El Camino Central Forum banner

1 - 9 of 9 Posts

·
Registered
Joined
·
566 Posts
Discussion Starter #1
The gas gauge in my '69 never seems to get above 1/4 full, even with a full tank (17 gal. I think). The previous owner said he measured the sender unit and got 90 ohms and 0 ohms when it was supposed to, but I haven't verified that for myself yet.

Should I be investigating bad grounds, or is it likely a mechanical issue (perhaps with the float arm)? The gauge is consistent, and doesn't flicker; it's just 1/4 when "full" and less when the tank empties.
 

·
Deputy Director, Region 4
Joined
·
929 Posts
Ground and electrical connections are certainly the first place to look. My rule of thumb is to check the easiest and cheapest things first. I like to presume that the systems have been designed for the ones easiest to fix to fail first. After checking electrical connections to the tank, check the gas gauge. If all the easy stuff seems okay, be prepared to budget some time to pull the tank and check internals.

But I bet it's the gauge.
 

·
Registered
Joined
·
566 Posts
Discussion Starter #3
Ground and electrical connections are certainly the first place to look. My rule of thumb is to check the easiest and cheapest things first. I like to presume that the systems have been designed for the ones easiest to fix to fail first. After checking electrical connections to the tank, check the gas gauge. If all the easy stuff seems okay, be prepared to budget some time to pull the tank and check internals.

But I bet it's the gauge.
Thanks Jim. How hard is it to pull the gauge?
 

·
Registered
Joined
·
532 Posts
if the sender ohms out right i would suspect a ground or power feed problem, guages do fail, but in better than 20 years of turning wrenches for a living i have never seen one fail, it has always turned out to be either a bad sender or a wiring problem, first thing with key on and sender unplugged check for 12 volts(where sender plugs in), look at your gauge, then ground the wire you just checked for voltage, look at gauge again, ect if you get the same results as you are seeing with empty and full tanks, then start taking the dash apart and checking from there. get a good flow of diagnosis and stick with it and you will get it figured out. GL
 

·
Registered
Joined
·
581 Posts
Sounds to me like a sender,unplug the wire to the tank sending unit and ck with key on.gauge move,next ohm wire 0 to 09 ohms and see if gauge goes empty to full if it dose it's the sender.
 

·
Premium Member
Joined
·
5,899 Posts
Sending unit wire un plugged - gauge should go past full with key on. Ground the sending unit wire and key on should go past empty.
 

·
Registered
Joined
·
566 Posts
Discussion Starter #8
Do I need to drop the tank to get to the sender? I can't quite see it when lying underneath the truck...
 

·
Premium Member
Joined
·
5,899 Posts
There is a disconnect at the very rear of it. Follow the wires coming from the top of the tank. The black one is a ground. Unplug the other one and see what happens.
 
1 - 9 of 9 Posts
Top