Auxiliary tank problem?

[GBurton]

I have an auxiliary fuel tank mounted in the bed of my truck. The fuel line exits through the top of the tank. From there it goes down to the transfer valve that selects either the main or auxiliary tank. When using the auxiliary tank everything works great until the fuel level in the auxiliary tank gets down to about 3 or 4 inches of fuel, as measured with a dip stick not just the fuel gauge. The truck runs fine with that amount of fuel in the tank but if I stop and let the truck sit over night, the starter runs much longer than normal before the engine will start. If I remember to switch to the main tank before I try to start the truck it seems to start all most normally. It does not matter how much fuel is in the main tanks, As long as it isn

[letsgo]

Would there be a "check valve" on the fuel line inside the tank that is stuck open allowing the drain back??????????

good luck

[Paintdude]

I would try tightening all the clamps..Sounds like air is getting in someplace..

What does it do if the truck would set for a few days? I am betting you would have to prime it..

Do you park the truck on a incline? Is the tank pickup metal or rubber hose in the tank?

Good luck, just some ideas..

[Idle_Chatter]

GBurton, I think the problem is a combination of the tank design and that 3 or 4 inches is not enough fuel. I have the American Tank 43 gallon tank. The American tanks have a "box" or square baffle plate about 6 inches tall in the corner where the fuel pickup is located. The fuel return line also dumps down into this baffled area. The fuel pickup in my tank was not dead on the bottom of the tank, maybe 1/2 to 3/4" off the bottom, so I figure that I've got to have at least 2 or 3 inches of fuel to keep it covered. When you start up, the pump sucks down that 3 or 4 inches in the baffle and may be sucking air up the pickup before the tank can flow fuel back into the baffle or the return line starts to dump back into the baffle. I've pretty much gotten into the routine of using only 32 gallons of my 43 gallon aux tank. I swap tanks at the "low fuel" light and then put 32 gallons in. This leaves me about 4 to 6" of unused fuel in the bottom of the aux tank. I'd check for air leaks on your hoses and try leaving another inch or two of level in your tank.

[dmaxstu]

George, I too have an auxtank and when I installed it I was surprised that the pick-up tube was made up of 2 pieces joined together wth a compression fitting inside the tank, at the time I thought that setup could cause some problems in the future. The problem I envisioned is about what is happening to you, a partial loss of the prime if that connection should become loose, just a thought. Stu

[ 12-18-2002: Message edited by: dmaxstu ]</p>

[TBC]

I have a 41 gal RDS (Northern Eqpt)tank and have several times ran it down to the point where I put 38 gal in it and only once did it cause a problem and that was in the mountains and I was not thinking that the level was that low because the gage was indicating slightly more than was actually there. I try to switch before it gets down to the point it would suck air. Level ground gage is ok but in hills and mountains I switch at just under a 1/4 tank indicated.

I don't know what type pickup is in mine but it seems to be metal tube from looking at the drawings. I think if the tank is not venting properly the tank will create a vaccum and would suck the fuel in the feed tube back into the tank creating an air pocket. Check the cap or replace it.

Tom