Fuel Gauge Stuck on 1/2 Full (Page 1/1)
labbe001 MAR 18, 12:15 PM
Hi All
I purchased an 87GT a little while back. When I bought the car, the fuel gauge was pegged to empty. I pulled the tank, located the wiring issue and all has been well since. Until yesterday. When pulling out of the gas station after filling up, I noticed the needle creeping towards full. Then all of the sudden, it dropped backed to a little over half full. Later in the day, I went out for a drive. As I'm going down the road, the needle starts creeping towards full then drops back to just below half a tank and stays there no matter what. I pulled the C502 connector on the fire wall and ohmed the hot and ground going to the sending unit. My meter is reading 93Ohms which is above the 90 Ohms of resistance that the sending unit is spec'd for. Any thoughts?
olejoedad MAR 18, 02:05 PM
You checked resistance on the pink wire (B) to (A)?
theogre MAR 18, 03:06 PM
93Ω from the sender is fine.
Spec is "0 - 90Ω" but most read a bit high when full & often the gauge reads a over the full mark too.
But Gauge etc should say Empty a bit sooner Before the F-pump actually sucks air because that can quickly destroy the pump.

Have gauge(s) problems can be a bad gauge but often wiring problem(s) somewhere.

See https://www.fiero.nl/forum/Forum2/HTML/146784.html Fuel, Engine Temp or Oil Pressure gauges have problems?
maybe http://www.fiero.nl/forum/Forum2/HTML/138175.html Instrument panel bulb layout too & clean the white & orange "guts" where dash lights work.


------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

[This message has been edited by theogre (edited 03-18-2024).]

labbe001 MAR 18, 05:17 PM

quote
Originally posted by olejoedad:

You checked resistance on the pink wire (B) to (A)?



Yes….I Ohmed the Pink and the black at the C502 connector and got 93 Ohmes of resistance.
labbe001 MAR 18, 05:23 PM

quote
Originally posted by theogre:

93Ω from the sender is fine.
Spec is "0 - 90Ω" but most read a bit high when full & often the gauge reads a over the full mark too.
But Gauge etc should say Empty a bit sooner Before the F-pump actually sucks air because that can quickly destroy the pump.

Have gauge(s) problems can be a bad gauge but often wiring problem(s) somewhere.

See https://www.fiero.nl/forum/Forum2/HTML/146784.html Fuel, Engine Temp or Oil Pressure gauges have problems?
maybe http://www.fiero.nl/forum/Forum2/HTML/138175.html Instrument panel bulb layout too & clean the white & orange "guts" where dash lights work.





Gotcha….yeah now that you mention it, it was reading a little over when I had the sending unit out and was bench testing it.


So I just went for a 20 min drive with no issues….until a was about a minute from home and the gauge dropped back down from proper reading (full b/c the tank is full) to just above half a tank. I disconnected the C502 and the gauge goes to above full (as it should) I Ohm the sending unit and it’s still showing 93 ohms of resistance. When I plug the C502 back up, the gauge goes to just above half a tank.