Low reading gas guage

[Cornpatch MO]

I know this subject has come up several times, but my limited search abilities cannot find it.
I just purchased a 1968 Plymouth Sport Sattelite. It has a new gas tank and lines and I am sure it has a new sender. The gas guage works, but when the tank is full, the guage reads 3/4 full. It also reads about 1/4th lower at lesser levels. Any input please.........................Thanks.................MO

 

[Dennis H]

http://r.search.yahoo.com/_ylt=A0SO...uel-tank/RK=0/RS=2YowbE2vhOPNM1n1OK165J9i7bY-
Characteristic.

 

[badlite]

Pull sender and bend float rod to obtain correct reading.

 

[Moparsmitty]

Don't be so sure that it has a new sender unless you have seen it. It might also not have the correct sender or be adjusted correctly. The only way you are going to know for sure is to drop the tank and have a look. The gauge in my 64 Belvedere reads about 1/8 lower than actual and I've gotten so used to it that I hardly ever think about it anymore. You have to decide if it is worth dropping the tank to fix it.

 

[Cornpatch MO]

http://r.search.yahoo.com/_ylt=A0SO...uel-tank/RK=0/RS=2YowbE2vhOPNM1n1OK165J9i7bY-
Characteristic.

That is the thread I was looking for . Lots of info to check out.
True that the voltage limiter can affect your dash lights? mine are dim. I thought the v limiter was just for the guages...........Thanks for some very valuable help.................................MO

 

[miller]

Link don't work for me. Probably my lousy PC.

Haven't gotten into my brand new, store bought fuel sender, yet. No tank, yet. But, think I've heard the ohms range needs to match the gauge. Not positive on that. Have a few old ones I'm going to compare.

 

[bm02tj]

That is the thread I was looking for . Lots of info to check out.
True that the voltage limiter can affect your dash lights? mine are dim. I thought the v limiter was just for the guages...........Thanks for some very valuable help.................................MO

Fix the power to your dash as that can effect the reading as well as the grounding

 

[Ron Ward]

Don't be so sure that it has a new sender unless you have seen it. It might also not have the correct sender or be adjusted correctly. The only way you are going to know for sure is to drop the tank and have a look. The gauge in my 64 Belvedere reads about 1/8 lower than actual and I've gotten so used to it that I hardly ever think about it anymore. You have to decide if it is worth dropping the tank to fix it.

Not only does it have a new sending unit, it has been upgraded to 3/8" fuel line.... just in case there's a need for more fuel in the future.

 

[440roadrunner]

This could be a number of things..........bad connections in the entire system

Out of cal instrument limiter / regulator

Out of cal gauge unit

Sloppy replacement sender. This is a well known problem on A bodies........the replacement senders are ridiculous

====================

The "shops" used to have a checking tool for gauges. This was a switch box with three resistors inside. By buying resistors of that value, you can check the gauges at empty (cold), "middle of scale" and full / hot. Temp, oil, and fuel gauges are same movement.

The values are

L = 73.7 Ohms (empty)
M = 23.0 Ohms (1/2)
H = 10.2 Ohms (full)

EXAMPLE. "You used to" be able to buy a four pack of 100 ohm, 1/2 watt resistors from RadSHack. Wire all four in parallel, and this gives you a 25 ohm resistor. Hook this from the sender wire to ground, and turn the key to run. Let it sit for a couple of minutes. You should read close to 1/2 scale (middle) on gauge.