AudiSport4000

I posted a week or so ago about a strange ordeal at the gas station with my 85 4k. If you recall, I thought I filled up, but it only read 9 gallons had been put in, and the tank was nearly empty, so the gauge said.
Get in the car, gauge reads a bit below half, wtf. I go back and try and put gas in the car, it more or less comes out, soaking my shoes. Im confused at that point, and end up getting a dollars worth of gas in. Gas gauge still the same, obviously.
Tonight comes, and I had to make a late night dash, so I took the trusty ol 4k. Gas gauge still read the same, but at some point in my trip, I look down, and the gas gaugue needle is near the top (full mark).
Whats going on, is there a problem with the tank sender? Any thoughts? Any way to test it?
TIA

Mike

NikonF3T

Is gauge sending unit mechanical or electrical? Checked the service manual and I can't figure out which. Since there is no float, we can rule out the float being bad.

Maybe it was stuck for some reason for a while and was unstuck for some reason and started working again?? Hmmmm...

AudiSport4000

When I filled up, it shoulda put alot more than just 9 gallons of gas in, thats what gets me.
Who knows, Im gonna monitor this silly gauge.

Mike

Whitjr

Worth checking the connections in there. Maybe they are loose.

M0W0G

Iy could be the voltage stabilizer that's built into the dashboard. It supplies +10vdc to the fuel guage and the coolant temp gauge. If you notice both gauges are low then it's a possiblity. Bently has a test procedure but it sounds like your problem is intermittant so it might be hard to verify.

Llyn

85-4kq-girl

My gauge did something similar to yours when we were doing the fuel pump, accumulator, filter, check valve, etc fixes. When it was done, I didn't put the cover back on the fuse box (oops!) and left it outside over night. Then I immediately noticed it floating around at the half way mark but I KNEW it was full. Then I realized the cover wasn't on and I suspected some moisture got down in there. It could've been really ugly. I put it back on, and a week or so later, it magically started working perfectly. Soooo...moral of my ramblings: check your fuse box because that was my culprit.

Now go reserve a damn hotel room for Carlisle or you'll be camping with AudiTrippin!! And if camping is what you want, you have to register for it and I think it's $15 per night.

--morgan

gmbchef

The gauge should move rapidly to full. If it does, then yank the sending unit out of the tank, replug it in, and move it throughout its range and see what the gauge does. If that works then the small 3 pronged regulator on the PC board behind the instrument cluster may be shot.
HTH

JeromeS.

Its most likley the fuel tank sending unit. Those usually fail before any guage.