Fuel/temp guage issues

[chykov's76doba]

I was working on my 76 cordoba this weekend and noticed that after idling for about half an hour the temp guage hadn't budged off C.

I also thought I had fueling problems, because each time I went to fill it up I could only get a couple gallons in the tank even though fuel guage read "E" and I can see fuel in the neck of fuel tank.

Now I think that I have guage problems. The voltage meter seems to work as does the speedometer.

Any thoughts on what the problem might be?

 

[73runner]

My first guess is that your problem is the low voltage regulator that drops the voltage from twelve volts to that required to operate the gauges. Its mounted on the the back of the dash. But.....

Start with the basics to chase the problem down before digging into the dash ( never fun)

i also suspect fuse may be your problem. Start there. Next, check voltage to the gauges. Helps to have a wiring diagram out of the factory service manual. If the voltage is present (and is between four and six volts) then it may be sensors though I doubt it.

You say that the voltage meter works. That gauge works directly off the power running through the system and isn't a true gauge with separate sensor to feed it. It literally measure direction of power being produced by the alternator versus the power in the system as supplied by the battery. More power from the alternator than coming from the battery and the power moves to the battery and the direction of flow moves the needle to the charge side. The reverse moves it to the the "D" or drain side. The greater the difference, the greater the the needle moves...

good luck and let us know how it works out for you.

 

[chykov's76doba]

Thanks for the suggestions. I will check out the fuses and gauges.

I will let you know how I make up.

 

[chykov's76doba]

Changed the voltage regulator and replaced the old gauge with a new one and still nothing. I will check the ground at the tank, but would that have any effect on the temperature gauge?

Thanks for any input.

 

[PUNKN8R]

Voltage Regulator or voltage limiter replaced ??? Limiter is on back side of dash panel. Did you check the lead to the fuel tank sending unit? (my voltage limiter knocks 12 volts down to a 5 volt pulse to the fuel sending unit).

Also check the ground strap from fuel tank outlet to steel fuel line.

The temp gauge usually shares the same voltage supplied by voltage limiter through circuit board on back of dash panel.

Good luck and God speed !!!

 

[chykov's76doba]

Thanks, I meant I replaced the limiter which is located right behind the gauge. I will check the lead and ground strap as well.

 

[cordoba-rick]

One time in my first car a 1976 Cordoba, I replaced the radio and cut wires I should not have. Hey, I was young! Anyway, my temp and fuel gauge did not work after that. Back then, I went to the bone yard and got the harness I cut, replaced, and all was good. Did you swap stereo and cut any wires?

 

[chykov's76doba]

No, I didn't cut anything. the gauges haven't worked since I got it.

 

[chykov's76doba]

If it turns out that it's my sending unit, do I have to lower my gas tank to replace it, or can it be done in place?

 

[Dobaroy]

Yes, you have to lower the gas tank, if it is the sending unit. Just something to think about, maybe it is time for some aftermarket gauges? I never had much luck getting those old gauges working. Good Luck

 

[bee71]

Good luck. I had a 76 bought right off the showroom floor. Had it the longest of any cars I have ever owned, had to give it up due to rot from MI winter road salt.

 

[chykov's76doba]

Thanks. Another project!

 

[RWG75]

If the oil pres guage works, the limiter in the dash is working. Actually had one go poof on me while driving but thats another story. The usual problem with the temp guage is rust on the tip of the sender and/or inside the connector that pops on it.

The gas guage ya already figured out and if you drop the tail pipe you can get it out with the tank in place but its not easy. The thing to watch out for when dropping the tank is the vapor containment line to the roll over valve. If you try to pull it off the valve, the nipple will break and your SOL. Cut it somewhere and use a connecter to splice it back later.

Suspect you're still looking for a sender, so try this:
http://tristarrradiator.com/Products Page/Products Page.html

 

[chykov's76doba]

If the oil pres guage works, the limiter in the dash is working. Actually had one go poof on me while driving but thats another story. The usual problem with the temp guage is rust on the tip of the sender and/or inside the connector that pops on it.

The gas guage ya already figured out and if you drop the tail pipe you can get it out with the tank in place but its not easy. The thing to watch out for when dropping the tank is the vapor containment line to the roll over valve. If you try to pull it off the valve, the nipple will break and your SOL. Cut it somewhere and use a connecter to splice it back later.

Suspect you're still looking for a sender, so try this:
http://tristarrradiator.com/Products Page/Products Page.html

I installed a new temperature sending unit and now the temp guage works, so it looks like it is probably the fuel sending unit. Thanks for the link. I may be contacting those folks.

 

[chykov's76doba]

Got the fuel sending unit out without having to remove the tail pipe! It was the float, had a pin hole leak and was full of fuel. replaced with a new float and fuel filter(strainer). Now all gauges work great!

Thanks for all your help!

 

[73runner]

Nothing beats the feeling of getting something to work again. Congratulations.

 

[chykov's76doba]

Nothing beats the feeling of getting something to work again. Congratulations.

You got that right!

But the feeling is fleeting as there always seems like something else needs attention.

Onto replacing the rear bumper! If I can get the rust encrusted bolts off!

 

[Jonnyuma]

Does the voltage limiter effect the dash/gauge lighting as well as the gauge function?

 

[chykov's76doba]

Does the voltage limiter effect the dash/gauge lighting as well as the gauge function?

I don't think so

 

[73runner]

Does the voltage limiter effect the dash/gauge lighting as well as the gauge function?

No. The dash lights are controlled solely by the rheostat that controls the lights.