Gauge, senders, or TSV?

[F350farmboy]

The fuel gauge doesn't work in the '89 on either tank. The gauge pegs full until the tank gets pretty low (but no idea how low....low enough that I run it dry if I ignore it too long), then it will rock to about a half, then go full tilt "full" within 15-20 miles.

I only run on the rear tank because the TSV is bad and wont switch tanks, but the gauge will still read full when I know its bone dry.

So is there a test to see if the gauge is bad? I have a cluster from a '89 F-250 460...will the fuel gauge swap between the two clusters?

Thanks alot guys!

 

[franklin2]

Find the gauge sending unit wire back at the tank. Unplug it, and with the key in run but the engine off, ground the wire. The fuel gauge should swing full scale full or empty. Then take the wire off ground and let it hang in the air and touch nothing. The gauge should swing full scale the opposite direction. If it passes this test, the gauge, the wiring, are working ok.

Going by memory, I believe the gauge wire at the tank is a blue/yellow or a yellow/blue.

 

[f-two-fiddy]

I'd put My money on a bad sender

 

[Jake S.]

When the resistor board on the sender goes bad, they peg full.

 

[subliminal]

its usually when the contacts on the arm rub through the contacts to the circuit board on the rheostat. i have bent the contacts to contact a different area on the board so they werent rubbing on the worn out part and it seemed to work well for quite a while. you could also just replace the sender. if it was anything other than the contacts it would always read slap full but since you are getting readings at near empty id bet on the worn/dirty contacts being the problem

 

[F350farmboy]

I was afraid of the senders being bad...that probably means both front and rear senders are bad. I've heard alot about JC whittney's universal senders, but what are the advantages of them...cheaper?

I was hoping it was the gauge, oh well.

 

[F350farmboy]

Well the gauge checked out ok. So how should I go about the senders . Should I go stock replacement, or get a separate aftermarket sending unit like something along these lines? sunpro 240/33 ohm sender

Thats the one on that J.C Whitney sells as well and autozone has an autometer one for less than $40

And if the FSV is bad, would the gauge still work with working senders?

Thanks

 

[Jake S.]

80-86 and vans till ? = 10 ohm full, 70 empty
87-up = 160 ohm full, 15 empty
The gauge switch is the last part to switch in the FSV. Generally if the gauge switches tanks, fuel does too.

 

[F350farmboy]

I always thought it was 240/33....
Should I just bite the bullet and buiy dealership senders?

I might end up getting 2 fuel gauges, one for each tank and bypass the FSV with 2 manual valves like midnightrider suggested.

 

[f-two-fiddy]

Good luck with the stealership, NLA.

Gonna have to go after market. There was a thread here that explained all of the gory details of using a fairly inexpensive JC Whitney sender.

 

[F350farmboy]

I found out the selector valve works, the hard way. I must have switched it to the front tank by accident when I had the dash apart switching gauges. The gauge still read way over full but I was going down the road and it died on me....

I ordered 2 of those sending units and I'm hoping for the best.