Fuel Pump Replacement - Strange Fuel Levels

[BIGRED]

I have started to work on replacing the fuel pump and the fuel pressure regulator.

Before heading into the tank, I wanted to be prepared to clean out any gunk in it. So the first step is to drain the tank. I read Bentley's and as usual it left me in a lurch. it gets close but is not exact, in this case about the various relays to jump to run the FP without cranking the engine. The diagrams and locations are WRONG.

That being the case, I spliced into the return fuel line at the point of the return line entrance to the tank, so that I could route the return fuel into a gas can.

Started up the car and went through the painfully long process of pumping the fuel into a can and pouring it into another car.

I noticed that at the point just before the reserve light came on, the stream of fuel started to have small bubbles as though it was sucking air. I checked and the car was almost perfectly level.

When the reserve light came on, the fuel stream went from flowing (with the bubbles) to a trickle to no flow to a slight flow and so on. I was watching the stream for a clear sign I had a pump problem. Pump seemed to be working fine up to this point.

I assume that the tank is near bone dry and that the sending unit isn't working as it should or there is a air leak in the fuel components in the tank (hose or plastic parts) above the current fuel level so that it is sucking air.

Assuming the tank is dry, when I get into the tank and remove the guts, I should be able to hook up the sending unit and try it out of the tank and see if there is a way to adjust it to make it more accurate.

[pgrindstaff]

I had to replace my fuel pump last summer due to its complete failure. Unlike you, I did not drain the tank, but had probably half a tank to dive in to. As for the sending unit, I'm not sure if there is really anything you can adjust, its just a plastic tube i guess which gas runs through, a seemingly simple part. I'm not saying it can't be adjusted, I just didn't see any way to do anything to it.

-Patrick

[BIGRED]

It seems that the motor portion of the pump is isolated from a hard plastic frame by a rubber component designed to isolate it. In my case the pump motor was permanently tilted within the rubber part, which was somewhat deformed. It is possible that there is pressure against the pump (and therefore tweaking the rubber) created by the fuel hoses between the pump and the sending unit....which is the cause of the problem in the first place. Being the pickup is tilted and not laying 100% flat, caused an earlier suction of air even though there was more than an inch of fuel.

Don

[winfred]

if it wasn't straight someone probably didn't snap it back in right the last time it was out of the tank, the pump and the plastic cage snaps into the plastic piece on the floor of the tank, you don't need to drain the tank to service the pump unless you just don't want to reach into the gas to squeeze the clips to release the pump/cage from the fixture on the bottom of the tank, the other way to drain the tank is to just unscrew the plug and let it piss into a _______

[BIGRED]

if it wasn't straight someone probably didn't snap it back in right the last time it was out of the tank, the pump and the plastic cage snaps into the plastic piece on the floor of the tank, you don't need to drain the tank to service the pump unless you just don't want to reach into the gas to squeeze the clips to release the pump/cage from the fixture on the bottom of the tank, the other way to drain the tank is to just unscrew the plug and let it piss into a _______

The plastic cage is isolated from the pump with rubber parts. The rubber was tweaked and would not allow the pump (when snapped in properly) to sit at a true 90 degrees from the tank bottom.

I drained the tank because I wanted to be sure.... there was no crud in it and if there was, to clean it out.

Not sure what part can get unscrewed. Is there a plug in the tank?

Don

[winfred]

yep, 5mm allen plug on the right side

Not sure what part can get unscrewed. Is there a plug in the tank?

Don

[BIGRED]

Good to know.. thanks