Question about 1986 Chevrolet C3500

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My 86 1/2 ton chevy tank selector wont work and fuel gauges show past full

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  • 43 Answers

Sending unit wire is grounded or sending unit in tank is shot.

Posted on Nov 17, 2013


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Posted on Jan 02, 2017

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SOURCE: 2000 chevy blazer fuel gauge

did you recently change the fuel pump? If so you needed to change the wire harness thats attached to the fuel pump, then if not, your floater need to be replaced inside your fuel tank.
How do I know? from experience.

Posted on Aug 19, 2009

  • 497 Answers

SOURCE: 2002 Chevy Suburban: Fuel gauge reads empty, tank is half full

Youre gauge is controlled by a plunger in the fuel tank which is attached to the sensor and the fuel gauge. it sounds like when the plunger goes down half way its either getting stuck down lower then it should. Needs replacing. Any mechanic can do this install for you.

Posted on Aug 27, 2009

  • 117 Answers

SOURCE: 1990 chevy van G20 gas gauge shows full at all

The float inside the tank needs to be replaced. or one of the wires has a small short in it.

Posted on Dec 21, 2009

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SOURCE: The gas gauge on my 2002 chevy venture is not

Your tank sending unit is bad. Unfortunately, it is part of the fuel pump assembly, and the part costs around $400, give or take. plus installation labor. It is an all too common problem on GM vehicles, as I have had to change it on my last 2 GMs. If you do an internet search you will find plenty of others in the same boat!

Posted on Apr 23, 2010

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SOURCE: 2003 chevy silverado, fuel gauge started registere...

Common problem on the 03-06 Silverado instrument clusters for the fuel gauge to go out. It's usually caused by one of two main problems, either the stepper motor on the cluster's circuit board is going out or the sending unit on the fuel pump is going out. Check out this blog post about the problem - Silverado fuel gauge problems

Posted on Sep 30, 2010

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1 Answer

Fuel Gauge wont move past 3/4 tank even with full tank

There is no easy fix.
Either the gauge on the dash is faulty, or the sending unit in the tank.
The sending unit uses a float which may be getting stuck at the 3/4 mark.

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My fuel selector valve is out on my 86 gmc 3/4 ton truck and was wondering if i could just tie both my tanks together as one

It depends on wheter or not your truck is fuel injected or carbureted. If it is fuel injected I'm pretty sure that you have an electric fuel pump in each tank so that wouldn't work. If yours is carbureted you should have a manual fuel pump and with a little plumbing you could probably make that work. I've never tried it before though.

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My 2003 one ton Chevrolet Silverado Dually has two gas tanks that are suppose to syphon together. No switch, but only one tank is working right, the rear tank, the one with the fuel gauge always shows full...

In regard to sender unit. Soak it in vinegar for a couple hours. Works awesome. I did this to my chevy pickup sender unit and now it works awesome. The problem is usually condensation over the years corrodes the brass wiper/rheostat. Vinegar is a mild acid and works excellent.

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I have a 1986 chevy 1/2 ton. the fuel gauge wasn't working so i replaced the sending unit and now when the tank is full the gauge reads at only 1/4 tank...any ideas? i was thinking maybe the gauge itself...

When you changed the sending unit, was this in the tank? or does it have a manual that bolts to the block. If it is on the block, drop the tank (or take the bed off) and replace the float.


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Apr 30, 2010 | 1986 Chevrolet C1500

1 Answer

86 chevy truck fuel gauge reads past full and i know its only half full

Check the ground wire for the fuel gauge sending unit, at the tank. They get rusty. Hope this helps.

Feb 27, 2010 | 1986 Chevrolet C3500

1 Answer

86 chevy 1/2 ton 4x4,gas gage reads way past full all the time.even when tank is empty.

you have a ground problem check the wiring at the sender it may be broken off or no a good enough ground to the frame it should be a black wire
hope this helps

Nov 05, 2009 | 1986 Chevrolet C1500

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My f350 1997 will not run on the rear tank . how do i go about finding what the problem is?

well, first, to find out if its the in tank fuel pump or the tank selector valve, the cheapest and probable easiest thing to do is find the selector valve under the truck and switch the incoming fuel lines. front tank to rear tank inlet, and vice versa. If the truck still doesnt run, you either have an electrical delivery problem to the in tank fuel pump or a bad fuel pump. If after switching the lines, it does run, then you need a new selector valve

Sep 23, 2009 | 1997 Ford F350 Crew Cab

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1985 Dodge Ramcharger fuel gauge not working

The problem most likely is not the gauge itself. It could be faulty wiring between the gauge & sending unit, or most likely a bad sending unit in the tank. Visit, do a thread search on fuel gauge issues, and you'll find a ton of info. If you need anything clarified, post up on the vehicle help board...the members there are happy to help!

Jun 07, 2009 | 1985 Dodge Ramcharger

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Fuel issue 1985 pickup

did you change the pump with gauge cluster may have put bad pump in. some gauge clusters have built in pumps

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