ebody fuel gauge issue

i have a 70-71 rally gauge. the fuel shows full all the time. i disconnected the wire to the sensor and it still shows full. any help is very much appreciated. thank you

I guess the easiest thing to check is how much voltage you get coming out of this wire when you have it disconnected with the ignition on.

You don't have any voltage out of this wire, it's a resistor to ground, it's the gauge which supplies current to it (and the amount of current going through it, in turn, makes the needle move).

Check the resistance between sender wire and ground, I'd say yours is zero, which would give maximum needle movement.

You will get a 5v power or pulsating power to the wire. The sending unit is the ground and supplies the resistence. With the gauge reading full all the time you either have a short to ground somewhere along the wire or a bad gauge.

You can have voltage without current but not the other way around.

So is the needle pegged or just "full" ? Anyhow... To give the simplified answer... Assuming the oil and temp gauges are working fine {which would indicate the limiter is still in check} there's only two things it could be{as already stated}...There's a short{ground} in the sender wire before the sender terminal or the gauge is shot...Next step {after the above tests}would be to pull the sender wire off the gauge wiring and see if the gauge settles to empty...If not it's time to yank the gauge for the rebuild..

i pulled the sender wire atthe tank and the gauge remains pegged. the kicker is the complete cluster was rebuilt by supposedly a pro in the carolinas.if the gauge is bunk they shouldnt it not move?

i just got under the dash and noticed a flashing red light on a small relay attached to the back of the cluster.. anyone one know what that is??

yes,i guess its the fancy upgraded instrument voltage limiter that blinks to show you that its ok.its some kind of upgrade?i havent got one but i bet another member knows more about it.i do think i know that there should be a few volts or 0,some pulsating out of that thing to the instruments.

Generally speaking if your

• gauge is good
  
• you have power to your gauge
  
• the gauge is pegged
  
• the gauge does not change when the wire at the sending unit is removed
  

It means there is a issue with the wire from the gauge to the tank, it is grounded (shorted to ground) somewhere

well im still dealing with the fuel gauge issue.... i removed the kick panel and unplugged the whole rear light harness which includes the fuel tank wire. and the gauge stillis pegged.i pulled the cluster out and reversed the 2 wires on the back of the guage and i get nothing so i put them back. i have another fuel gauge from a 72 -74 rally cluster.... anyone know if they are the same? thats my next shot at fixing the problem. crazy thing is... the manual says to put the wires on the post s where i get nothing. theres also 2 areas in the manual where it says to put the + and - wire on the post where 1 diagram says to put themone way and the other says the opposite way. manual is helpful but ive found several mistakes in the manual.

hot dog!!! i had another fuel gauge from a 72-74 cluster. plugged it in and shes working as it should. so even tho the gauge was pegged at all times.it is a bad gauge. soo whipe that one off the list. alli have left is the heater blower motor not operable. any input on that one is appreciated. thanks guys!

That's all I do, one item at a time.

well not so fast .. guess i jumped the gun.... i pulled the gauge as stated used a different gauge outside the cluster and worked fine. then..... i pulled the not working gauge in cluster. for curiousity i hooked it up outside the cluster and it worked fine... installed it back in te cluster and it pegged. how ya like that... after many hours of the this and thats. turned out that the condensor like thing on te cluster was doing something messed up. sooo heres what happened... i pulled the screw holding the condensor mounted the gauge with the condensor wire attached and it worked. i screwed in the condensor and it pegged. so i ended up pulling the condensor wrapped it in electrical tape. reinstalled it and it works fine. ive neve seen anythinglike it before... but nevertheless its installed with the original gauge and working fine with cluster installed. however my rebuilt clock stopped working. all i can suggest to everyone is DO NOT USE H&H AKA TACHMAN TO RESTORE YOUR CLUSTERS! i have power to the clock but it wont work. the tachman assured me a 2 year warranty and the fact is his work did not last 2 days. and thats just the clock never mind all the other stuff ive been dealing with on his work. i gave tachman 1500 to restore this cluster. and all i got was a ton of headaches and shoddy workmanship. i did fire up the motor but still have not seen if the temp alt and oil are working.so wish me luck on that one...

To me it sounds like something is shorting out on the board. I would contact this guy who restored the cluster. I'm sure if you told him what is happening he would instantly know what is wrong and where the short is. maybe there is something he forgot to install.

i did contact him..he basically said pay him even more money send the cluster back and he will look at it and then he will tell me how much more money he will need to fix his mistakes. soo that option is out of the question. plus having paid him 1500 to do it right and have it come back worst then when he got it is not a good idea to trust him. mind you he had it for 6 months and he told me after he received it to pay in full before he stated working on it. i paid in full 3 days after he received it..

I agree, stay as far away as possible from the CrapMan, he is without a doubt the worst vendor I've ever come across.

Well it sounds like the gauges are grounding out when installed. If you have another gauge assembly take a look at how they are installed and see if they are installed differently if there is a fiber washer missing or not.