Fuel Gauge

[NickMav]

I was wondering if any of you had an idea on what this could be. I havent tested anything yet but F is a full tank of gas in my car while 1/2 would be empty and you car hear the fuel pump winding a little bit. Any ideas? Thanks

[jlevie]

It would help to know what car you have.

If the car is an 325i/is/ic with the 63L tank it could be a stuck or shorted level sensor. If it is a car with the 55L tank it could be that a cluster from a car with the 63L tank was swapped in without changing the fuel gauge.

[NickMav]

Yeah sorry, its a 91 318is. The previous owner did replace the dash but im not sure if he kept the old cluster or not

[jlevie]

I'm going to go with your car having the wrong fuel gauge in the cluster as your car has the 55L tank with a single level sensor on the right side.

[Gregs///M]

You can swap the fuel gauge from the correct car's cluster. They are interchangeable.

[McGyver]

i would suspect the level sensors. my car did the same thing with the original gauge and the new cluster i put in. you will have a level sensor in the pump hole, and may have another one in the hole on the other side. look up the voltages in the bently and check them with a full tank of gas.

[NickMav]

alright thanks guys, im going to test the volts first on the level sensors. If thats good then i dont know, buy a new fuel gauage i guess. My gas light does comes on right before 1/2 tank and i havent ran out yet but im pretty sure at dead 1/2 it is completly empty if thats any help.

[NickMav]

It would help to know what car you have.

If the car is an 325i/is/ic with the 63L tank it could be a stuck or shorted level sensor. If it is a car with the 55L tank it could be that a cluster from a car with the 63L tank was swapped in without changing the fuel gauge.

The 325 has the 14.5 gallon or 54.9 Liter tank and the 318 has the 16.4 Gallon tank or 62.1 Liter tank. I havent had any time to check anything since i made this thread and i finally looked it up and the 91 318is has a single sending unit part no 16141152266. The sending unit is around 140 dollars and i think thats the problem. If my gauge is empty at exactly 1/2 tank then i dont think its the gauage because a 1.9 Gallon difference would not make up a whole half tank, if it was the gauge the car would be empty right around before empty. Im going to try out the new sending unit and let you know what happens.

[jlevie]

The 325 has the 14.5 gallon or 54.9 Liter tank and the 318 has the 16.4 Gallon tank or 62.1 Liter tank. I havent had any time to check anything since i made this thread and i finally looked it up and the 91 318is has a single sending unit part no 16141152266. The sending unit is around 140 dollars and i think thats the problem. If my gauge is empty at exactly 1/2 tank then i dont think its the gauage because a 1.9 Gallon difference would not make up a whole half tank, if it was the gauge the car would be empty right around before empty. Im going to try out the new sending unit and let you know what happens.

Close... 325 US cars had a 55L tank through 8/87. After that they all had 63L tanks. Very early 318 US cars had a 58L tank until 9/83. After that they all have 55L tanks.

For a 55/58L tank, if the crossover tube between the tank halves is plugged with rust, the gauge can read empty or nearly empty when the tank is really about half full. Fuel gets sloshed into the left side of the tank and can't get back to the right side where the pump and sensor are. The 63L tanks use the returning fuel to operate a siphon to accomplish what the crossover tube does.

[NickMav]

Close... 325 US cars had a 55L tank through 8/87. After that they all had 63L tanks. Very early 318 US cars had a 58L tank until 9/83. After that they all have 55L tanks.

For a 55/58L tank, if the crossover tube between the tank halves is plugged with rust, the gauge can read empty or nearly empty when the tank is really about half full. Fuel gets sloshed into the left side of the tank and can't get back to the right side where the pump and sensor are. The 63L tanks use the returning fuel to operate a siphon to accomplish what the crossover tube does.

Replacing that hose might actually solve this, I didnt even think of that and now that i remember when i was under there last time doing some stuff i did notice it was pretty rusty and probably clogged. So the pump and sensor are on the right side with the cross over tube that connects them. Nothing is on the left side then? When i had my seat off i noticed that the left side had a cover as well as the right side.