Does anyone's gas gauge actually work?

[VinniE30]

Gas gauge is wacky on both my e30s. accurate enough but gets crazy when below a quarter tank. Never been stranded but knock on wood.

[hogdacb750]

mine no workie. dosen't the obc have a est for your gas or distance ?

[jlevie]

Mine works halfway perfectly. I almost got stranded by it.


it is very reliable. at 1/2 tank, you are actually empty.

I got pissed off one day cause I heard this loud whine from the back end of the car, and I knew it was from the fuel pump. A few miles later the fuel light came on, but the gauge read 1/2 tank...? I figured what the heck I will fill it up. Sure enough, the car was nearly bone dry, and the FP whine stopped once I got fuel in the tanks.

A common cause of that is a fuel gauge meant for a late 63L tank with two level sensors used with a 55L tank and a single sensor (from a cluster swap). The sensors for the 63L tank and wired in series and result ~120 ohms when the tank is empty. So if that gauge with a single sensor the tank will be empty when the gauge reads half.

Your 91 318i has the 55L tank and a single sensor, so I suspect you have the gauge. This can also happen when the car has the 63L tank (and the correct gauge) when one of the level sensors is stuck at the top (zero ohms) or shorted. If that happens to the left side sensor the low fuel warning light will still work. A stuck right side sensor will disable the light.

[Raxe]

Mine have always worked fine and been accurate.

[Gregs///M]

Here are some tips for you guys with gas gauge and coolant gauge problems. This assumes you have tested the sender's via Bentley manual specs and procedures.

1. I would first pull the cluster out and tighten the 7mm grounded nuts directly behind each gauge. This is the primary ground for each gauge.

2. Above the brake pedal, under the dash, there is a bracket with two 10mm nuts on it. The upper nut is the ground rings for the cluster. The bottom nut is the ground rings for the power windows and illumination circuits. I recommend that you remove these two nuts and clean each ring lug as well as the ground stud with a wire brush. After 20+ years, these can corrode. Don't just look at it and assume it is OK. You must actually remove them and inspect each side of the ring lugs. You might find your cluster gauges become more accurate (if grounds were corroded) and your windows travel faster.

3. This applies mostly for the coolant gauge. Check the condition of the Engine to Chassis ground cable. On the M20, this mounts from the oil pan to the frame rail on the drivers side. This cable can be corroded and oily from so many years. Replacing it would help electron flow. The cable can be be cleaned enough to crank the starter over because of the huge current load, however it can cause electrical resistance in the circuit if dirty, causing inaccurate coolant temp feedback. This cable provides the primary ground loop for all engine related electronics.

4. Lastly, if these tips do not work. I would look into cluster inspection. The cluster main board is well known to develop cracked solder joints that are so small you might need a magnifying glass to it them. Also the gauge themselves can develop the same.

5. Measure voltage across SI board batteries. Each battery should be a minimum of 3 volts DC. Each current load should be 300mA minimum. Current load must be tested with the batteries removed from the circuit/SI board.

6. If all else fails, inspect the physical wiring. Measure resistance across the wire, you should see near 0 ohms and no breaks.

Good luck, hope that helps.

[chance]

A common cause of that is a fuel gauge meant for a late 63L tank with two level sensors used with a 55L tank and a single sensor (from a cluster swap). The sensors for the 63L tank and wired in series and result ~120 ohms when the tank is empty. So if that gauge with a single sensor the tank will be empty when the gauge reads half.

Your 91 318i has the 55L tank and a single sensor, so I suspect you have the gauge. This can also happen when the car has the 63L tank (and the correct gauge) when one of the level sensors is stuck at the top (zero ohms) or shorted. If that happens to the left side sensor the low fuel warning light will still work. A stuck right side sensor will disable the light.

I just met the owner before the previous owner of my car. He said something about the PO putting an Audi fuel pump in the car? Also, the cluster currently in the car is from a metal bumper car so that might be it..

[e30Villain]

Here are some tips for you guys with gas gauge and coolant gauge problems. This assumes you have tested the sender's via Bentley manual specs and procedures.

1. I would first pull the cluster out and tighten the 7mm grounded nuts directly behind each gauge. This is the primary ground for each gauge.

2. Above the brake pedal, under the dash, there is a bracket with two 10mm nuts on it. The upper nut is the ground rings for the cluster. The bottom nut is the ground rings for the power windows and illumination circuits. I recommend that you remove these two nuts and clean each ring lug as well as the ground stud with a wire brush. After 20+ years, these can corrode. Don't just look at it and assume it is OK. You must actually remove them and inspect each side of the ring lugs. You might find your cluster gauges become more accurate (if grounds were corroded) and your windows travel faster.

3. This applies mostly for the coolant gauge. Check the condition of the Engine to Chassis ground cable. On the M20, this mounts from the oil pan to the frame rail on the drivers side. This cable can be corroded and oily from so many years. Replacing it would help electron flow. The cable can be be cleaned enough to crank the starter over because of the huge current load, however it can cause electrical resistance in the circuit if dirty, causing inaccurate coolant temp feedback. This cable provides the primary ground loop for all engine related electronics.

4. Lastly, if these tips do not work. I would look into cluster inspection. The cluster main board is well known to develop cracked solder joints that are so small you might need a magnifying glass to it them. Also the gauge themselves can develop the same.

5. Measure voltage across SI board batteries. Each battery should be a minimum of 3 volts DC. Each current load should be 300mA minimum. Current load must be tested with the batteries removed from the circuit/SI board.

6. If all else fails, inspect the physical wiring. Measure resistance across the wire, you should see near 0 ohms and no breaks.

Good luck, hope that helps.

Wow thanks! Gona tackle all these this month.

[trackjunkie21]

So not down to spend 90 bucks. Rather put that towards wheels.

dumbest shit I've ever heard.

[stamar]

if the mpg on the computer is also out, doesnt that also eliminate the guage nut beign off and point the finger at one of the sending units?

[e30Villain]

dumbest shit I've ever heard.

You must be one retarded little girl.

[2761377]

You must be one retarded little girl.

what is with being cheap? it's a theme on this site. must be related to youthful poverty. yet $90 won't even buy two tanks of gas. speaking of that you probably use 87 octane so maybe you could fill twice.

BMW's are expensive- if you can't afford to maintain it properly sell it and buy a toyota

[Thehemiman]

Mine only registers in 1/4 amounts...it will sit at half for a while, then bounce to 1/4 one day but its always been consistent.

[stamar]

what is with being cheap? it's a theme on this site. must be related to youthful poverty. yet $90 won't even buy two tanks of gas. speaking of that you probably use 87 octane so maybe you could fill twice.

BMW's are expensive- if you can't afford to maintain it properly sell it and buy a toyota

Ya you tell em.

Im personally dying to meet people who spend 1000s on maintenance on old rusty heaps from the 80s.

Youre a bawler bro you have a crappy old bmw.

kind of like playskools my first luxury car. You can practice dumping money on random stuff. and paying th 95$ shop rate too. Breaks down a lot so you can practice.

sending unit 200$ fixed out the door baller.


i gott news for you dude, if you think like that this is not the car for you. You need to know where to get parts for cheap and do it yourself or theres no point. Your cars not worth a fraction of what you think it is.

[FunfGan]

Gas gauge is wonky on my car too. But I get less than 15mpg, so it's not really much use anyway...

[TimKninja]

So not down to spend 90 bucks. Rather put that towards wheels.

You must of Been a Volkswagen Owner.

Welcome to owning an e30. They always jump around.

all of my E30s have had good working gauges. This is my first e30 where the gas light actually works.