The Stovebolt Site Forums The Shop Area The Electrical Bay Gas gauge issue 49 3600

So brand new gas gauge and a new sending unit. It all worked fine out of the dash with ground wire hooked up. Unhook the wire to the sending unit and it showed full then I grounded the wire and it showed empty. One caveat, to make it work correctly I had to hook the sending unit to the full side of the fuel gauge in the ignition to empty side. Bad news, after installing back into dash nothing reads on guage. Hope someone knows what I need to change. Thanks

recheck your connections, particularly the grounds. you might have pulled a wire loose too. Is the gauge grounded to the dash?

Yes I checked the ground for gauge to cluster before I installed in dash.

I've been reading past post and I think I may know the problem. Someone said a new gauge had a needle drag on the cover. Just went out with a flashlight and it's definitely against the case. darn I hate taking it out again. But I'm hoping that is the problem. I'll report back.

That was the problem. Took it out and bent the interior part of the labeled cover to make clearance on all the needles. Most likely the new guage was just a little larger than the old one. Put it back together and when I pull the wire from the sender it swings to full and when tough ground it swings to empty. Connected to the sender it shows just over half and that is pretty close.

Btw, I mounted a mirror on the firewall side so I could see everything while reaching under the dash. Wow did that make it easier than trying to get my head and arms under the dash.

The first thing to do when doing under dash wiring is take the seat out. Then use a cinder block and a long piece of 1 X 12 lumber to lean/lie on. Then the only difficult trick is to keep from falling asleep!
Jerry

I also have an issue with my gas gauge.
It goes off normally ( to E) ,but with key on the range is between just below half when low on fuel to 3/4 when full.

Original gauge and original sender?

If replacement sender, what is the ohm rating?

original gage , replacement sender, will check ohm rating

OK

the original gauge was 0-30 ohms
A "12 volt" replacement sender might be rated 0-90 ohms.

There are replacement gauges that use the original rating, and, there are replacement gauges are made to work with the newer/higher rating.

Mis-matched sender/gauge could give the readings you describe.

I did order 12v replacement gages and sender unit but when I get the chance I'll pull seat out and check ohms showing at tank.
Do I need to sending unit out of tank? Last time I tried it wouldn't come all the way out. (not sure how I got in in)

What goes in, must come out..lol

You cannot "take" them out. They only come out when THEY want to come out. I feel your pain.

I've encountered at least three different AD trucks over the years that had dirty contacts in the ignition switch which would allow all of them to give a higher than normal reading on the gas gauge. On the first two trucks I took the ignition switches apart to clean the contacts. On the last one I just turned the switch on and off a bunch of times with the key which did the trick. You can check the switch for continuity with a meter looking for 0 ohms. The dirty contacts also cut proper voltage to the ignition circuit.