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First a quick recap:
1. Originally my oil pressure and fuel guages didn't work at all. The temp worked but always maxed out right past the C. When grounded all three went up all the way.

2. After installing new sending units, the temp and oil gauges show life, but the fuel reads between 1/4 and 1/2 when full (right above the E when the tanks 3/4 full) and the oil always reads right after the L. The temp guage still maxes out right past the C.

Today, I substituted all three sending units with a 10 ohm resistor to ground and all three settled at about 1/2. (When directly grounded all three still go all the way.) What does this mean and what is the next step in my mission to get the gauges working right.

Thanks again for all your help.
 

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After going through a month of frustration with my gas gauge lemme tell ya what I learned...
1. First, like Midlife said, check your grounds. ALL of them. Batt to block, block to Firewall, make sure they are clean and tight. Check gauge readings.
2.Hook one lead of a voltmeter set for resistance to the ground (the metal casing of the IVR) of your IVR and the other lead to a good clean ground needle should peg if ground is any good.
3. If you end up suspecting a bad IVR dont replace it with a cheap one. From reading and talking to people 2/3 of new, cheap, IVR's are NFG. I got a $50 Autolite from Mustangs Unlimited for my 65.
4. If you still have trouble try this for grins. Find a good ground near your gas tank (again, verify a good ground with voltmeter) I used a trunk latch bolt. Get a wire long enough to go between that ground and your tank + a few feet and strip both ends. Wrap one end around the metal part of the nipple on your fuel sending unit and secure it with a hose clamp. Ground the other end on the ground you found. Does the Gas gauge read more accurately? if so maybe you have 3 separate issues.

I hope this helps
John
 
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