Fuel Reservoir How To

[Parts Abuser]

Not sure how to do this other than as an attachment, so... Attached is a PDF drawing for illustration.

I've seen a few posts on here about fuel reservoir design. I've used this basic design for over 15 years with great success; from road racing to wheeling. Most of my systems have been used with forced induction, and all on fuel injected applications.

The low pressure pump I currently use on my wheeler is an AC Delco pump from Summit (PN EP12S). This is an inline electric pump designed for a carburetted engine. It has 3/8" hose barbs on both the inlet and the outlet.

The high pressure pump I use is an MSD inline unit. PN 2225 from Summit.

The low pressure side of the system should, from what I've heard, return fuel back to the bottom of the main tank. Apparently, the returning fuel raining down on the fuel in the main tank can generate static electricity, which in turn can go BOOM! I don't know how true this is, and I've never had a problem with my systems, all of which have returned the fuel at the top of the tank. It would be wise to research this if you're going to try to emulate my system.

The high pressure side of things is simple: My current reservoir is about 4” dia. X 10” tall. It is the size it is because I have the room, but I have (successfully) run smaller. How small? The smallest was about 4” square. It worked great. Anybody who's been wheeling (not the kind you do in a mall wheeler; the kind you do with both axles locked) knows that fuel control will stop you in your tracks. Getting stopped in your tracks in the middle of the Rubicon is UNACCEPTABLE!

So, the typical fuel injected road-carving muscle car needs a constant supply of fuel to feed the main pump. This fuel needs to be comprised of 100% fuel (no air). The smallest reservoir I'd run is about two and a half inches in diameter by about six inches tall. The bigger the diameter, the taller it should be. The idea is that when the fuel sloshes side to side, it won't uncover the fuel outlet to the main pump.

The feed and return for the low pressure pump, like the return from the engine, can go into either the top or the side of the reservoir, BUT they need to be as high up on the unit as possible. The outlet to the main pump can, as the drawing shows, be out the bottom or out the side, BUT it needs to be as low as possible.

There have been suggestions that the low pressure pump will fail prematurely due to (enter your favorite reason here). This has not been my experience, though I do carry spare low and high pressure pumps. Again, picture pushing a 3 ton pig up a rock slab when all four tires are trying to climb at once. Not happening. Spares, spares, and more spares.

Final note: GROUND THE FUEL TANKS. Both the main tank and the reservoir need to be well grounded. Don't take my word for this; take a look at any car/truck/boat/airplane/tank/whatever from any reputable manufacturer. The tank is always grounded. ESPECIALLY IF IT IS PLASTIC!!!

Feel free to add your thoughts/experiences.

Cheers,
Vince

[camcojb]

yep, a surge tank. Works fantastic on a road course.

Jody

[vannatta20]

I bought a carter carb pump for my system and did not run a return for my surge tank. I figured since this pump was designed to use with a carb with no pressure reg or return I should be fine. Do I really need a return?

[camcojb]

I bought a carter carb pump for my system and did not run a return for my surge tank. I figured since this pump was designed to use with a carb with no pressure reg or return I should be fine. Do I really need a return?

if your engine is EFI and returning to the surge tank you must have a return line from the surge to the main tank. If not, then the returning fuel from the engine has no where to go which will wreak havoc with your fuel pressure.

[Parts Abuser]

This is something that needs testing to prove/disprove. I'd be interested to hear how this works for you. Does the pressure from the low pressure pump act to raise the high side pressure by restricting, by a small amount, the return line from the regulator to the reservoir?
I've always run a return but then, my reservoirs have always been mounted at the rear of the vehicle.
Let us know how this works, if you decide to go this route.
Vince

[camcojb]

This is something that needs testing to prove/disprove. I'd be interested to hear how this works for you. Does the pressure from the low pressure pump act to raise the high side pressure by restricting, by a small amount, the return line from the regulator to the reservoir?
I've always run a return but then, my reservoirs have always been mounted at the rear of the vehicle.
Let us know how this works, if you decide to go this route.
Vince

I would not run a bypass line into a pressurized (6-7 psi) tank. I agree, you need to test to prove/disprove, but you really don't want to restrict the return line for any reason. I would add an overflow/return line from the top of the surge tank back to the main tank.

Jody

[vannatta20]

The way my system works is like this, Main tank has the carb pump the pulls it into the 1 gallon surge tank. The surge tank has a GM Tahoe fuel pump bucket assembly with an upgraded walbro. From there I used the gm quick disconnect fittings and send the main feed to the corvette reg. The reg then returns the fuel to the main tank. It works great so far but have only but like 100 miles on it.