FUEL GAUGE NOT WORKING CORRECTLY

john saleeby

Active Member
I fill the tank and cannot see fuel gauge needle at all. Drive about 160 miles and needle goes to half.

Is my fuel sender most likely bad (87 GN with 56K miles)?

What fuel senders are folks using? I have a Walbro 340 pump with hotwire kit.

Thanks for input and advice on changing out sender if that is the most likely problem.
 
I fill the tank and cannot see fuel gauge needle at all. Drive about 160 miles and needle goes to half.

Is my fuel sender most likely bad (87 GN with 56K miles)?

What fuel senders are folks using? I have a Walbro 340 pump with hotwire kit.

Thanks for input and advice on changing out sender if that is the most likely problem.
Mine went bad at about 65k miles. New sending is probably due.


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Drop the tank and do a sweep test on the sending unit. Regardless the tank needs to come down . Racetronics has a real nice new sending unit for a an style hose or for stock hoses the Buick venders will carry it.
 
From what I've seen, the resistance in the 30 year old wiring is causing a lot of the issues. I just record into my phone the mileage I fill up at, and 250 miles later, I fill again.
This doesn't answer your question either, but I thought it was enlightening, at least for me:) I put a new Turbo Tweak pump and hot wire kit in my black car today. When I was done, with the original wiring, I had 37#'s FP hose on. When I plugged in the hot wire kit, I had 45#'s hose on.
Now, maybe, TT has a hell of a pump, or I'm getting the volts that I need at the pump. Since the Walbro 255 was also doing 37#'s, I'm thinking the wiring.
And yeah, the fuel gauge still ain't right:punch:
 
My gauge started working intermittently after I changed my fuel pump on my '86 T. Dropped the tank again and pulled the pump and rheostat assy back out.. Cleaned the rheostat and the wire connectors (after separating them) with electronic parts cleaner, and then tested it out of the car. It went back to working like new. Put it back together and never had any more problems and it read completely true. Seems like the electrical interfaces in the tank get some kind of film on them. Do what GBGN1 suggests, but before you change to something new, try cleaning everything first. May save a few bucks and it only took me an hour and a half to fix it.
John
 
when my fuel gauge was giving me troubles I did the above, and found I had to pull the cluster and clean the connector that plugs into the back of the cluster. I'd done the sweep test on my sender so I had a good idea it was okay.
 
Don't just start throwing parts at a problem. Test first, then don't replace what passes.

John Spina has an article somewhere showing how to clean the contacts inside the dash assembly.

and when I replaced my tank, I identified a design flaw with the stock sender and fixed it. Now my gauge will show fuel slosh) Oh, yeah... original sender with over 250,000 miles and was 'lucky' enough to sit in rust for 10 years after my car was stolen....

Photo1484.jpg

Basically, you run a ground wire to the arm so that the other half of the circuit is fully connected.
The way the factory has it, the ground comes from where the arm passes through the metal box and it gets what it can get. Nowhere near 0 ohms at all times.
 
When I do a "Sweep" test, confirm I leave the harness plugged in, turn key to on position without starting car and have a friend look at my fuel gauge while I move the float? Thanks for the tips. Someone please confirm this is the correct procedure.
 
I think the sweep test involves checking resistance with a meter. Try googling "how to ohm a fuel sending unit" and utube videos will magically appear. I bent the arm a bit inward (instead of a 90 degree angle it is now more like a 75 degree angle,) to get a more accurate reading on the gauge. So now when the tank is full, the needle just barely goes past full on the gauge. But I have an Autometer gauge so your mileage may vary.
 
I fill the tank and cannot see fuel gauge needle at all. Drive about 160 miles and needle goes to half.

Is my fuel sender most likely bad (87 GN with 56K miles)?

What fuel senders are folks using? I have a Walbro 340 pump with hotwire kit.

Thanks for input and advice on changing out sender if that is the most likely problem.
Half way at 160 miles sounds about right. At 20 mpg you used about 8 gallons, or 1/2 tank
 
I wouldn't worry so much about the reading on the full side. The empty side is a little more important.

I did notice that when I did that wiring mod to my hangar, the reaction time is a million times better... but not I can't run the car will below E anymore. On the upside I've learned I can drive about 4 miles while running out of gas!

Not the best thing for my pump though.
 
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