1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Fuel gauge, Clock broken

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Old Mar 24, 2016 | 04:02 PM
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Fuel gauge, Clock broken

Hi All,

The fuel gauge on my 79 does not work and the clock is also broken. I believe that the mechanic who did some initial work on my car told me that he tested the actual fuel sensor with an ohm meter and it was working. If this is the case, then could there be a short somewhere in the dash. Perhaps a common thread with the clock that doesn't work?

I also notice that periodically while driving that the tach goes up to 8000 and some warning lights come on only for a few seconds. There is no interruption of engine power when this occurs. It's like when you first start the car and it's in voltmeter mode.

Any ideas about HOW I should proceed to fix these problems? The fuel gauge is the big one to me.
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Old Mar 26, 2016 | 02:51 AM
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Originally Posted by Coochas
Hi All,

The fuel gauge on my 79 does not work and the clock is also broken. I believe that the mechanic who did some initial work on my car told me that he tested the actual fuel sensor with an ohm meter and it was working. If this is the case, then could there be a short somewhere in the dash. Perhaps a common thread with the clock that doesn't work?

I also notice that periodically while driving that the tach goes up to 8000 and some warning lights come on only for a few seconds. There is no interruption of engine power when this occurs. It's like when you first start the car and it's in voltmeter mode.

Any ideas about HOW I should proceed to fix these problems? The fuel gauge is the big one to me.
Fuel gauge should be fairly simple. Get a wiring diagram from a shop manual or online and do some wire chasing. Amazed the sender is good, they normally go bad. SA senders are NLA and the FB sender fits but has a different impedance.

SA clocks go bad. Buy a cluster and swap it or try to fix it. A clock is a clock and someone with knowledge could possibly repair one.

The tach issue reminds me of a problem I used to have on my SA. Do you still have the stock points ignition? If so, if the points are misadjusted it can cause the tach to read high intermittently. At least that's my experience. Swap to a FB distributor with some version of direct fire and enjoy. Could also be a problem with the alternator circuit. What warning light is lighting up? If its the "gen" light it is the alternator itself or associated wiring.
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Old Mar 26, 2016 | 03:55 AM
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IIRC there is actually an electronic box on the BACK of the cluster that controls the power to the clock. I know one forum member here traced the fault to THAT (after going to a lot of trouble to disassemble the cluster and exchange the clock itself). As suggested, getting a used cluster to even swap in _entirely_ might be a good way to see what is the problem. And either way you will have some spare parts. These sell on ebay for under $50 quite often.
And dead-easy to swap too BTW.

Stu Aull
80GS
Alaska
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Old Mar 26, 2016 | 09:00 AM
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Originally Posted by Joe428
Fuel gauge should be fairly simple. Get a wiring diagram from a shop manual or online and do some wire chasing. Amazed the sender is good, they normally go bad. SA senders are NLA and the FB sender fits but has a different impedance.

SA clocks go bad. Buy a cluster and swap it or try to fix it. A clock is a clock and someone with knowledge could possibly repair one.

The tach issue reminds me of a problem I used to have on my SA. Do you still have the stock points ignition? If so, if the points are misadjusted it can cause the tach to read high intermittently. At least that's my experience. Swap to a FB distributor with some version of direct fire and enjoy. Could also be a problem with the alternator circuit. What warning light is lighting up? If its the "gen" light it is the alternator itself or associated wiring.
Thank you.
I will check the fuel sensor myself just to be sure. I have a FSM and will start to chase where the problem is.
I didn't realize that entire instrument clusters were available for reasonable money. I'l;l keep my eye out for a nice condition 79.
With the tach issue, it is at least three lights going on at the same time. I'll try to snap a pic of it when it happens. It just doesn't happen all the time. The battery is holding its charge well so I'm hopeful that it is not the alternator.
The distributor/points are the stock SA set up.

Originally Posted by 7aull
IIRC there is actually an electronic box on the BACK of the cluster that controls the power to the clock. I know one forum member here traced the fault to THAT (after going to a lot of trouble to disassemble the cluster and exchange the clock itself). As suggested, getting a used cluster to even swap in _entirely_ might be a good way to see what is the problem. And either way you will have some spare parts. These sell on ebay for under $50 quite often.
And dead-easy to swap too BTW.

Stu Aull
80GS
Alaska
Thanks Stu. I'll look around.

I'm just so happy that I got this car running again!!! I believe today will be a Saturday cruise day.
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Old Mar 26, 2016 | 02:29 PM
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I confirmed while driving today that the tach pegs at 8000 while the oil, coolant and generator lights all come on. There is no change in engine power during this. It seems to be associated with bumps but usually doesn't occur.
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Old Mar 27, 2016 | 04:33 AM
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Pull the cluster and check the wires
Pics here might help-
Note silver box on back in one pic: THAT is the clock's electronic controller...

Stu Aull
80GS
Alaska
Attached Thumbnails Fuel gauge, Clock  broken-speedoremove.jpg   Fuel gauge, Clock  broken-rx-facia-clip-2-sm.jpg  
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Old Mar 27, 2016 | 06:36 AM
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Doesn't the check and choke relay control all of that? I would disconnect it and see how it acts.
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