Re: Roadrunner fuel gauge not working
[Re: 440challenger]
#482537
09/29/09 08:13 PM
09/29/09 08:13 PM
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Joined: Feb 2003
Posts: 4,503 NJ
440challenger
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OP
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Ok spent a few more hours under the dash, still nouthing. I hooked up my amp gauge- no change I disconnected my autometer fuel gauge. I took the sender wire i had ran to my autometer gauge, and put in directly to the NON flashing power stud on the gauge itself. no change. My dash (backlights) do not work,or sometimes just a few work. There is NO power to the (instrument fuse ) on my fuse block ,it uses orange and tan wires. I put powere to it ,but that didnt give me anything either. I tried running additional ground wire from the cluster to a good ground, with no change. My dash dimmer wheel only turns on my dome light, it does not dim the dash lights (which i do not have). Not sure where to go with this... The back of the gauge has a Flashing power ,so it must be getting power.. Not giving up yet,just stumped....
Last edited by 440challenger; 09/29/09 08:15 PM.
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Re: Roadrunner fuel gauge not working
[Re: 440challenger]
#482538
09/29/09 09:53 PM
09/29/09 09:53 PM
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Joined: Dec 2005
Posts: 60 Bethlehem, PA
Beemeister
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Joined: Dec 2005
Posts: 60
Bethlehem, PA
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Does your temp gauge work correctly? If so, the VR is OK. Look at the picture. Note the 3 slots where your voltage limiter plugs into. The center (with the extra lead from the capacitor) must have steady 12 volts referenced to ground. The terminal to the right is pulsed 12 volts which averages to 5 VDC, so a test light will flash from that point to ground. the terminal to the left of center is ground. See the threaded stud directly below the center VR terminal. That is the side of the fuel gauge that goes to the tank sender. With the ignition key "off" measure resistance from that stud to ground. You must have from 10 to 75 ohms depending on tank level(10=full). Next, plug in voltage regulator, turn ignition key to on and use test light on stud to ground. You should see a flashing test light, or varying voltage with a multimeter. If you got that, its gotta work!
'70 Coronet 500. Now 440/727. AC/ps/pb
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Re: Roadrunner fuel gauge not working
[Re: Beemeister]
#482539
09/29/09 10:05 PM
09/29/09 10:05 PM
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Joined: Dec 2005
Posts: 60 Bethlehem, PA
Beemeister
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Forgot to add:
1. Gauge resistance between the 2 threaded studs ~12.5 ohms.
2. Check those two fuel gauge nuts for tightness and corrosion. Mine were loose and caused a low tank reading.
The dash can be bench tested with a 12 volt power supply and a 100 ohm, 2 watt potentiometer, or some 5-10 watt resistors in the 10 to 50 ohm range.
Last edited by Beemeister; 09/29/09 10:07 PM.
'70 Coronet 500. Now 440/727. AC/ps/pb
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Re: Roadrunner fuel gauge not working
[Re: 440challenger]
#482543
09/30/09 09:32 AM
09/30/09 09:32 AM
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Joined: Dec 2005
Posts: 60 Bethlehem, PA
Beemeister
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I'll have to check the schematic to be sure, but if the center VR terminal is getting 12V steady, that's all the fuel and temp gauges need to operate.
The VR needs a load to begin pulsing. Since the temp sender is disconneced, the load must be the fuel sender, unless there is a short circuit somewhere.
When you get the volt/ohm meter, make the resistance measurements as described above, and verify with the voltmeter that 12 VDC is at the center terminal of the VR.
If you MOMENTARILY connect the output side of the fuel gauge (threaded stud) to ground, the gauge needle should move toward full. If you keep the gauge grounded for more than 5 or so seconds, the gauge will burn out. Once the needle reaches near the full mark, remove the short immediately! It is safe to ground through a 10-50 ohm resistor.
'70 Coronet 500. Now 440/727. AC/ps/pb
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Re: Roadrunner fuel gauge not working
[Re: 440challenger]
#482545
09/30/09 10:21 PM
09/30/09 10:21 PM
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Joined: Dec 2005
Posts: 60 Bethlehem, PA
Beemeister
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That might be the problem right there - burned out or otherwise defective fuel gauge. I would put the 12.7 ohm gauge in that dash.
I also highly recommend the 5 volt solid state gauge voltage limiter. With this device, shorting the gauge output to ground won't destroy your valuable gauge, like the pulsing stock original VR will.
You can do this mod for < $5.
'70 Coronet 500. Now 440/727. AC/ps/pb
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Re: Roadrunner fuel gauge not working
[Re: Beemeister]
#482546
10/01/09 07:06 AM
10/01/09 07:06 AM
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Anonymous
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Anonymous
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i know this won't cure the fuel gauge problem but if i remember correctly the tan wire and instrument fuse won't be hot all the time, only gets power when the lights are on.
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Re: Roadrunner fuel gauge not working
[Re: 440challenger]
#482548
10/04/09 06:45 AM
10/04/09 06:45 AM
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Joined: Feb 2003
Posts: 4,503 NJ
440challenger
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Posts: 4,503
NJ
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IT WORKS!!!!!!!!!!! Took my original gauge put it in the cluster i purchased that had the bad fuel gauge. Must of been the circuit board on my old dash that was bad? Only thing now is I have no dash lights at all. Could that happen if my dimmer switch is bad? If I turn it all the way my doem light goes on... I did notice a Heavy PINK wire out of the main dash harness is cut. Then more towards the right side of the dash there is smaller pink wires with mutliple spade connectors(from the factory) but it doesnt look like the heavy pink could connect to the smaller pink wire. ahhh..the fun goes on. Thanks for the info on testing the gauge though!!!
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Re: Roadrunner fuel gauge not working
[Re: 440challenger]
#482551
10/04/09 08:56 PM
10/04/09 08:56 PM
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Joined: Dec 2005
Posts: 60 Bethlehem, PA
Beemeister
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The gray wire to the clock comes off the fuse block. Fourth fuse from the left, I believe. However, if your car originally did not have a clock, the wire won't be there.
'70 Coronet 500. Now 440/727. AC/ps/pb
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Re: Roadrunner fuel gauge not working
[Re: 440challenger]
#482553
10/04/09 10:01 PM
10/04/09 10:01 PM
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Joined: Dec 2005
Posts: 60 Bethlehem, PA
Beemeister
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Yes, it must be a 12 volt feed, with 12 volts all the time. Play it safe and make sure its fused - just in case.
And don't rely on that clock for meetings, doctor appointments, or job interviews. You will never be on time.
'70 Coronet 500. Now 440/727. AC/ps/pb
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