Fuel gauge not working 88 crew r20

[Qwk]

Found this thread using the SEARCH feature. Hopefully it helps me figure out my Higher than Full reading on my fuel level gauge.

 

[chengny]

Is this only when the tank is full or does it always peg high even when the tank is nearly empty.

If it only reads high when the tank is nearly full that is normal. Due to the design of these tanks (a domed top) the gauge will read at the top of the scale until the level drops below the dome. So for maybe 20-30 miles you will feel like you're getting insane good gas mileage. After that, reality sets in and you are back to 12 mpg.

But that probably is not your situation right? Your gauge always reads at the top no matter how low the actual level.

If you need help, come back. Someone will know what to do.

 

[Qwk]

Is this only when the tank is full or does it always peg high even when the tank is nearly empty.

If it only reads high when the tank is nearly full that is normal. Due to the design of these tanks (a domed top) the gauge will read at the top of the scale until the level drops below the dome. So for maybe 20-30 miles you will feel like you're getting insane good gas mileage. After that, reality sets in and you are back to 12 mpg.

But that probably is not your situation right? Your gauge always reads at the top no matter how low the actual level.

If you need help, come back. Someone will know what to do.

Thanks!
It reads below the Full, so if you are looking at it and the top is 12 o clock, the pointer is stuck pointing at 3 o clock. I think we got it pegged as a bad gauge. HOPEFULLY, the new gauge does the trick.

 

[chengny]

You should check the ground connection from the fuel tank sender to the frame.

If this ground wire is broken or is loose/corroded at the frame bolt or sender tab there is no path to ground for the "E" side electromagnet in the gauge. Consequently the electromagnet that drives the "F" side will be stronger and pull the needle to it's pegged high position.

My money would be a bad sender to frame ground wire - happens all the time as these trucks turn 30 years old. The fuel gauges on the other hand rarely fail in comparison.

There will be a short black (or blue) wire that connects the sender head to the frame. At least look at it before buying a new gauge and tearing the instrument panel apart.

Always check the simplest and cheapest stuff first.

 

[Qwk]

Could be a number of things. Find the pink wire going to the sender in the tank and ground it out when the ignition is on. If the gauge goes to empty, then unbolt the ground wire from the frame and clean the connection. If the gauge still doesn't work it's probably a bad sending unit.

Trying that now, will report back.

You should check the ground connection from the fuel tank sender to the frame.

If this ground wire is broken or is loose/corroded at the frame bolt or sender tab there is no path to ground for the "E" side electromagnet in the gauge. Consequently the electromagnet that drives the "F" side will be stronger and pull the needle to it's pegged high position.

My money would be a bad sender to frame ground wire - happens all the time as these trucks turn 30 years old. The fuel gauges on the other hand rarely fail in comparison.

There will be a short black (or blue) wire that connects the sender head to the frame. At least look at it before buying a new gauge and tearing the instrument panel apart.

Always check the simplest and cheapest stuff first.

We scrapped off the rust and paint and re-ground that wire while the bed was off. But, will look at it again.

 

[Qwk]

Crap! Ground is good. We even hung a new sender, plugged it in, grounded it, turned key on....NOTHING. Needle still at 3 oclock position.

 

[Qwk]

It was the SENDER!!!

 

[chengny]

I'm telling you, with aftermarket parts, it's getting harder and harder to troubleshoot these days.

You just can't assume anything.

Used to be - if you were troubleshooting a system and had recently replaced an associated part, you could check that part off and move on to the next step. Not anymore.