It all started because I was having a fuel problem. After driving the Valiant for any extended period of time, it would act like it was running out of fuel. When I was finally able to get the time to look at it, I found that the stock mechanical fuel pump was heat sinking (absorbing the heat from the engine), and vaporlocking.
There are a couple of different ways to remedy this situation. One would be to plumb a return line from the pump to the fuel tank, giving the pump a constant flow of circulated fuel. Since the fuel would be in continuous cycles from the tank to the pump and back to the tank, it would effectively help keep the fuel pump cooler. Another idea is to remove the pump from the engine. To do this requires installing an electric pump in the system.
An electric pump is designed to be more efficient if it is installed in a location as close to the tank as possible. The reason for this is to "push" the fuel to the carburetor, as opposed to being mounted near the engine and "pulling" the fuel from the tank. Knowing that the Valiant will be receiving a different engine in the future with a larger appetite for fuel, we decided to do more than simply install a pump near the tank and call it quits.
The fuel tank already in the...
The fuel tank already in the Valiant had sprung a leak, so it was definitely time to change it. Our new one from Year One fit the bill nicely. A new tank is also good insurance that no junk will contaminate your fuel system.
Fitting the universal rear-sump...
Fitting the universal rear-sump kit to any fuel tank will require welding and modifications. The Valiant has a fuel-tank strap that runs from framerail to framerail. The strap actually runs right where the sump gets welded to the tank. We would have to modify our sump to end at the strap.
We cut the sides of the sump...
We cut the sides of the sump so the bottom could be folded over and make the back of the sump where the tank strap crosses. We then welded the folded metal back to the sides. This wall at the back of the sump acts like a dam and helps keep the fuel in the sump during deceleration.
The sump kit comes with this...
The sump kit comes with this diagram to show you where to drill the 2 1/2-inch holes in the tank. If you cut the tank to the size of the sump, you take some of the rigidity of the tank away, and now there is no baffling for the sump. Just take a center punch and mark the holes, and then drill with a hole saw. We didn't need the hole closest to the front since we shortened our sump.
After the holes are drilled,...
After the holes are drilled, it's time to weld the sump to the tank. Begin by spot welding at the corners and make sure the sump placement is where it should be before you do any more welding. When you weld the sump to the tank, take your time and weld at different locations to avoid warping the tank. When you have the entire sump finally welded, you can grind the welds a little to clean them up and make the job look nicer.
After you have tested the...
After you have tested the welds to make sure there are no leaks, you can paint the tank. As added insurance, a thin coat of epoxy over the welds can be cheap insurance. Now, the sending unit will need to be removed from the old tank and put in the new one. A cap plug will need to be installed over the factory feed location.
There are two outlets in our...
There are two outlets in our sump, one gets plugged and the other will feed the pump.
It was decided that a Holley...
It was decided that a Holley "Blue" fuel pump would suffice our needs.
We mounted our pump on the...
We mounted our pump on the rear framerail, tucked up out of sight.
The fuel tank in the Valiant has been in the car since it was built. As such, it's hard to say what kind of debris and gunk has attached itself to the metal inside. Sure, there are ways to clean a fuel tank, but when we noticed a leak, we knew the time for a new one was upon us. The problem with simply replacing the old tank with a new one is the original feed line out of the tank is only 5/16 inch. Feeding any kind of high-horsepower engine with that size line is asking for trouble. Another downfall is the fuel is sucked from the front of the tank. Fuel starvation during hard acceleration is an issue we wanted to avoid. To best solve the issue presented by a stock fuel system, we ordered a new fuel tank from Year One and a universal fuel-tank sump kit from Competition Engineering. The task of installing a rear fuel sump to any fuel tank requires welding and modification. If you are not comfortable with welding to your fuel tank, seek professional help. For those of you that do feel comfortable, please make sure to take the appropriate measures so there is no explosion while welding if you are using the old tank.
Having a modified fuel tank is only half of the equation. You need to get the fuel from the tank to the engine. Several companies make aftermarket fuel pumps, and deciding which one is right for your application requires you to plan what the demands on your fuel system are. We were not in need of a full-boogie, Pro-Stock-style fuel system, so we ordered a Holley "Blue" fuel pump. The Holley pump comes with the required fuel regulator, and will sufficiently feed a strong running street mill. The Blue pump will free-flow 110 gallons of fuel per hour at 14 psi. Since the 14-psi rating will overpower the needle and seat assembly in the carburetor, Holley also supplies the needed fuel regulator with the pump. We could have simply bent up some steel line and rubber hose for the connections, but we wanted the finished system to look like we knew what we were doing. Earl's, a division of Holley, has just about every fitting and hose you would need to install a complete fuel system in your Mopar, and we decided to give them a try. Before you order parts for your fuel system, it is a smart idea to draw a picture of the system you plan to build and write down the part number of every fitting you will need. Simply trying to play it by ear and hope for the best will result in a lot of phone calls to get more fittings and down time for your car. Now that we gave you our rendition of why and who, let's get to the meat and potatoes of doing it.
To cut the hose, you first...
To cut the hose, you first need to measure where it will be cut and then wrap it with masking tape. This will keep the ends from fraying as you cut it with a fine-toothed hacksaw.
Next, slide the collar over...
Next, slide the collar over the hose-after you remove the tape. A little WD-40 can help.
Now, simply screw the other...
Now, simply screw the other half of the fitting into the collar. You want to leave a distance of about one thread thickness between the collar and the insert when tight.
We installed a breaker and...
We installed a breaker and cut-off switch in the trunk of the car. The switch and breaker are mounted inside the battery box.
The fuel regulator was mounted...
The fuel regulator was mounted to the engine underneath the alternator. The inlet comes up from the bottom, and you can see the aluminum hard line previously installed ready to be connected.
Earl's has this handy fitting...
Earl's has this handy fitting that connects a hard line to their flexible-braided line. Simply slide the collar over the hard line, put the rubber sleeve on, and tighten to the soft line fitting.
Next, run your fuel line from...
Next, run your fuel line from the regulator to the carb. We ordered an aluminum dual-feed line with an outlet out the back. The second outlet will feed the fuel solenoid for the nitrous. Make sure when you route your fuel line up the front of the engine to keep it away from moving parts.]
The outlet at the back of...
The outlet at the back of the carb feed-line is plumbed with -4 line to the fuel solenoid.