Gas gauge pinned at full

[Ranger8867]

Hello I’ve got an 88 ranger 2.9 and I’ve just started haveing this issue today but in the morning my gas gauge was working but in an hour all of sudden look down and it’s pinned at full even though I was at half last time i looked turned the truck off let the gauge go all the way back down tried again and still went all the way up. “ note it’s got a new fuel pump sender only about 3 month old” but traced the yellow wire as best I could from the tank all the way and it looked fine check resistance and said 22.1 when I check what’s going on?

 

[franklin2]

Sounds like something is loose or open. If you can reach it, you can go back and unplug the sending unit/pump wiring plug. The gauge should be pegged like it was since the sending unit disconnected. You can then ground the yellow/white wire with a jumper, and then the gauge should go all the way pegged to empty. If it passes this test, the wiring and the gauge are working, you must have a loose connection at the sending unit or the sending unit is bad. Won't be the first time, especially lately, that a new part is no good.

 

[Ranger8867]

Ok wasn’t able to get to trying what you said oregon coast is going through a bad ice storm but yesterday went and filled it with the gauge still not working took 11 gallon but running it around that day magically the gauge worked but going out to start my truck today to warm it up because it was 29 degrees it’s now pegged all the way up agin

 

[RonD]

Pre-1989 Fords used these OHMs for sender and gauge
..E.....F
73-10 Ohms

0 ohms is a short to ground so would read above FULL
No connection/high ohms would read below EMPTY

So there could be a short to ground on that yellow wire

 

[franklin2]

Pre-1989 Fords used these OHMs for sender and gauge
..E.....F
73-10 Ohms

0 ohms is a short to ground so would read above FULL
No connection/high ohms would read below EMPTY

So there could be a short to ground on that yellow wire

I wondered if the rangers went farther with the older style sending units. I guess this is proof they did.

eClassics 1986-1988 Ford Ranger Solid State Instrument Cluster Voltage Regulator

Buy this Voltage Regulator for 1986 Ford Ranger, 1987 Ford Ranger, 1988 Ford Ranger

eclassics.com

The larger trucks stopped using the older system after 1986.

Here's proof of that.

eClassics 1980-1986 Ford F-250 Pickup Truck Solid State Instrument Cluster Voltage Regulator

Buy this Voltage Regulator for 1980 Ford F-250 Pickup Truck, 1981 Ford F-250 Pickup Truck, 1982 Ford F-250 Pickup Truck, 1983 Ford F-250 Pickup Truck, 1984 Ford F-250 Pickup Truck, 1985 Ford F-250 Pickup Truck, 1986 Ford F-250 Pickup Truck

eclassics.com

 

[Ranger8867]

Finally had to day to go through the wiring for the signal wire found it was chafing just a tad at just the right angle and causeing it to pin got it fixed and no problems