Help on 86 gmc sending unit

[utah86gmc]

I have had this 1986 1/2 ton 4wd GMC for several years. The fuel guage never worked. I only drove it for the hunting season so I never worried, always just kept a few gas cans in the back. In 6 years I have only put on 13,000 miles.

It has the two twin tanks, it doesnt matter which tank I switch to the needle is horizontal left all the time. I tried a new dash gauge that a friend gave me it didnt work . I just assumed it must be in the sending units that I knew were alot of money so I never worried. Now I am starting to drive it everyday and a fuel gauge would be nice.

Can anyone give me any detailed instructions on testing the sending units before I spend over $100 bucks a shot for 'em. I am not an auto mechanic but I am an HVAC technician for over 10 years so I am well trained in electrical diagrams and trouble shooting. I just cant find any info.

Any help would be appreciated.

[mrjohnwayne]

Most of them run from a simple reostat I guess you could call it. An ohm meter or a multimeter can get the job done by meausring resistence across the sending unit. Hope this makes sence.