Fuel Gauge

[Rumrunner]

I've been from time to time, and spent a lot of time trying to get my fuel gauge to work.(years) off and on. And I've asked the forum for ideas before and believe me I tried all the suggestions.
There has been a lot of time put into this.
At first when I hooked up a wire from the battery ground to the connection behind the kick panel ot the fuel gauge, it jumped around then finally showed it to be working. Playing around yesterday, I hooked up the same wire and nothing. I have never left the ground from battery hooked up for long. is my gauge bad? Has my gauge been bad the whole time?
Look up my other fuel questions if you havn't already. What am I doing wrong?

 

[V.R.D]

i believe the test in the factory service manual would tell what the problem is. the test will tell you to ground the wire at the sending unit to ground if the gage goes to full the gage is good . don't take my word read the service manual.

 

[Russ69Runner]

loose or dirty connection would be my thought. Had my hole dash cluster reworked so would not have any problems. Now just for a thought when hooked up to the sending unit and it works then don't might have a broken wire in the harness going to the tank from the front. Just some thoughts. Did have to bend my pic up tube in the tank so I would get the right reading. More to the front of the tank and in the middle. So, like stated go to your manual on how to test the system. I know it is frustrating but have patinas with electrical issues.

 

[Rumrunner]

I have been mustering all the "patinas" I have!
thanks for the advice.
1st pic about six months in, next ones current, about 4yrs, so far.
Car needs serious detailing right now. I'll get some more pics when it's clean.

 

[Russ69Runner]

Looks good. Know how much work we put into these old cars.

 

[Rumrunner]

OK, I've removed the dash cluster, tested the fuel gauge and it's working, tested continuity from tank to gauge cluster connection and there is continuity, when I bench test sending unit it shows very close to the correct ohm range, I've added a grounding from the tank to the frame and a ground to the sending unit, made sure the dash cluster is grounded. Hook it all together and the fuel gauge still does not work.
My hands are in he air!

 

[Russ69Runner]

I am puzzled why it doesn't work. It seems you have checked all the bases. This is a head banger for sure. I would run a ground wire from my batterie to the sending unit for a test. There is something that we are not seeing. It all seems to be right, but do you have fuel line ground strap on at the tank. Had to ask. I feel for you electrical issues can drive you nut's.

 

[Rumrunner]

Russ, Thanks for all your replies, you've answered a lot of questions over the years, don't give up on me. i don't know quite what you mean by "fuel line ground strap", most of my fuel line is rubber. I have added a ground from the tank to the frame and have ran a ground from the battery to every part of the sending unit at different times. When I run a line from the ground on the battery to where the wire hooks up on the sending unit the gauge works. After reading your response, I just got back from checking from the sending unit to the gauge with a ground from the battery and the gauge is working.
You've mentioned in my past inquires about new sending units being bad. This is my third sending unit and it is real close to the ohm range that has been mentioned before on this site.
?????????????????????????????
Confused Rookie!

 

[Rumrunner]

Pulled sending unit and found what might be an issue.
Ordering a new one and will get back to you.

 

[V.R.D]

grounds are so important almost more then positive get a ground strap to go to the engine from battery then engine to body and battery should have a ground to engine and a small wire to the body. sand all ground spots to bear metal and use dielectric grease so it wont cored / rust

 

[Russ69Runner]

Bought my ground clamp off Ebay. It goes to the fuel output tube of the sending unit. I ran a #6 wire through the hole car for a ground source. This is because I was an electrician and always wondered why they did not run one when building cars. This was to make sure I had a good ground from the batterie. Pig tailed off it for various connections. It is a backup incase the frame ground goes south.

 

[Russ69Runner]

521 restorations sells it. I also soldiered a ground wire to it. It connects to the pipe from the sending unit to the fuel line. This should make a solid connection for the ground of the fuel line. Do you have a ground to the fire wall from the engine and a ground from the batterie to the motor. Sold on E bay for GTX-Charger- Roadrunner. If you put a ground wire on the strap as well, you can ground it to a frame bolt. Hope this helps you out.

 

[Rapid Transit]

Don't get a stainless one. (If they are even still available ).
They have no spring tension.
Ask me how I know.

 

[V.R.D]

grounds are so important almost more then positive get a ground strap to go to the engine then engine to body and battery should have a ground to engine and a small wire to the body.

 

[Rumrunner]

I have a ground from the battery to the engine, battery to body, engine to body, fuel tank to frame.
As a uni body I would expect the body would ground the frame? I have also ran a temporary ground from the battery to the sending unit. Upon removing this sending unit I noticed one of the tabs holding the part that reads the amount of fuel got broken off and that part was not completely together.

So on the sending unit , run a ground fro the sending unit fuel line, skip over the rubber and attach to the fuel line?

 

[Russ69Runner]

That is what the strap dose in the photo. But like stated added a ground wire to the strap also that went to a frame bolt and my ground wire that was run through the hole car. A separate grounding system That I had added just for insurance purposes. Sorry you found the fuel sending unit in bad shape. But maybe you have finally found your problem. Summit sells the unit and Parts mix. The quality of these is not what we would like but we are stuck with a supply problem with where they are manufactured. Hope this will finally solve your problem and get you back on the road.

 

[Rumrunner]

I have not ordered the ground bar shown above
Got the new sending unt (4th one) Hooked it up and nothing. Ran a ground wire from the battery to the fuel line on the SU and nothing. Ran a ground from the battery to where the wire hooks up to SU and shows hte gauge is working and it also showed the wire to the SU was making contact. I also ran a ground from the SU skipped over the rubber and clamp it to the metal fuel line. Repaired the last SU and tried all above, Nothing.
I feel it is something so simple that I'm missing.
I tired of beating this dead horse but thanks for all your patience.

 

[Carl Ray]

Disconnect signal wire from tank, hook up voltmeter, how many volts do you read with key on?

 

[Russ69Runner]

Is the unit in the tank. Did you put fuel in the tank. You could test the unit out of the tank by wiring it up outside the tank and work the float by hand and set it to whatever and see if the dash gauge works. Maybe Carl is on to something by seeing if you are getting voltage to the sending unit.

 

[Rumrunner]

Do you mean run a 12 volt lead to the positive side of meter and ground of meter to the wire from the tank?
I know, rookie question, just don't want to make any more backward steps.