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Unread 09-24-2008, 11:53 AM   #1
martyweir
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1976 CJ7 
 
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Tank is full, fuel gauge reads Half tank!?!

I have stock dash cluster, and the fuel gauge is reading half full when tank is full (just filled her up for first time in several years).
I put in new temp gauge / fuel gauge about 3 years ago before storage. New Fuel sending unit at same time, and I'm pretty sure it worked then.

Any help on where to start here???

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Unread 09-24-2008, 12:11 PM   #2
aero mech
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Has it ever been acurate. I replaced mine and had to calibrate it by bending the float arm. You can also bend the stops. I ended up with 2 gallons left on empty and the had barely goes to full. Good luck. jc
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Unread 09-24-2008, 12:11 PM   #3
whittlecj
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http://www.jeepforum.com/forum/f8/fuel-guage-doesnt-work-607785/

I was going to recommend John Strenk's web pages but they seem to be down. If he needs a host I will provide if I can, they are too good to go missing from the net.
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Unread 09-24-2008, 12:43 PM   #4
martyweir
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Thanks for the help aero. I may consider this, Will have tub off soon... WittleCJ, I read all of those, and didn't come across anything with guage working, but giving incorrect reading. Might be callibration issue / or voltage issue from gauge.

Anyone else ever have an issue w/ this?
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Unread 09-24-2008, 01:19 PM   #5
Mike Romain
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I would be checking the ohms from the sender on the pink wire.

The gauge 'can' be calibrated from behind. It has a range and top/bottom adjusting slot in the stock gauge.

Here is one page on the gauge diagnostics:

http://jeep.off-road.com/jeep/articl....jsp?id=261534
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Unread 09-24-2008, 01:48 PM   #6
aero mech
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Quote:
Originally Posted by Mike Romain View Post
I would be checking the ohms from the sender on the pink wire.

The gauge 'can' be calibrated from behind. It has a range and top/bottom adjusting slot in the stock gauge.

Here is one page on the gauge diagnostics:

http://jeep.off-road.com/jeep/articl....jsp?id=261534
Mike can you go into little more detail. I wasn't aware of this I am going to change my sending unit out soon beings it worked for two tanks of gas and now inop. You just can't find good replacement parts jc
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Unread 09-24-2008, 03:13 PM   #7
Fjguercio
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Dear Aero,

Take a look at the link in Mike Romains post... very good article and lists the resistance levels for the sensors so they can be checked out.

An example.
My CJ7 reads low on temp guage even when hot and going down the road. Using this write up link tested the cold reading and the Thermister is reading 47 ohm cold vs 73 ohms so close and will ck when hot and should be close to 9 ohms. If it is does not ohm out hot, I may need a new sensor.

Similar values were posted for the fuel tank and oil pressure systems.

Nice article, I printed it, Thanks Mike,
Fred
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Unread 09-25-2008, 03:47 AM   #8
John Strenk
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Maybe the float on the sending unit is filled with fuel and wont float anymore. Many guys go with a brass float now.

I'll see what's up with my web site.
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Unread 09-25-2008, 03:56 AM   #9
John Strenk
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Ahh
Here we go...

http://home.roadrunner.com/~john.str...for_cj_gau.htm
http://home.roadrunner.com/~john.str...QuickFacts.htm
http://home.roadrunner.com/~john.str...eQuickTest.htm

http://home.roadrunner.com/~john.str...ageGauges1.htm

Still, maybe I need an alternate site to host them. Just in case. i was pretty jittery when I realized I might not have a backup to restore the pages.
whittlecj, you still offering some room?
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Unread 09-25-2008, 06:36 AM   #10
whittlecj
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Quote:
Originally Posted by John Strenk View Post

Still, maybe I need an alternate site to host them. Just in case. i was pretty jittery when I realized I might not have a backup to restore the pages.
whittlecj, you still offering some room?
Sure, PM sent.
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Unread 09-25-2008, 06:55 AM   #11
aero mech
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Quote:
Originally Posted by Fjguercio View Post
Dear Aero,

Take a look at the link in Mike Romains post... very good article and lists the resistance levels for the sensors so they can be checked out.

An example.
My CJ7 reads low on temp guage even when hot and going down the road. Using this write up link tested the cold reading and the Thermister is reading 47 ohm cold vs 73 ohms so close and will ck when hot and should be close to 9 ohms. If it is does not ohm out hot, I may need a new sensor.

Similar values were posted for the fuel tank and oil pressure systems.

Nice article, I printed it, Thanks Mike,
Fred
Fred, Thanks for the tip. I understand about the omhs part. I tested mine before installing it and also filled the fuel tanks and checked it that way. I was actually refering to the adjustment on the gauge. I'll check the sight links posted up. Thanks again jc
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