I need to track down the reason my gas guage doesnt read accuratly. When I start the car the guage goes to full. After driving for while the guage will read what I assume is accurate. I figure I need to get an ohms reading on my guage and from the sending unit. Anyone care to lend some help here????
Grounds........check the grounds. Sounds like either you have a bad ground wire.....or it is quite possible the unit is just dying.
I agree with Mike's Dx. I have changed two sending units within the last year-- one was on our 70 convt. The Sx was it read full all the time. The issue was in the unit in the tank. Get the new bolt and nut kit, a new sending unit , an anti squeak roll for the top of the tank and perhaps the straps. Replace the straps if needed too. All the parts are in The OPGI and the YO catalogs. There is a black ground wire running from the unit on top to a lug near where the two prong plastic vent sticks up on the front of the tank, passenger side. Moving this lug while someone looks at the gauge may reveal the ground connection is compromised. Jim Lore
Check the ground wire and remove and clean the connection to the frame. It is very likely that this is your problem.
This tells me that you have a poor body to frame to engine ground, or a poor ground on your instrument cluster. Your engine has a direct ground via the batt cable, but since there may be a poor ground to the body from the engine/battery when you turn on the lights it creates greater resistance on the rest of the circuits....... The same could be true of the instrument cluster. You may need an Ohm meter (DVOM) to check these out. Test between the black ground wire on your headlight plug in to the batt - cable....there should be very little resistance .6 ohms or less. If you don't have a DVOM, you can just try running a jumper wire from the GND wire of the headlamps to the NEG batt terminal.....then try the lights and see what happens. Every old car I have ever had has had ground problems with the headlamps, or the plug ins on them,.
Great advise guys I will be checking that out. I have the guage out already and was hoping that was it. Sounds like I need to empty the tank and do some checking.
You do not have to drop the tank to check ground from the sending unit to the frame-- you can see one end and feel the other. Jim Lore
It must be at the cluster. I had a dash fire once when the detent cable decided to be ground - it was my first (only) engine swap years ago (don't ask ). I have since made sure the frame/body/engine grounds are very good.
I used to own a chevy caprice 1987 and when ever i pressed on the brakes the gas gaugae said I had a full tank and another half. Later it didn't work at all and I found the problem. Wires rubbed against some metal and spliced together. I need to buy a new sending unit.
