Im confused on this fuel gauge problem.

[MelectroK]

I have been having intermittent fuel gauge issues. Maybe someone can help.

The problem is when I start my car the gauge will be reading E and the light will be on even though I have gas.

I dont have this problem all the time. Here are the situations.

1) I replace my fuel pump and for the next fuel days there is no gas gauge reading.

2) I stop at a store to buy a dvd, come back out start car and no gas gauge reading.

3) Start my car after a full days work and no gas gauge reading.

The gauge always starts working again a day or two later. Two times it started working as I was driving. The third time was when I started the car back up the next day it was working.

I dont feel that the problem is a loose wire or connector because, EVERY time I have had this problem it works fine when I turn the car off and then isnt working when I start it back up. If it where a loose wire or connector I would think that a bump or jolt would cause the problem. But when the car is turned off there isnt any bumps or jolts.

The problem always occurs between 1/2 tank and 1/4 when it stops working.

Do any of you feel that there is a problem in the slosh module area or wireing? Or do you still suspect loose wire even after the opinion I just gave?

Thanks.

P.S. I am trying to contact the previous owner of the car to see if he ever had that problem. I am doing this because I had to replace the fuel pump 2 days after buying the car and never really used the old one. I did at that point replace the whole sending unit. If he has never had the problem, I may suspect that it is something I caused which would mean sending unit or connectors at the tank.

 

[rangerj]

A commmon problem with the fuel gauge is a poor ground connection, or a poor or corroded connection back at the tank. If you think it is the gauge then I'll post the tests for the gauge. Do you have analog or digital gauges? rangerj

 

[MelectroK]

Doesnt the fuel pump use the same ground as the sending unit. If the sending unit loosed ground to make my gauge not work, why does my fuel pump stay on?

 

[rangerj]

I do not know about your car but on my 90- the four wires to the fuel pump/sending unit are 1) sender ground, 2)magnetic gauge, 3) pump positive, and 4) pump ground.

The pump and the gauge do not operate off of a common ground. The gauge operates by the variation in resistance between the power and ground.
rangerj

 

[MelectroK]

okay then if that is the case, is there any reason i cant tie the two grounds together just before they enter tank, if that may be the problem? Also, do you know where those wires are factory grounded at?

 

[rangerj]

There is a plug that plugs into the sending unit/fuel pump that all four wires are connected to. I'm not sure that connecting the two ground wire together will solve your problem. The gauge gets variation in resistance from the sending unit circuit(as the float rises or lowers in the tank the resistance varies). If you add the pump ground into the circuit I do not know what affect that might have on the gauge. Try jumping the ground to the body, or connecting the two grounds and see what the gauge does. rangerj

 

[MelectroK]

I only ment it for testing. I just wanted to konw if touching them would send a mushroom cloud from my dash

 

[rangerj]

Providing a "ground" should not cause a problem (no mushroom clouds). Apply a jumper wire too a good ground and see if the gauge reacts. rangerj

 

[Bizzy]

The problem always occurs between 1/2 tank and 1/4 when it stops working.

Does it happen at all when the tank is above half full? If it doesn't then I'd think that maybe there is some issue with the float signal to sending unit perhaps. I'm no fuel pump expert here but if it doesn't happen when the float is higher in the tank....see where I'm going with this? Could be the sending unit, I really don't know.

 

[MelectroK]

It has only happened 3 times. Every time was about the same amount of fuel in the tank so far. I was suspicious of that as well. That is why I am still trying to contact the previous owner and see if he ever had a problem like that. Otherwise a grounding issue is all i can think of i guess.

Do you know where the factory wires are grounded at.

 

[rangerj]

The fuel gauge sending unit is grounded to the chassie (body). Jump the ground wire to the body and this will tell you if it is a "ground" problem.

You could pull the sending unit(pump) and test it through its range of motion to see if it operates the gauge in its full range E to Full. If the sending unit
has a "flat spot", it will show up in this test, that is the gauge will not act properly when you get to the bad spot. rangerj

 

[Bizzy]

try taking a hose out and spraying water all around your gas tank. My sneder only works when it is raining, I know there is a ground problem in the connector on the fuel pump harness. I'm thinking that there is no dielectic grease there.