Gas guage goes up while driving and down while idling.
Dash resistor? Gas gauge? ground issue?
New sender, new meter match.
Dash resistor? Gas gauge? ground issue?
New sender, new meter match.
Electrical opinion
- Thread starter jmustian
- Start date
That is interesting. If anything I would expect the opposite could be true. Did you use the 5v supply from the meter match or are you using the external volt limiter?
I installed a meter match earlier this year and it is pretty sensitive when I am driving around. The manual mentions something called the "Reading Average" that can be adjusted. Not sure how this would cause the needle to read so differently when parked vs driving though.
I installed a meter match earlier this year and it is pretty sensitive when I am driving around. The manual mentions something called the "Reading Average" that can be adjusted. Not sure how this would cause the needle to read so differently when parked vs driving though.
I didn't take the volt regulator off the dash. I hooked directly into wiring from float to gauge.
Same as instructions stated.
If you can test the Volt regulator that might be helpful. My VR worked when I held it just right but most of the time it just passed 12v to the gauge which is bad. I used the MeterMatch to provide the 5v power the gauge wants which is a nice feature so I didn't need to find a voltage regulator. That does require a slight solder modification to the MeterMatch but it is not difficult if you have ever soldered.
1970FuryConv
Old Man with a Hat
If you regard the fuel sending unit as resistance to ground, it is a fixed resistance to ground at a set fuel level.
The only variable may be the current coming from the alternator. If the alternator is not putting out enough amps at idle, the fuel sending unit has less current to ground. The fuel gauge reading then drops. With acceleration, alternator amperage increases, rectifying the problem.
IOW, a low amperage alterator or a worn voltage regulator that only partially controls the alternator could be the problem. Resistance in the ignition wire circuit that leads to the voltage regulator is also a possibilty. I would start the car and compare voltage output at the alternator to voltage at the voltage regulator connector.
The only variable may be the current coming from the alternator. If the alternator is not putting out enough amps at idle, the fuel sending unit has less current to ground. The fuel gauge reading then drops. With acceleration, alternator amperage increases, rectifying the problem.
IOW, a low amperage alterator or a worn voltage regulator that only partially controls the alternator could be the problem. Resistance in the ignition wire circuit that leads to the voltage regulator is also a possibilty. I would start the car and compare voltage output at the alternator to voltage at the voltage regulator connector.
@1970FuryConv Makes a great point. A simple check could also be to hook a battery charger up which should bring the voltage up closer to what you'd see at cruise. Just a thought.
I think I fixed the issue. Poor dash ground. But I ran out of gas hahaha
Ticked again but lights quit. One feed dead. Neutral switch dead, one feed dead. Temp light switch stuck in cold, regardless of new switch and wire seems ok. Numerous other ground issues. Fuse box was burnt out on starter circuit and alternator circuit so both have been bypassed. Checked bulk head connectors and none look great. I hate electric and dread having to replace wiring and box. Everything seems to ruin back to box.
1970FuryConv
Old Man with a Hat
Another option is to pull the dash and then mark and remove all wiring. Then correct everything.
I did that in 2016 with my 1970 Fury. I removed all the black electrical tape and corrected each short and contact corrosion. I ended up keeping my fuse box and bulkhead connectors.
Guess that's the next route. Fuse box is melted at Alt and starter, so have to replace box. Here's a pic of battery and relay where I was cleaning up wiring. Battery has 3 wires instead of 1 and relay has extra wiring at double feed.
My fsm does not say what size fusible link I should have which isn't there.do you know?
Well couldn't find a fuse box connector yet. Fuse box looks good but connector on back has couple burnt ,melted connectors. Might can repair them.
Maybe the wiring diagram would show the size of the fusible link?
You can probably source another bulkhead connector on ebay if you want to replace yours.
Seeing those pictures, this seems like the best/safest option. It isn't a terrible job if you label everything and take pictures along the way. Then you'll know the state of your electricals.
You can probably source another bulkhead connector on ebay if you want to replace yours.
Seeing those pictures, this seems like the best/safest option. It isn't a terrible job if you label everything and take pictures along the way. Then you'll know the state of your electricals.
I wonder how bad it would be to update to a modern fuse box instead of fixing this mess. Most of the 69 300 parts seem to be different and rarer than the 68 and 70. Not sure why the changes
That is what I did. I started by carefully removing the engine wiring harness and labeling everything. Then I laid it out on a piece of pegboard and started to repair or replace all the wiring and connectors that were worn/corroded. This was not terribly difficult just take your time.
Once I had that done I reinstalled the engine harness and then did the exact same thing with the wiring in the dash. That is when I decided to forego the glass fuses with the new blade style.
If you truly hate electrical this may not be the job for you. But if you take your time and have a good wiring diagram for reference it is a rewarding feeling to have safe and working wiring.
Once I had that done I reinstalled the engine harness and then did the exact same thing with the wiring in the dash. That is when I decided to forego the glass fuses with the new blade style.
If you truly hate electrical this may not be the job for you. But if you take your time and have a good wiring diagram for reference it is a rewarding feeling to have safe and working wiring.
I think I'll go that route. I can take one connector at a time from the bulkhead and work on that circuit. I probably won't remove the harness but check each wire from end to end. I'm going to try and clean the fuse box first and see if I can repair the burnt bulkhead connectors. If not they are available from the mopar rapist online.
Funny how the exact Chevy part is 1/10th the price of the same mopar part.
Funny how the exact Chevy part is 1/10th the price of the same mopar part.
The cooler the car the pricier the part! 
Similar threads
