Runs fine on full tank, but not on 1/8 tank

[the_communists]

Experienced run-out-of-gas symptons at about 1/8 tank (car sputters, looses power). I limped it to a gas station and filled - I noted from the amount of gas I put in, the tank still had 2 gallons left when it had the problems.

I have run several (3) bottles of isopropyl alcohol and the problem has not gotten any better after 2 tanks. In fact, it may have gotten slightly worse in the past week (just below 1/4 tank now it run out).

I've read in some cars this may be result of failure of a fuel relay (booster) near the main tank, so when the tank is low, it doesn't get fuel to the main pump. Not sure the 330 has this configuration. Anyone know?

The other possibility is clogged filter.

Appreciate anyone who might have insight, and someone could tell me where the filter and relays are located if indeed these are suspect.

[malcolm brumley]

I have expirenced this in another car which might be your problem. It was the strainer on the fuel pump in the gas tank clogged with trash. It has to be removed and cleaned or replaced.

[Stephen 325TDS]

When I had similar symptoms in my car, it was the fuel pump itself ( the one under the rear seat, in the tank, as mentioned by Malcolm). 'completely cured by new pump.

Stephen

[JSvenson]

You think the fuel gauge is broken?

[the_communists]

Originally Posted by JSvenson

You think the fuel gauge is broken?

If it is, my fuel tank spontaneously shrank in size. When I filled up with fuel, it's not the full 16 gallons it normally would hold at empty. It's more like 14.

I think I may know the problem - the car has lost alot of power during heavy acceleration. I think something is constricting or limiting the fuel, and when the tank is low, it limits it even during normal accelerating conditions. Either fuel filter or pump.

[erussell99]

Ahh so glad to find someone having the same problem. I have a 1993 325i that was doing the same thing. Now it has the same symptoms on a full tank of gas. Really making me nuts. I have tested almost every component in the Fuel injection system with no issues. I have a feeling it is the pump however when I put the gas all the way to the floar it teh engine seems to catch. This makes me think it is something else. I will le you know what I find.

Thanks Ed

[the_communists]

The fuel pump. I went below the back seat, removed the cover over the tank area. Then, saw the wires going into the tank with an unusual fitting above the tanks. Now, this is still a 2001 330i in excellent condition, bluebook value $25K. I couldn't afford messing it up. So, I abandoned the repair and took it in to the shop. The fuel pump needed to be replaced. There was a buzzing pump noise that could be heard if all was quiet. Much more power now under accelerating conditions, and it goes all the way to near empty tank.