When the gas tank is less than half full, I get occasional hesitation hard enough to put my teeth in the steering wheel. When I disengage the clutch, the car immediately stalls, but will start right back up upon cranking.

I've already had the PRE-PUMP replaced. I have heard that there is a fuel line attached to the prepump that has a tendency to crack over time. Is this true? I'm convinced that this is a fuel issue since the car will not hesitate when the tank is above half-full. The car feels as if it's starved for gas.

My mechanic already checked the main pump and it showed no pressure problems. Are there fuel lines I should check? Any ideas would be very helpful.

LMT

The key to this problem is, "When the gas tank is less than half full,...", and only secondarily, "...occasional hesitation hard enough to put my teeth in the steering wheel...."

The other suggestions, about fuses, electrical connections, etc., are only valid if the problem occurred at any level of the fuel tank. Only the hose problem -- a split or leaking hose that's between the transfer pump and the fuel line -- is predicated on the fuel level being at or below the midway point!

And I doubt that the intermittant failure of the transfer pump because of electrical problems would cause such drastic losses of power, since it's only an aid to the flow; on the other hand, air (actually fuel vapor) getting into the fuel line because of the leaking hose would definitely cause such abrupt losses of power!

It's a shame, though, that your mechanic was too lazy or incompetent to change that little hose when he changed the transfer pump. Now you have pay all the labor charges all over again to virtually repeat the entire job (that hose would have just cost 'loose change' if it was added to the original job). But on second thought, maybe your mechanic knew just what he was doing, after all [maybe he's got a kid about to start college?]!

I'd go to another mechanic.

If the tank pump has been replaced, a cracked hose could not have been missed. I always go back to the most recent work looking for an error, but in this case it might be as simple as corrosion on fuse number four. This fuse protects the wiring to the tank pump and the oxygen sensor's heating element.

Even though the pre pump has been replaced, it still may not be doing it's job.

It could be bad/defective, have wiring problems and not getting any juice, or a cracked/split rubber in tank hose. One would think that if the pump was recently replaced, then the hose should have been replaced also??

Try listening for a whine with the fuel filler cap off ,to confirm that it is operating.

Even better would be checking for volts and current draw with a DVOM.

Bentley lists correct current draw at 1-2 amps for 83- early 86 pumps, and 3-4 amps for late 86-93.

If it is operating correctly, and still no fuel,then you would have to pull it and take a look.
--
Gary Gilliam Sumerduck VA, '94 940 Regina, '86 240GL

One cheap way to check that hose in the gas tank is to buy the special tool on this site for opening the fuel sender unit a top the tank. Its 25 bucks and will allow for you to open it right up through the trunk. If you have ever got a fountain drink and cracked the straw it only works where the drink is covering that cracked spot. Once you drink lower than the crack you get just a little bit. Just a guess and cheap suggestion.