blackandgold51
1/2 ton status
After I had put anew fuel pump in the fuel gas meter has been stuck past full for a few days
CK5
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1990 Suburban V1500 gas gauge not working. Needle stuck past "Full".
- Thread starter blackandgold51
- Start date
How full past full? Like 3 o'clock position?
blackandgold51
1/2 ton status
Yes
Disconnect the fuel pump/sending unit plug near the tank. With the truck in "run" (but not started) does the gauge stay in same spot? Now ground the wire in that plug for the gauge (not the pump one of course) and see if the needle moves to the opposite side.
If the gauge pegs out both directions with the above instructions, then everything forward of that connector is working properly and the problem is the sending unit or sending unit wiring behind that connector. Pretty unlikely the sending unit itself is faulty, they don't peg the gauge when they are overfull even. Most likely looking for a bad wire/connection.
I assume the truck runs, so your tank ground has to be good.
If the gauge pegs out both directions with the above instructions, then everything forward of that connector is working properly and the problem is the sending unit or sending unit wiring behind that connector. Pretty unlikely the sending unit itself is faulty, they don't peg the gauge when they are overfull even. Most likely looking for a bad wire/connection.
I assume the truck runs, so your tank ground has to be good.
The gas gauge in my pickup pegs at 3 o'clock and stays there unless its about to run out of gas,then you might see it dip towards empty for a few seconds and slowly come back up over the full mark..
I unplugged the sending unit and grounded the one for the fuel gauge and the needle didn't budge (with the key "on")---then plugged the wires onto a "known good sending unit" I had lying around,and I grounded it,when I move the float on it up and down,the gauge reads correctly..so the grounding the sender wire test doesn't always work I guess,at least not on my truck,which had a dual tank setup that was completely butchered..
If you do a search here under fuel gauge problems,I posted a link on how to test GM gauges--I cant seem to find it in my saved files,it might have gotten deleted..
I unplugged the sending unit and grounded the one for the fuel gauge and the needle didn't budge (with the key "on")---then plugged the wires onto a "known good sending unit" I had lying around,and I grounded it,when I move the float on it up and down,the gauge reads correctly..so the grounding the sender wire test doesn't always work I guess,at least not on my truck,which had a dual tank setup that was completely butchered..
If you do a search here under fuel gauge problems,I posted a link on how to test GM gauges--I cant seem to find it in my saved files,it might have gotten deleted..
Dual tank setups are absolutely terrible to deal with. The switch coupled with the variety of solenoid setups they used, with emissions requirements, made for a complex system.
Luckily for the single tanks, there is nothing between the gauge and the sender except wire. If everything is operating properly, open and shorted to ground, the gauges have to peg either direction, that's how they work. If they don't respond like that when grounded/open, there is certainly something wrong. At least ground/open test at that plug will tell you which side of the vehicle you need to focus on.
For general info, the oil pressure and water temp gauges work exactly the same, and can be tested the same way.
When I first got my '82 someone had taken out the dash switch,and the switch at the tank to switch over which tank you wanted to use,and had installed a manual shut off under the truck,and all the wiring was either cut off or left hanging !..there was also a new looking electric fuel pump mounted under the cab crossmember,with no wires or hoses hooked up on it !..(I decided to plumb that in to aid in bleeding fuel filters ,it worked OK,no idea why they left it there un-used)..
Since one of the tanks leaked anyway,(passenger side),I just used one of them,found the wire going to the gauge on the RH tank,which was either tan or pink,and ran it to the sending unit on the LH tank,and
ta-da,it decided to work..
Years later that tank rotted thru,so I took the RH tank right off that was not being used & junk and scrapped it,and mounted a good used tank on the drivers side...only bummer was after I got it all installed,I discovered the sending unit was junk!...
I'm not into dropping the tank again to install one of the good used senders I have,instead I just top off the tank weekly or when I am going to be going a decent distance,and write the mileage down..
Out of 30+ vehicles I have owned,maybe half of them had a working gas gauge,or one that you could trust to be "accurate"..sucks not knowing how much fuel is really IN the tank!..
Since one of the tanks leaked anyway,(passenger side),I just used one of them,found the wire going to the gauge on the RH tank,which was either tan or pink,and ran it to the sending unit on the LH tank,and
ta-da,it decided to work..
Years later that tank rotted thru,so I took the RH tank right off that was not being used & junk and scrapped it,and mounted a good used tank on the drivers side...only bummer was after I got it all installed,I discovered the sending unit was junk!...
I'm not into dropping the tank again to install one of the good used senders I have,instead I just top off the tank weekly or when I am going to be going a decent distance,and write the mileage down..
Out of 30+ vehicles I have owned,maybe half of them had a working gas gauge,or one that you could trust to be "accurate"..sucks not knowing how much fuel is really IN the tank!..
