Oil & Fuel Fixing fuel gauge (on a 3930)

[charlesw]

So... Yeah. Fuel gauge doesn't work. First, I suppose, I need to figure out what is causing the problem. Then I need to fix it (duh!). Maybe first I need to buy the repair manual. But, shucks, it's $220 for the real one (plus $34 for the Intertec). Heck, after paying for the tractor I've got nothing left to give!

'Course, you could say that I've got a big tank and I should just deal with it for now. Like, using a stick to figure out how much is left in the tank. Um. Kind of like I'm doing now! I suppose this works. And, as I said, it does have a big tank. But you've got to know that at some point it will probably run dry - 'cause I just don't know!

I suppose that the best solution for now is just paying attention. Any other clever ideas?

thx,
charles

 

[RickB]

If the gauge reads empty all the time; You have a plastic tank so the first thing I would check is the ground path from the sender to the tractor chassis. Next, check for voltage at the sender with the key 'ON'. If voltage is present, momentarily ground the lead showing voltage and observe the gauge. It should immediatly go to 'Full' if the gauge and sender wiring are good and the sender or its float has failed. If the gauge reads full all the time, the gauge has failed, the sender wiring is shorted to ground, or the sender is internally shorted to ground which would be the first time I ever heard of that. Run through this list and post back if you need more. Does the temp gauge work?

 

[charlesw]

Ok, good things to check, Rick. I'll do so sometime this week. For what it's worth, the gauge always shows empty and the temp gauge works fine...

 

[charlesw]

So... I filled the tank (for the first time). The gauge works! Sort of! It shows 3/4 of a tank... So, yeah, I've got a few random guesses:
- breached or, more likely, bent float
- a shorted wire somewhere.

Of course, I should be able to visually inspect for obvious signs for the latter. I guess I'll get on that!

 

[charlesw]

Shucks, I wrote an update and it vanished into the aether... Anyway, I filled the tank (for the first time) and found that the gauge sort of works. It shows 3/4 tank when full. So, now I need to check for shorts in the wires and condition of the floater, I imagine.

 

[RickB]

A short is unlikely. An incomplete ground path from the sender is most likely. A "breached float" is not likely at all. Not that floats can't fail, but they rarely fail and retain enough bouyancy to show 3/4 of a tank when the tank is full.