YAY!!! lets troubleshoot fuel gauges

[Vombrown]

After helping a friend in his shop for a few days troubleshooting an older ford for a few hours I remember commenting, I'm glad that's over. Well.....
Took the 82 gm out for the first testdrive since buying it and going through everytbing. Fuel gauge is pegged to the right. Went and checked the diesel level And one tank was half full while the other saddle tank was full. Switch doesn't change anything.

I'm don't remember whAT the most common issue is with this system. Switch or divertor valve?

 

[rampage]

Check to see if the ground wire for the sending unit is broken at the fuel tank.

 

[6872xtc]

Depending on which switching valve you have, the wire for the gauge is either switched at the valve, or at the dash switch.
Pegged to past full means no connection, basically, but with both tanks doing the same, I would guess that it isn't a sender issue, unless they both have problems.

If the dash switch says "depress fully " , I believe that has the sender wires going to and through the switching valve. Does the valve work? Does it switch tanks, or make any noise? Leave the engine off and flip the switch and see what you hear.

 

[Vombrown]

Didnt have time to troubleshoot it today. Ill be on it like a fat kid on a cupcake tomorrow.

 

[diesel4me]

CHEVYTRUCKS.ORG - Troubleshooting Your Gas Gauge