Well, my new (3 or 4 years) factory fuel sending unit has gone bad. Yesterday it dropped to empty when I still had half a tank left. I don't want to pay 103 bucks for a new one. I checked the resistance on the one still in the tank, and it's not horribly off. The gauge reads empty cause the resistance the sender is sending is for empty.

Can these things get stuck in the empty position? I've tried driving over some good dips at about 35 to try to jar things loose, but no dice. Float fall off maybe?

Any ideas are appreciated.

I just replaced mine. The float is attached to an arm that pivots about a point. The arm then wipes across a variable resister so the resistance changes as the arm and float move. Based on this and the ease that my arm moved, I doubt the float is stuck. It would take a lot to do that.

So the problem with mine is that the resister contact was worn through, specifically at the 3/4 mark. As soon as my tank went down to 3/4, the gauge would act all screwy.

Here's a picture:


The resister is in my right hand and the float is all the way down so that would be empty. I don't think there's an easy way to fix it. Your best bet is to replace it.

Darn, there's a hundred bucks gone <img src="/forums/images/graemlins/frown.gif" alt="" />

The weird thing is it's sending the empty signal... Wouldn't it have no resistance at all (open) if the wire were worn through? Is there any way the float could have fallen off?

TAP sells them for about $35 shipped to your door.

I would think an oem one should last a lot longer than 4 yrs.

Read this before buying at tap, then make your own decision...

http://www.pirate4x4.com/forum/showthread.php?t=2424&highlight=tap

You got your terminology mixed up, an "open" is infinite resistance. If I remember correctly empty is higher resistance and full is lower resistance so the symptoms make sense. An open should show infinite resistance, thus the empty signal.

Yeah, my terminology is rudimentary at best.

So infinite resistance would be probes not touching on the multimeter? And zero (or very close to) would be just touching the probes directly to each other?

The reason I'm wondering is this:

The FSM lists resistance for 'full' as about 3 ohms, and 'empty' as 110 ohms. To me, if it did break somewhere along the wire, there would be infinite resistance because current couldn't flow over the circuit, correct?

When I hook the probes across the pins, I get about 110 ohms, which is the empty signal, which says to me the wire isn't broken, the arm is just sitting at empty. Either stuck or missing the float.

Does that make any sense or should I just stop trying to comprehend electricity? <img src="/forums/images/graemlins/lol.gif" alt="" />

Have you tried putting more gas back in? If the gauge suddently starts reading again, then it's probably not a float issue. I would also agree that it takes virtually nothing to move the float/arm assembly, so it is unlikely that is has siezed up somehow. But.... is the inside of your tank rusty? Perhaps the sending unit rusted or something built up on the resistors. Also, it could always be the actual gauge itself. I think filling the tank back to full, checking to see if the needle shows gas again, and then re-checking resistence at the sending unit would give you a better idea what's going on.

i had the same problem on my bikeand it turn out to be a loose connection at the fuel pump have you looked at the connection to the fuel pump i know a lot of moisture likes to hang out there

Remember to inspect your wiring, as this IS an older Toy. Things start getting brittle and failing. My Ol' Blue has a few soldered areas and heat shrink now.