fuel guage trouble

[mr.terry66]

i know the problem is in one of four places. the gauge reads empty all of the time regardless of fuel level. the needle only moves a tiny bit when the ignition is turned on. i put a test light to the feed wire and got a steady pulsing light. i assume that is the i.v.r. doing its job. my guess is the sender is bad or the float is full of fuel.

what do you guys think, i don't want to replace parts i don't have to.

 

[86bluecobra]

I would say time to replace the sender myself.

 

[dennis112]

Remove the wire at the sender and ground it. With the key on does the gauge read "full?" If so replace the sending unit as it is bad. If not, need to check the wire to the gauge, and the gauge itself. Is it getting power from the IVR?

A bad IVR will typically also affect the temp and oil pressure gauge in a 66'. All 3 gauges normally act funky at the same time.

 

[mr.terry66]

the other gauges work fine so i think the i.v.r. is ok. i did ground the wire and nothing happened. i'm not positive that i got a good ground, i was trying to work fast. the wife has morning sickness all the time and really isnt in to working on cars right now and she was watching the gauge for me. i will try again.

what about supplying voltage directly to the gauge? wouldn't 3 volts give a half tank reading?

i really need to buy a f.s.m.!!!

 

[geostang351]

the other gauges work fine so i think the i.v.r. is ok. i did ground the wire and nothing happened. i'm not positive that i got a good ground, i was trying to work fast. the wife has morning sickness all the time and really isnt in to working on cars right now and she was watching the gauge for me. i will try again.

what about supplying voltage directly to the gauge? wouldn't 3 volts give a half tank reading?

No. What determines the needle moving is resistance provided by the sender. A full tank would send a signal of 73 Ohms of resistance and an empty tank would send a signsl of 13 ohms of resistance. I think the CVR provides a power of 5 volts for stock gauges.

 

[RUSTYNUT]

Make sure you have your sender has a good ground. Most of the time I found the 40 year old brass floats to be the problem. You can also test out of the tank. Just be sure to get a new gasket and to be safe I like to use a new retainer.