses two pickup points on either side of the fuel tank and one at the pump to pick up every last drop of fuel even in hardcornering situations. These pickup points eliminate the need to run a surge tank and also allows you to really throw the car around without worrying about fuel starvation. This system is an add-on for the stainless Rick’s tank and in my opinion is money well spent.
Fuel Pump Installation in Fuel Tank
The fuel pump for the VaporWorx fuel setup is installed in the Rick’s stainless steel tank. I dropped in the fuel pump, connected the side pickups, and locked it all in place with a lock ring. Then a custom-made harness by Carl Casanova at VaporWorx makes sure all the electrical connections are secure. The opposing fuel port and electrical port tell you that this is the stock pump and not the upgraded version for LS9 or LSA requirements.
Russell’s makes the fuel line adapter, which is essentially two halves squeezed together. It installs and tightens in a jiffy. The part has a small collar on one end that sandwiches the plastic nipple on the fuel pump. Be very careful as these plastic nipples can break easily; I went through two pumps having to learn the hard way. I went with the -8AN (P/N 644003 black), which is the push-on style and requires the standard GM 3/8-inchSAE disconnect.
To complete the install, an F-Body fifth-generation fuel pump, O-ring, and sprocket to tie everything down are needed (G5FM for the fuel pump), all from VaporWorx.
Make sure to connect the two-sided feed lines to the lower inlet tube for the pump. Slip the fuel lines over the nipple and then tighten the pipe strap fittings.
Install your gasket snugly. Simply lay the gasket into the channel, making sure it stays in place. Press it into the channel of the sending unit hole. Also notice the setscrew for the locking ring.
Use a pair of pliers to firmly seat the ring into the grooves and pull tight. You must rotate the ring until it locks into position.
Use a small No. 1 Phillips screwdriver to tighten the setscrew.
I ended up using about ten of these hose clamps throughout the car. These clamps are available in packages of six from Russell (PN 650990). I put these at regularly spaced intervals to keep the cable routed out of the way of potential hazards, such as road debris and heat from the exhaust.
Simply attach the end of the hose making sure you have the correct radius bends.
The weather pack snaps right in place. A weather pack connector is a plastic connector that protects the electrical components from the weather and elements. The wiring harness has a provisional weather pack that is the perfect reciprocal for the pump and harness
On the Rick’s Tanks tank, a provision is made for a 10-mm bolt to be screwed in to hold a fuel line clamp. A standard 10-mm bolt will work. I took quick advantage of that and installed the fuel tank breather tube right next to it. When installed, the breather tube has a small tube running above the tank to allow excess gases to escape.
With the GM wiring harness matched up, I ran a positive and a negative wire to the fuel level gauge. I spliced the wires from the Mast unit and the gauge cluster, and then fastened them to the pump and sending unit. Now I can put the tank back into place.
Carl at VaporWorx has reworked the stock wiring harness and created his own. He removed the unnecessary wires and only kept the important bits such as the fuel level sending unit and the pump wiring. The setup comes with the two halves and some extra clips if you need them. The two halves connect in the middle and allow you to run the wires from the main harness to the gas tank while allowing you to remove it without binding the way the original harness did.
The new wiring harness has been installed and it looks very clean and fits well. I’ll feed the other half through a grommet in the trunk where the fuel level wire would go and make the weather pack connection through the license plate access hole.
This tank-and-pump combination is an entire assembly in one unit. It may be a bit pricey for a fuel pump but you need to consider the value of this system because it saves time and is convenient. The returnless system is not vacuum regulated so that means you only have to plumb one fuel line. It has an internal regulator attached to it so that part of the equation is taken care of. It also includes its own filter built right into the fuel pickup of the unit. In addition, pump depth, the choice of correct pump, welding, and pressure testing of the tank (that’s all the components) are set so you don’t have do a lot of trial and error to figure out the setup. It’s a foolproof system.
This pump is not correctly calibrated for the LS engine. The internal regulator of the pump comes with the fifth-gen pump that’s not at the correct setting and has to be replaced with a fourth-generation fuel pressure regulator and adapter. Replacing the regulator with a VaporWorx adapter is fairly straightforward.
Adapting the wiring is the most complicated part of the setup. The fifth-generation pump has a fourwire weather connector that needs its own special male connector. You can always forgo the weather connector to cut and splice the wires. That typically means using a wire cutter, stripping the ends (using your favorite butt-style connector), and a strip of marine-grade shrink tubing. Some aftermarket companies have worked out solutions. VaporWorx has reworked the wiring to fit the older style (and simpler) wiring systems. They have specialty wiring harnesses for first and second-generation F-Body applications.
For my particular build, when I installed an LS3, I discovered that the LS3 pump for the fifth-generation F-Body and the CTS-V are different.
In fact, the CTS-V delivers a much greater fuel volume because it has to feed a supercharged beast of an LS engine.
The easiest way to tell what pump you have is to look at the upper feed line. If it is parallel to the weather pack connector (like mine), you have an LS3 pump. If it is at a 45-degree angle, you have a CTS-V pump. The CTS-V is basically two 190 lph pumps in one unit with the similar proportions as the fifth-generation pump. If you have a high-horsepower setup, the CTS-V system might be your ticket. But it must be said that running this pump requires a lot more effort and is not the same setup as the fifth-generation pump. The CTS-V pump has two feed lines and it requires a different wiring harness than the fifth-gen version.
VaporWorx stocks the correct fuel pump harness for custom applications if you don’t want to wrestle with making one yourself. It is possible to buy a stock wiring harness and modify it to fit, but from my experience, the VaporWorx is the best on the market at the current time.
AN Line Fabrication
You typically need to install a high-pressure line at some point in the build. A high-performance or protouring F-Body car must flow a lot of fluid through its systems, whether it’s an oil cooler line, transmission cooler lines, power steering, or fuel. They all need to be correct to work best.
Most fittings have two parts with matching threads: a sleeve and an insert. These fittings are extremely durable and can be reused many times.
Custom AN Hose Fabrication
When first making a braided line, start with the correct-style end that you want to use and hold it in with a tabletop vise.
Use a dab of Earl’s assembly lube to make the braided line installation easier.
Make a clean cut on the hose. Use a cutoff wheel, hacksaw, or a sharp stonecutter and a mallet. Be sure the cuts are clean. Once it’s cut to the desired length, you then slip the other half of the fi tting onto the hose for mating.
Push the hose onto the male end while screwing the female end into the fitting. This may take some force, so don’t be afraid to really push.
Finally, use the correct-size AN wrench to tighten the nut until it seats almost all the way. You have made one half of your new custom-made braided hose.
The procedure begins by taping the length of hose you need so when you cut it, it doesn’t fray. Cutting the hose can be done with a hacksaw or cutoff wheel. Earl’s recommends using a sharp stone chisel that creates a perfectly clean cut each time without tape.
Next, place the collar over the line using a vise to hold the collar in place. Sometimes a bit of force is needed to get it in place. Now you can place the threaded hose end in the vise and start threading the collar and hose into place. Continue to work it into place until the threads grab and turn by hand until you cannot turn it anymore.
At this point use a wrench to continue threading the hose onto the end. A little piece of mind goes a long way, especially at 7,000 rpm! This may take a few tries to get it right, but once you get the hang of it, making your own hose ends is the only way to go.
If you have a cable-driven throttle body, you can most likely skip this section and use your existing setup with a modified cable. Modifying your existing cable is simply a matter of determining the length you need to articulate the throttle body. If you’ve been running a carburetor to this point, you may have to replace your cable with a longer one and make the necessary length adjustment. Keep in mind that you have to be able to run it wide open, so double-check that you have full articulation from your pedal closed to open.
If you don’t have a cable-driven system, you have a drive-by-wire (DBW) system. This means you need to mount the gas pedal. In all likelihood, this is the only bit of fabrication you will have to do. I have only seen two styles of DBW pedals: those that mount with bolts going through the pedal sideways and those with two bolts going through a bracket (such as the one I have in my car).
You need to have the correct pedal with the correct wiring harness for it to work properly. If not, you have to reflash the computer with a different gas pedal and this is extra hassle and expense. In some instances you can get away with it, but just to be on the safe side, you should have the gas pedal that came with the engine whenever possible.
Either way, you have to fabricate a way of mounting your gas pedal. In this case I chose to make a box that located the pedal in a desirable location. It is best to have the pedal closer to the floor than the brake pedal by about 2 to 3 inches and offset to the side an equal distance.
The floorboard/firewall of the F-Body has a lot of complex shapes and requires a bit of finesse to get the pedal mounted properly. Mine had to be cocked about 20 to 30 degrees to match the look and position I desired. It is important to reinforce whatever you build as you do not want this thing coming loose during a spirited driving session.
Written by Eric McClellan and Posted with Permission of CarTechBooks