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Jaf · Joined: 08 Jun 2006 Posts: 194 Location: Oria. Spain

My fuel guage reads as full so I'm trying to understand how the system works. Haynes says that if the guage reads full it's the sender or the guage. I'm confused as to how the guage can fail and so show full? I have tested the sender with the readings in Haynes and it seems fine. I would take the guage out but it's being stubborn, despite a few taps with a hammer, and I don't want to force it, especially if it could be a loose wire or dodgy earth instead of the guage. Fortunately my odometer works so I've been using that to know when to go get fuel.

Anyone walk me through how it works?

Thanks,

Jaf
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1978 924na

Lizard · Posted: Thu Sep 21, 2006 6:25 am Post subject:

it works by resistance, and a piece which floats rubbing on two piece of small wire, 1 wire straight to ground, 1 to the guage, as the float goes down there is more wire for the current to travel through and more resistance = less voltage going through.

hope that is simple enough
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3 928s,

Vince Ponz · Joined: 02 Nov 2002 Posts: 3581 Location: Florida

If you plan to clean it do I would be careful not to stretch the wires. The only thing you can do is soak it. It probably it gunged up. You can open it via the fiber nut on the bottom. Then soak it and put it back. The wires are very thin and stretch easily. Do stretch them and you are looking at a new sender or about $40.
Good luck.
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"Never let them see you sweat"
77.5 924 modified track car
79 931 Euro stock
88 924S SE
87 911 Targa stock

Paul · Posted: Thu Sep 21, 2006 9:05 am Post subject:

The gauge reads full if you short it's wire from the sender to ground....

Does the gauge read empty when you pull the wire off the sender?
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White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

924RACR · Posted: Thu Sep 21, 2006 9:51 pm Post subject:

Hey, look what I found!!!
http://www.924.org/techsection/gas_sender.htm
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

Vince Ponz · Joined: 02 Nov 2002 Posts: 3581 Location: Florida

I read the article and do not entirely agree. If you have to clean the wires use a very soft brush. The second omission is to disconnect the battery.

I went through this cleaning and wiped the wires and they stretched. I bought a new one.

You have nothing to lose cleaning the sender. If you fail you will buy a new one anyway.
_________________
"Never let them see you sweat"
77.5 924 modified track car
79 931 Euro stock
88 924S SE
87 911 Targa stock