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jgolfer · Joined: 12 Feb 2004 Posts: 47

My gauge will only get to 3/4 full mark after a fillup. When the tank is low, it is very unreliable, it just stays somewhere around a 1/4 tank and may occasionally drift behind "empty" on turns, any suggestions my friends.
Peace
J

CMXXXI · Joined: 05 Nov 2002 Posts: 1939 Location: Vicksburg, MS

I think about all you can do is get a new sending unit. While the units can be refurbished, the internals are pretty delicate. If memory serves me right, the float in the thing is a formed "block" of high density foam/plastic, and it isn't hollow. So, if it always registering low, it sounds like the float is saturated, or (more likely) the wiring has extra/excessive resistance causing it to register low.

Fuel enters the tube of the sending unit through a small hole in the bottom plate that has a spiral pattern cast in it. This causes the filling and draining of the tube to happen "relatively" slowly so you don't get "wild" gyrations of the indicated fuel level. If it is indicating any movement as you fill the tank and shows a decrease as you use fuel, the hole can't be plugged.

(Might want to move this post to the "General" area where more folks may see and comment)
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'79 Eurospec 931

924RACR · Posted: Sat Mar 06, 2004 4:06 am Post subject:

Very common problem - resistance in the wiring. You may have success cleaning off the external contacts on the top of the sender; you may have to pull it out, disassemble, and clean the internal wiring.

I have cleaned off the external contacts on mine, it still reads low, so now I have to go and clean out the insides...

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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

Smoothie · Posted: Sat Mar 06, 2004 4:38 am Post subject:

I tried both of those with no luck, but some report good results, so they're worth the try. I rely on the still-accurate low fuel warning light. Whenever that comes on I steer myself directly to a fillup. (Then I put only 10 gallons in to prevent the fuel vapor smell inside the car.

)
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Joes924Racer · Posted: Sat Mar 06, 2004 7:25 am Post subject:

You cant rely on that light guage though if you like to drive im sure you like to drive...I cleaned mine up and it appears it should be worken I have to test it ... it quite worken I did the rebuild clean up on the sender to no avail somethings still wrong. I have no guage right now though I have a stand by yellow faced guage to try then if it dont work its a power prob. . Im really close to buyen a seperate guage This is really tiren I need to have a guage I like to know how much is in there.
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

numbbers · Posted: Sat Mar 06, 2004 11:06 am Post subject:

I had the same problem with mine when I bought it. I removed the sender from the tank via the port under the carpet in the rear hatch area. I took the innards out of the sender and cleaned the slider and the wound wire with crocus (polishing) cloth, and bent the slider a little for better contact. It still works 19 years later.
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1980 924 Turbo

jgolfer · Joined: 12 Feb 2004 Posts: 47

Thanks fellas, I will clean the sending unit and see if it helps. I has duct tape over it, it seems to have been addressed sometime in the past, I will let you know what happens.
Peace
J