Fuel Gauge Erratic |
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John Cotner
Member Joined: 11 Sep. 2014 Location: New Ulm, MN Status: Offline Points: 355 |
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Posted: 30 July 2021 at 6:15am |
I just replaced the fuel gauge and sender on my '46 CJ2a. I tested the sender unit ut of the tank and all works well. When I turn on the key the gauge reads accurately. When I start the engine the fuel gauge reads accurately at idle, but when I apply power it goes to full no matter how much fuel is in the tank. When I stop at a light and the motor goes back to idle the gauge reads accurately again. This is more a minor inconvenience than a serious problem since I don't drive long distances, but I want to make sure there isn't some larger electrical problem lurking.
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Thanks,
John Cotner New Ulm, Minnesota |
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TERRY
Member Sponsor Member Joined: 22 May 2007 Location: BOULDER COLORADO Status: Offline Points: 3400 |
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What voltage gauge did you get?
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BOULDER 48 2A
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John Cotner
Member Joined: 11 Sep. 2014 Location: New Ulm, MN Status: Offline Points: 355 |
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Six volt. I have a six volt system.
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Thanks,
John Cotner New Ulm, Minnesota |
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TERRY
Member Sponsor Member Joined: 22 May 2007 Location: BOULDER COLORADO Status: Offline Points: 3400 |
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Chech the voltage output, sounds like the charging system is at fault.
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BOULDER 48 2A
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John Cotner
Member Joined: 11 Sep. 2014 Location: New Ulm, MN Status: Offline Points: 355 |
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Where is the best point to check? The generator is a somewhat recent rebuild from the PO. The regulator doesn't look original but is pretty old.
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John Cotner New Ulm, Minnesota |
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DMusil
Member Joined: 23 Apr. 2019 Location: Wisconsin Status: Offline Points: 271 |
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Hook a meter up to the battery.
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DMusil
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John Cotner
Member Joined: 11 Sep. 2014 Location: New Ulm, MN Status: Offline Points: 355 |
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I'll hook a meter up to the battery. I'm guessing check voltage while engine is off, at idle, and at 1000 rpm or so. What are the correct parameters for a six volt system?
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Thanks,
John Cotner New Ulm, Minnesota |
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TERRY
Member Sponsor Member Joined: 22 May 2007 Location: BOULDER COLORADO Status: Offline Points: 3400 |
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At least 2000 rpm or more to evaluate regulator output. Leave the lights off in case the voltage is real high as 6v bulbs will fail. Maybe PO had a 12v generator built??
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BOULDER 48 2A
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John Cotner
Member Joined: 11 Sep. 2014 Location: New Ulm, MN Status: Offline Points: 355 |
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Battery voltage with engine off: 6.49 Battery voltage at idle (640 rpm) engine warmed up: 7.05 Battery voltage @1000 rpm: 8.26 Battery voltage @2000 rpm: 8.18 I noticed when revving the engine from idle the ammeter pegs up to 40, then settles down to just on the plus side of center.
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Thanks,
John Cotner New Ulm, Minnesota |
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TERRY
Member Sponsor Member Joined: 22 May 2007 Location: BOULDER COLORADO Status: Offline Points: 3400 |
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Regulated voltage spec is 7.1 to 7.3. The manual describes how to adjust the regulator (section I). Or, a new reg is a Standard Motor Products VR2.
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BOULDER 48 2A
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TERRY
Member Sponsor Member Joined: 22 May 2007 Location: BOULDER COLORADO Status: Offline Points: 3400 |
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I forgot to mention, all connections between the generator and regulator should be checked for cleanliness, shorts, opens, and a proper ground from reg to generator.
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BOULDER 48 2A
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John Cotner
Member Joined: 11 Sep. 2014 Location: New Ulm, MN Status: Offline Points: 355 |
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Looks like my regulated voltage is a bit high. I'll check the manual to see if it can be adjust within spec.
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Thanks,
John Cotner New Ulm, Minnesota |
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