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64 gas sending unit works removed, not when installed??
Posted: November 26, 2018, 3:36 pm
by aj64f100390-292
Hey guys, I have a issue with my gas sending unit...it only works outside the tank..but once it's inside it don't work at all even full and the float is good. The wires seem to be fine..only thing I can think of us that the voltage regulator..and the other gauges seek to act fine like they always have.
Thanks in advance
Re: 64 gas sending unit works removed, not when installed??
Posted: November 26, 2018, 6:15 pm
by unibody madness
are you running a separate ground to the sending unit when out of the tank.? could it be a bad connection when you place it in the tank?
Re: 64 gas sending unit works removed, not when installed??
Posted: November 26, 2018, 6:18 pm
by aj64f100390-292
unibody madness wrote:are you running a separate ground to the sending unit when out of the tank.? could it be a bad connection when you place it in the tank?
yes, and back story is that we replace the DC repop that was never right..junk...and it got to where sometimes it worked some times it didn't but started as only working at 1/2 or above..yanked that out and got a nos.
Re: 64 gas sending unit works removed, not when installed??
Posted: November 26, 2018, 6:19 pm
by aj64f100390-292
unibody madness wrote:are you running a separate ground to the sending unit when out of the tank.? could it be a bad connection when you place it in the tank?
we thought we had moved both wires in just about every position possible trying to rule that out..
Re: 64 gas sending unit works removed, not when installed??
Posted: November 26, 2018, 8:12 pm
by unibody madness
Center wire should be orange and it comes from the dash through the instrument voltage regulator same as oil gauge/idiot light, and temp gauge.
The ground wire goes from the tab on the edge of the sending unit to a good ground, not on the tank, usually screwed to the brace under
the rear window.
Good luck
Re: 64 gas sending unit works removed, not when installed??
Posted: November 27, 2018, 4:24 pm
by SteveCanup
The frustration is real...I had the same issue with mine. Intermittent readings...sometimes full, or not, or full or not...lol. After reading this, I went out today and installed a new ground wire to my sending unit and viola' (waa-laa) it works like it is supposed to. Mine is a mustang tank under the bed. The sending unit that came with it did not have a tang for the ground wire so I had to fabricate a place for it. Life is good.
Re: 64 gas sending unit works removed, not when installed??
Posted: November 27, 2018, 6:40 pm
by aj64f100390-292
unibody madness wrote:Center wire should be orange and it comes from the dash through the instrument voltage regulator same as oil gauge/idiot light, and temp gauge.
The ground wire goes from the tab on the edge of the sending unit to a good ground, not on the tank, usually screwed to the brace under
the rear window.
That's exactly how it's wired..nee ground wore as well
Good luck
Re: 64 gas sending unit works removed, not when installed??
Posted: February 2, 2019, 8:44 am
by mongrot
Try running a test light from a hot wire (at fuse box or ignition) and touch the end of the tester to the top of the sending unit to verify the ground. Maybe the cab isn't properly grounded. If the ground is good, disconnect the gauge and run a separate jumper wire from the gauge to the sending unit terminal ( replace the orange wire). Has to be wiring if the unit and gauge work when removed. Also there has to be a decent amount gas in the tank for the sending unit to register anything. Probably 4 gallons or so.