Sending unit/fuel gauge question

[thewestwon]

I recently extended my 25 gallon tbi sending unit on my '87 to fit my new 31 gallon tank. The pump is operating properly and the gauge was reading correctly when i first got it hooked up. Today, though, while driving down the interstate, the gas gauge went about 3 inches above full (the same thing it does when the sending unit is not hooked up) and stayed there. Since the pump still works fine, I'm going to assume the problem is not with the wiring on the sending unit. I've played around with the ground wire outside the tank with no luck. Does anybody have any ideas on potential fixes? I might also be noted that the only gauge that is not working is the fuel; everything else works fine.

 

[toomany]

The sending unit can go bad and the pump still be working.

All the fuel level sending unit is, is a resistor. The height of the float changes the resistance and the gauge.

 

[thewestwon]

alright. to me that idea seemed unlikely, though, since the pump is down in the tank and the wiring to the pump and the sending unit is connected in the harness. i was afraid that was going to happen, though. the 31 gallon sending unit for an 87 is 349.95 from classic parts .

 

[fallout232]

You might try Rockauto, Everyone wanted 250-300.00 for my diesel sending unit for a 40 gallon tank. I found mine on rockauto for 80.00 after shipping it was like 95.00. Off brand but still going strong a year later

 

[dyeager535]

Seen them at places like JCwhitney or gastanks.com for $75.

For instance: http://www.quantaproducts.com/prodinfo.asp?number=SUFG12K

Or, wrecking yards will probably sell whole tanks for $40, but who knows what you are getting. Might get a new pump and good sender, or junk. And your effort.

Fail. This is the 31 http://www.quantaproducts.com/prodinfo.asp?number=SUFG12L quite a bit more.

 

[thewestwon]

i actually bit the bullet and bought one earlier from rockauto for 103 including shipping, which is considerably better than classic parts' 350. I already had a brand new 31 gallon tank or the junk yard probably would have been my first stop.