fuel gauge freakin out!

[drewroq]

Has this ever happened to anyone, fuel level gauge is moving erratically when I get on the gas from a stop or from a slow roll, but when I start to level off on the gas or I'm just cruising it rests back to the correct fuel level again. I'm guessing maybe a bad sending unit what do you guys think?

 

[fast eddie]

ck your grounds always a good start,problem area on these old cars

 

[Crazi]

by moving erratically, do you mean reads about a quarter tank or so lower?

I just fixed my gauge and it still does that. I think it is normal if that is what you are refering to.

 

[drewroq]

no, my problem is that the needle shoots all over the place until the car starts to reach a steady speed (fast or slow), then it settles to where the correct fuel level is.

 

[Crazi]

Sounds like you got a wire pinched or something. Do you still have the stock tank and sender? Try pulling the gauge out and cleaning the three posts that plug into the dash. It really isn't that difficult...

 

[kevans]

Happens all the time...pull the cluster panel and use some sand paper to clean the terminals on the fuel guage. Will help but not necessarily cure it.

Kev

 

[ez at nova]

Just reviving this rather than posting a new one. I have the same issue...fuel level is way wrong and flies all over until I cruise on the highway for a while at a steady speed, then the level seems right. Major PITA when I'm trying to get down to next to no gas to put in race gas.
Anyone have any new input? I haven't taken the cluster off yet to clean the actual guage pins. How do I get in there...just pull? I don't want to break anything!
For what it's worth, the pump, sending unit, plug back there, and tank are all fine...I've swapped them all thinking it was the root cuase, but no change!


Thanks!

 

[GN Bob]

I had the same problem, needle was all over the place with 1/4 to 3/4 tank. Took apart fuel guage in the dash and cleaned the posts and the plug in terminals, cleaned the sender wire connections at the pump plug too. Still no good.

The sender unit was bad and no longer available, called a few vendors and was quoted $100 - $150 for old stock units.

I rebuilt mine and its fine now. I can rebuild yours with new parts if you are interested.

 

[ez at nova]

Bob,
Interesting... I'm skeptical that my sender is bad though. I pulled it out and VERY slowly, by hand, moved the float up and down and the guage moved as it should. We then swapped on another sending unit to compare and that was actually more innacurate than mine! BUT, back in the tank, driving around, the guage is still innacurate.

 

[GN Bob]

Did the float move easily, could it be mechanically hanging up as gas sloshes around in the tank?

I don't recall if the float is hollow soldered metal or foam, hollow metal could have a hole in it and partially fill up with gas screwing up your readings.

You can try measuring the resistance at the plug under the bumper. I believe it should read 0 - 90 ohms, I'm guessing that 0 is empty tank, 90 full.

If thats OK then measure the resistance at the pin in the dash.

Good luck.

 

[ez at nova]

I know it wasn't a foam baffle (someone should know the answer to this) ...I almost think it was hollow plastic, but maybe it was metal, and we checked for any gas in it when we took it out. Also, I remember it moved VERY easily up and down.

 

[salvageV6]

It is an electrical bridge circuit that is supposed to be neutral to any changes in the cars voltage from the alternator.

Yours appears to work well not due to the level conditions of highway driving but perhaps due to the constant voltage output at that highway speed.

Perhaps the bridge circuit is damaged and now voltage dependant and varying due to alternator varying at typical speeds.

Maybe... bridge circuitry is part of the dash I believe.

 

[skturbo]

The float in a GN is a hard foam. I've had a couple GNs come in with the same problem. The plastic tub the fuel pump sits in came lose and was moving around. You might want to check that.

Steve K.

 

[ez at nova]

Plastic tub?? I remember the tank had a hole in the top, the pump detatched and got lifted out...but I don't remember any tub?? I just looked in the tank and could see the baffles, but...am I missing a part?

 

[J Banning]

I'm experiencing fuel level problems as well.

As someone else has already mentioned, I also took out my pump and slowly moved the float (appeared to be hollow plastic) by hand. The dash gauge moved fine. I put it all back together, and it's still messed up. I can fill up the tank and then run it dry but hte gauge will only move between 1/2 & 1/4 tank. I then replaced the gauge in the dash with a known good piece. No change there either?

I'd try replacing the sender with another, but the problem with that is that mine has a second pickup tube brazed in place for my external Bosch pump. To put a stock pickup in, I'd have to remove the pump and put new fuel lines in.

I'll try removing the gauge again and cleaning the connections. Aside from that, what else should I try? If the float was bad, wouldn't it completely fill up and make the gauge read empty all the time?

I'd really like to get this fixed. Not knowing how much gas I've got and having to fill up "just in case" every 100 or so miles is a complete pain in the a**.

Any suggestions?

-Banning.

 

[ez at nova]

You mentioned trying to clean the pins again, but how could your connector pins be dirty if, like you said, you took out the pump and moved the float and the needle moved fine (as did mine!)? This is SO frustrating!

 

[monte_383]

ez - I was thinking that the CEL fix for P0424 (catalyst efficiency) on your WRX would work. Essentially slowing down the voltage fluctuations going to the guage. May work like the the bridge circuit slavagev6 is talking about. -Chuck

 

[kidreynolds]

Has anyone found a fix for this problem

Thanks
Brent