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temp and fuel gauge

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temp and fuel gauge
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Rescuejeff

Jeeper
Posts
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Location
Greater San Diego Area
Vehicle(s)
1983 CJ7 Laredo, 258 inline 6 with stock everything else. Have a Dana 300 trans with and Dana 30 front axel and AMC 20 wide trac rear end with a T-5 tranny.
Did the nutter bypass and took off the cat.
I have been putting my 83 CJ7 back together and now dealing with a issue of the temp and fuel gauges not working. The temp did not work when I bought it...it always read hot. The fuel gauge barely worked. I bought new gauges and some how I burned up the fuel gauge and the temp gauge pegged every time. SO I bought a new complete cluster with speedo. Turns out even when I hooked up the new one it does the same thing....Need some help with this. Thanks in advance.:chug:
 
Rescuejeff said:
I have been putting my 83 CJ7 back together and now dealing with a issue of the temp and fuel gauges not working. The temp did not work when I bought it...it always read hot. The fuel gauge barely worked. I bought new gauges and some how I burned up the fuel gauge and the temp gauge pegged every time. SO I bought a new complete cluster with speedo. Turns out even when I hooked up the new one it does the same thing....Need some help with this. Thanks in advance.:chug:
Click to expand...

I've got the same problem. My temp gauge kinda works (not sure how accurate), but i'm getting nothing from the fuel gauge. I also thought about changing out the speedo cluster. Looks like it was a good thing I didn't!

Good luck with finding some answers. I know I could use 'em! :)
 
Be advised, on some wiring diagrams I have seen/ used the wire color for the fuel and the temp are reversed. I think it has something to do with the diagram being the back of the gage. Do follow the wires to confirm that the fuel sending unit goes to the fuel gage etc. I have always thought that if the gage responds to voltage it works so at 12V the gage, whatever it is, should be pegged. I would suggest the problem is in the sending unit rather than the gage.:D
 
It's probably covered in the trouble shooters guide, but it never hurts to repeat. The power sending unit, which is in one of the gauges, sends a pulsing signal to the gauges. This prevents the gauge from bouncing all over the place responding to the change infuel levels on a bumpy road.

I changed both my Volt meter and oil pressure gauges over to Auto Meter gauges. I like'em a lot and they are far better than the replacement Jeep gauges.
 
Hedgehog said:
It's probably covered in the trouble shooters guide, but it never hurts to repeat. The power sending unit, which is in one of the gauges, sends a pulsing signal to the gauges. This prevents the gauge from bouncing all over the place responding to the change infuel levels on a bumpy road.

I changed both my Volt meter and oil pressure gauges over to Auto Meter gauges. I like'em a lot and they are far better than the replacement Jeep gauges.
Click to expand...


so, thats why one side is tied together? :cool:
 
Exactly. I keep talking about this fella, but he has tought me a ton of stuff about how a jeep works. Rob says that he has quite a few customers that burn their gauges out by sending power to the wrong posts. The gauges need power to one post, the gauge "Shapes" or transformes the output power which feeds into the gauge itself AND the other gauge through the jumper. Bypass the jumper, burn out your gauges.
 
Trying to figure out mine as well. A little confused. Do both the temp and fuel gauge have to be operable in order to work due to the jumper?
 
Not so much the gauge itself, but deffinately the transformer needs to work.
 
Neuner said:
Trying to figure out mine as well. A little confused. Do both the temp and fuel gauge have to be operable in order to work due to the jumper?
Click to expand...

Neuner, I've worried over no-read fuel and temp, read everything ever written, torn open the dash and into the instrument cluster, checked off each line in the trouble-shooting guide by John Schrenk and I still have no gages.

The main two things pounded into your head by all the guides are GROUNDING and SENDING UNIT. I had a badly-rusted tank that is now a new poly-plastic unit with a new sending unit, tested before the tank was bolted up. Eliminate that. I built a grounding buss system with 2 gage multicore wire, copper piping, copper connecting bolts and silver soldered wire joints. Eliminate that.

I am about to tear into it again in conjunction with a tilt-steering rebuild. If I make any discoveries at all, I'll post 'em here for you and all to see. That includes me when I have to repair the gages again.

Here are views of the grounding system, front and over the rear axle, that I fabricated.
 
What keeps the copper pipe from crushing.
 
Ok...so checked all the grounds and added the ground to the tub off the negative of the battery. Did all of that and still having an issue with the temp gauge pegging to hot. The replacement cluster is slightly different in then the old one. There was just two post on each gauges...temp and fuel. These are different in that the fuel has three post on it. Looking at the web it talks about the resistor strap...there is not one on the cluster. Would that change in voltage cause the sensor to peg the temp??? Thanks for everyones help!
 
Hedgehog said:
What keeps the copper pipe from crushing.
Click to expand...

Hedgehog, it is just good pipe. I crank down smartly on the stud nuts, and after over a year, not even one has loosened up. I'm sold on the idea. I have dropped the word "grounding" from my Jeep vocabulary (but have taught my lovely wife a few new Jeep words as she was watching me work).
 
What I have found out about the gauge is that it grounds through the speedo housing, If it doesnt have a good ground it will burn up the gauge in a matter of seconds..
 
The wire in the gauges is hair thin and will burn in a hurry.
 
:ww::dbanana::banana:

Rescuejeff hasn't been on since 6/2/16.

LG
 
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