66 Fuel Guage question

[CaptHutch66]

Scanned through the previous posts and couldn't find the same issue as I'm having soooo I hoping someone can provide the insight into what I need to do! New sending unit, good ground, tan wire connected to the fuse block in the correct place. Turn key guage jumps to "full" position (tank not full) turn key off guage slowly returns to the "E". Removed the guage from the dash to have a look at it....both green and red coil wire intact, needle is free w/no resistance! I'm stumped! Any help would be greatly appreciated!

[chevy_mike]

If you take the wire off the sending unit and touch it to ground, with the key on, the gauge should move to empty. Remove the wire from ground and it should go up above full. If it does this, likely your gauge is working and the problem is the sender. Remove sender, hook tan wire to it and run a jumper from the sender body to ground. Move the sender by hand and see if the gauge moves with it. If not, then sender is likely bad. If it moves correctly, then your sender is not grounding correctly.

If neither of these things work, likely some bad wiring/contact in the gauge panel to fuse block.

[TR65]

Captain,

Sounds like you might have a 90 ohm sender. That would make the gage read full with just a partial tank. Our trucks us a 30 ohm sender.

Check out these threads.

http://67-72chevytrucks.com/vboard/s...d.php?t=432957

http://67-72chevytrucks.com/vboard/s...d.php?t=413579

TR

[chevy_mike]

Actually my understanding is '66 was the first year they went to 90 ohm senders in the trucks. Prior was 30 ohm.

Now if his gauge cluster/gas gauge is from a '65 and earlier, that could account for an issue.

[CaptHutch66]

Thanks for all of the responses guys! Yeah I'm not sure what year the dash is I have three from the 60-66 year models and if there was a change within the dashpanel (mech/electric) other than cosmetic it would be hard to know! I have changed the location of my power on the fuse block and now I'm getting "1/2" tank reading! I'll keep my fingers crossed that its working properly now. If it was in fact the location of the power source at the fuse block then there would have to be some sort of metering source at the fuse block that throttles the amp/ohms. My fuse block has been painted over a couple of times so its hard to tell what is what. But again I appreciate all of the responses and the willingness to lend an opinion! Best site on the net for help and info!

[TR65]

Originally Posted by chevy_mike

Actually my understanding is '66 was the first year they went to 90 ohm senders in the trucks. Prior was 30 ohm.

Now if his gauge cluster/gas gauge is from a '65 and earlier, that could account for an issue.

I didn't know which year changed to 90 ohm. LMC and Classic Parts sell the same sender for 60-66.

CaptHutch66
Re: 66 Fuel Guage question
Thanks for all of the responses guys! Yeah I'm not sure what year the dash is I have three from the 60-66 year models and if there was a change within the dashpanel (mech/electric) other than cosmetic it would be hard to know! I have changed the location of my power on the fuse block and now I'm getting "1/2" tank reading! I'll keep my fingers crossed that its working properly now. If it was in fact the location of the power source at the fuse block then there would have to be some sort of metering source at the fuse block that throttles the amp/ohms. My fuse block has been painted over a couple of times so its hard to tell what is what. But again I appreciate all of the responses and the willingness to lend an opinion! Best site on the net for help and info!

If I am not mistaken, the fuse block is not the power source for the fuel gage. It is just a junction point. (If I am reading the wiring diagram correctly) The power comes from the ign. switch circuit.

TR

[CaptHutch66]

Mine has been painted over but heres a pic from a previous post; I assume this is the correct power source. If anyone knows different please advise.