Hello All

My first post and first question is on a wiring issue im having on my 89 ford elite motorhome (E350). It has the FI460, C6, New 63 gal fuel tank (replacement of the old 33 gal). When i first installed the fuel tank ( which utilizes the factory fuel pump and level indication) everything worked just fine. Then a month later after a long trip the fuel gauge stopped working. A voltage check confirmed which wires were which (only has 3-black/orange / yellow) in the wiring harness connected to the fuel pump and level float. I havent done a ohms resis check yet because the fuel tank is still full. But when i did check the yellow wire for voltage it had voltage fluctuations like a turn signal. the OJ wire had constant voltage for ~5 secs till the fuel pump relay cut out.
Has anyone ever had this problem before ? Or can anyone please help im confused.
Thanks

 

The voltage fluctuating sounds right for the one wire. This voltage comes from the instrument cluster voltage regulator. It sounds like your sending unit is bad.

 

The orange wire = power to the fuel pump.
The black wire should be ground.
The yellow wire goes to the sender.
Ground the yellow wire and temporarily turn the key on and watch the gauge. If it goes to "Full" (or even past), the problem is definitely in the sender (or its ground). Don't leave the key on too long to keep from burning out the gauge.

The pulsing voltage to the sender is normal.

 

Thanks for the info I'll try those fixes

 

Thanks for the tips I checked the yellow wire to ground and the fuel level guage worked so it's the sending unit it appears. I also checked the ground wire and hooked up a temp ground wire to ensure that it wasnt a bad ground.
Now another problem it appears that the fuel pump and sending unit are on the same unit so in order to replace the sending unit i have to replace the fuel pump also ford wants $462 but it seems kind of a waste since theres nothing wrong with the fuel pump. Is there any fix I can do to the sending unit w/o changing out the entire assembly ?

 

I've yet to replace mine but I was under the impression that you can buy the sending unit itself. It's still expensive. I'm looking at Advanced Auto's website and it shows American Designers F15D for $99.88.

 

Thanks for the info I'll research further into it then.