Fuel Tank Problem

[FE135]

My buggy has fuel injection and as I burn down the fuel to about 3 quarters full, The fuel pressure will intermittently go to zero for a second. I’m thinking the problem is my fuel tank since it does not have a sump and during duneing the fuel may slosh away from the pickup which is in the corner. Short of getting a newer tank with sump, has anyone tried foam blocks in the tank and would it help? Are there any other tricks that might work? I’m fairly certain the problem is not the pump.

I will get a new tank if there is no other option.

[SAND~~SNAKE]

I would have to say the pickup is at or near the bottom of the tank and baffles really would not help..Are you sure its not the pump and possibly a heat related problem? After running awhile it does heat up..you can test amperage and pressure before and during when the problem occurs. I only say that cause at 3 quarters full it does not sound logical to me

[Mustache Motorsports]

I would have to say the pickup is at or near the bottom of the tank and baffles really would not help..Are you sure its not the pump and possibly a heat related problem? After running awhile it does heat up..you can test amperage and pressure before and during when the problem occurs. I only say that cause at 3 quarters full it does not sound logical to me

Does the pump suck out of the top or bottom? A lot of the pumps for fuel injection do not like to suck out of the top and need to have some head pressure to work. If that be the case you might need an in tank pump.

[FE135]

I would have to say the pickup is at or near the bottom of the tank and baffles really would not help..Are you sure its not the pump and possibly a heat related problem? After running awhile it does heat up..you can test amperage and pressure before and during when the problem occurs. I only say that cause at 3 quarters full it does not sound logical to me

Perhaps if you saw the tank you might understand. Long but narrow and the pickup is in the corner. If you tilted it at 3/4 full, it would/could leave the pickup point above the fuel level. I am thinking of jacking up the side of the buggy to test the theory.

I am also not 100% convinced the pump is good, it will cost me about $300 to be convinced. That's a new one.

[FE135]

Does the pump suck out of the top or bottom? A lot of the pumps for fuel injection do not like to suck out of the top and need to have some head pressure to work. If that be the case you might need an in tank pump.

It is an external pump that pulls from the lower corner of the tank.

[FE135]

This is from an Aeromotive Tech notice:

The drawbacks to stock fuel tank retention are more numerous but less obvious. The stock pick-up/pump assembly is restrictive, requiring complete replacement with a fabricated assembly. When using a stock tank with fabricated pickup, unless the fuel level in the tank is ¾ full or higher, the internal well, which the stock pump draws from, is far too small and poorly supplied with fuel from the rest of the tank. Faced with the demand of a large pump, drawing through a fabricated pickup, it has no chance of refilling fast enough to support WOT full engine load. Under low demand, cruise type conditions, the large volume of fuel delivered to the rails is unused and returned. The same fuel, picking up heat from the pump and the rails, is constantly recycled to and from this well, rapidly increasing fuel temperature. Common problems associated with stock fuel tanks and fabricated pickups are pump cavitation, vapor lock, varying fuel pressure, exaggerated pump wear and lean conditions during both low and high loads. Note: Unlike a carbureted engine, any loss of fuel supply at the in-tank- pickup will immediately result in a loss of fuel volume and pressure at the EFI injector resulting in lean conditions and engine damage.

The key phrase: unless the fuel level in the tank is ¾ full or higher

I think this is my problem. Now I need to find a tank with sump that will fit in the restrictive space I have.

Does anyone know of a manufacturer of fuel tanks that have a sump, are tall and narrow as opposed to the standard flat square type?

[Randog]

Sounds like lack-of sump is the problem to me.

I have a small sump on mine, and it starts starving at 1/4 tank in hard turns. ( kinda like a reserve ).

Imagine where the fuel goes when you are having a WOT situation and hookin' thee effff through a turn while cambered on a dune ....

Is there any room to add a sump to your current tank?

I'm not a fan of putting the pickup on the end of the tank, but a sump large enough should get you through the situation above.

I'd try that route before buying a new pump.

Maybe a custom fab tank is your answer though?? :ahhhhh:

R-

[FE135]

I agree and have been searching online for a tank with sump. This one might work, the measurements might be close but I won't know till I get out the tape measure.

http://www.summitracing.com/parts/RCI-2150AS/

As a bonus, I would have a fuel guage, no more dipstick. Working late tonight so I'll look tommorrow.

[nightime]

My leaf blower has a pick up hose (in the tank) that falls to the lowest point in the tank when flipped upside down or side to side...It will run upside down or what ever corner I take at 100 mph.

[Noozeyeguy]

Two thoughts... one, is the tank (or cap) vented? If not, the vacuum created in the tank by fuel burn could (theoretically) starve the pump momentarily... or at the least cause cavitation (pumping air and liquid).

Two, if the condition always occurs when the pickup side is (or recently has been) elevated, then you may have your answer. My buggy has a very cramped engine compartment, I'm using a 8"x32" spun-aluminum tank in mine without a sump. But, I'm feeding the pump with -8 AN fuel line which draws from the bottom center of the tank... So far no problems (other than chitty range ).

[FE135]

Since I can't find a fuel tank that would fit the sandrail, I removed my fuel tank and took it to my local welding shop. He is a big off road rock crawler guy. Took one look at the tank and said "thats all wrong". He is going to weld in a proper sump in the correct location. He has never failed me before. I'm pretty confident it will solve my problem. I might get a new fuel pump just to be sure. At worst, I'll have a spare with me at the dunes. I'll take a picture of the finished tank when I get it back. Hopefully, save someone else the headache.

[FE135]

Here is the new sump. You can also see were the original was.

These pics are from my phone.

Here is the whole tank. Long and skinny. Holds about 16 gallons. You will notice the new sump isn't centered. That was by design, had to clear a center rail in the frame. No way around it, no room, tight fit.

This pic shows the problem, tank is at 20 degrees. The stick is 0 degrees to show a fuel level. Doesn't take much to uncover the corner sump and flame out the engine.

This is with the new sump. Much better. Not perfect but usable. The larger capacity of the sump itself will also help keep fuel to the pump. As you can see, I should be able to get down to 1/3rd or 1/4 tank before I might have a problem.

I guess I'll know for sure next time out. I did get a new pump too. Haven't installed it but at least I have a spare.