On my 75 runabout the gas gauge doesn't work. Before i tear into it I am sure there is a commonality of problems that always show up. So before i start working on finding the issue i thought i would find out what the most common issues were and got from there.
Your thoughts?
jim
the float is usually the culprit. but as old as these are it could be the unit itself. or even a fuse.
Jim:
Have you checked your plastic housing behind the gauges? If it is cracked or falling apart, this could be one of the symptoms (connector is not making good contact). Also, your sending unit itself could be bad, in two ways:
1) Float is leaking - if you have a brass float an it leaks, it will never "ride" tyhe gas level properly, meaning that you need to replace it.
2) Unit is bad at the tank - these are easy to test, just use an ohmmeter on the leads to the sending unit. You should have anywhere from a few ohms to 75 ohms max (depends on gas level); anything greater means a bad unit.
Best wishes, I went through this myself and both my cluster AND sending unit were bad.
Chris
The float's are made of brass? When I took the sending unit out of my '74's tank it felt like the brittlest of plastics. It was also eggshell thin. ???
You'd be correct - mine was also plastic - but some >are< brass, which is why I mentioned it. Not sure what he would have!
Chris
I was going to ask if you had gas in it, but thought again so Hellfire wouldn't bring hellfire down on me. :embarassed:
I agree to checking contact at the gauges first, pulling a tank ain't fun if it's full.
CB:
When my buddy and I pulled the tank on my wagon (at his shop), it had about 8 gallons of old gas in it. Can't remember what happened to the gas after that :devil:
Chris
The tank gauge I believe works by grounding. I believe if you remove the sender wire at tank and jumper the wire to ground you can see if the gauge responds. Remember to turn the ignition on and leave it on only long enough to see if the gage does or doesn't respond.
If it doesn't then try the connection at the dash. Like most dash wiring the Pinto uses a copper trace on a plastic sheet. If the white plastic holding the gauge is deteriorating then there may not be sufficient pressure for contact. Tightening the nuts may restore contact. I say that "IF" the plastic doesn't crumble more.
Otherwise you need to pull the tank. A dead float will be obvious because it sinks. Test it in a solvent as water doesn't find its way into pin holes as easily. Sometimes the sender gets gummed up with varnish and can be cleaned. Also the connection with the resistive wire can be suspect. I soldered mine and had issues with the seal leaking. JB weld has held it leak free for over a year now.
Tom
As for dropping the tank (yeah it had about 8 gallons of bad fuel in it at the time) if I can do it anybody can. I was very intimidated by mine but it was deceptively easy. In my very humble opinion, as the gauge clusters seem to be very wafer-brittle I would attack the tank/sending unit first. If I was there I could do it for you, or advise you. I used the floor jack and some short boards to ease the tank down. :surprised:
excellent information. I expect i will try in this order:
fuse
sender ground
dash plug
sending unit... :mad: these are easy to test, just use an ohmmeter on the leads to the sending unit. You should have anywhere from a few ohms to 75 ohms max (depends on gas level); anything greater means a bad unit.
check wiring to the gas tank.
Anybody else?
If all else fails check the wiring that runs from the front to the back of the car. On my 78 one of the wires was actually broken so I had to run a new one. The wiring diagram shows it to be a yellow with a white tracer going to the gauge & black to ground at the sender itself
Thanks i will add it to the check list.
jim
According to the '79 Electrical Manual, everything is in a series. I'd start with a VOM at the tank sender. See if you have 12V at the yellow& white wire and a good ground at the black wire. Also check for corroded contacts where the harness plugs into the tank. I once did a quickie fix by wiggling that plug. If you don't have 12 back there, I'd move up to the dash and check for it at the gauge and that goofy mechanical voltage regulator that looks like a circuit breaker.
BTW, why do I want to call 12V the Vcc? ;) I could be real Old School and call it B+! ;D
You get it all fixed?
No not yet. I am hoping for this week. I will let you all know when it happens and what i find.