Fuel gauge issue

[slick willie]

I'm running a stock fuel tank and installed a new sending unit.. The gauge is stuck at ¼ tank when the sending unit is installed ( the needle does not move). I removed the sending unit and grounded it to the striker plate on the door and move the float up and down …. And it works.. but when I install it will not move… I know it sounds like a ground issue but I cannot get it to work while installed regardless of where I install it. Any suggestions

[1963c-10]

1st I'd clean the mounting surface for the tank/cab grounds. Also check to make sure the floats not holding fluid....this could give you a constant 1/4 tank reading.

If the sending unit works when out of the tank and grounded to the striker plate, then I'm inclined to think the sending unit is good....just grounding issue.

Does the gauge measure properly when you grounded the sending unit to the striker plate?

[cortcomp]

Do you have the ground wire from the sending unit to the inner back window panel connected? It will not ground well through the tank alone, nor should it.

[tincan1966]

It should just ground to the body, right above the tank. It is possible for the new sender to have a short in it and only be effected when installed and surrounded by fuel.

Remove the lead wire that goes from the sender to the fuel gauge(brown wire) Check for continuity from the post that wire connects to, to ground. There should be resistance. Depending on how much fuel in tank, you can estimate the ohms. 1/2 tank would be roughly 15 ohms(based on 0-33 ohm sender) If memory serves, should have less resistance at full than at empty, but I may not be correct- been a while since I checked one.

[cortcomp]

Even easier, clip a jumper wire or cable from the body of the sending unit to somewhere with a good ground with it installed and see if it reads right.

[slick willie]

i do have the ground from the tank to the body installed and I did pull the float and it is not holding fluid. It looks like the quick test is for me to run a ground to the frame from the sending unit. Then test the ohms (the tank is full) so the ohms should be high close to 30? Thank you guys I'll let you know the out come.

[ACK]

Just curious, have you checked the wire between the fuse box and the sending unit? Sometimes the casing rubs off and shorts out under the carpet.

[tincan1966]

Originally Posted by slick willie

i do have the ground from the tank to the body installed and I did pull the float and it is not holding fluid. It looks like the quick test is for me to run a ground to the frame from the sending unit. Then test the ohms (the tank is full) so the ohms should be high close to 30? Thank you guys I'll let you know the out come.

If you can ground it to the striker bolt and it works, your problem is not the body ground, it's the ground connection between the sender and the cab when installed.

Also, the wire from the sender to the gauge must be ok, or it wouldn't work while removed and moving the float arm up and down.

[ol_skool_chevy]

also be sure the float bowl is not rubbing the inside of the tank