The Stovebolt Site Forums The Shop Area The Electrical Bay FUEL TANK AND GAUGE

my 66 c-10 has a new tank, back of seat, new sending unit
however, no matter how much gas is added i read less than
1/4 tank, so i assume, bad word to use, its the gauge
this is the original gauge in the cluster. if i install
a aftermarket gauge does this have to be calibrated
to gallons in the tank??? dumb question i guess!!!!
what is the capacity of the original tank????

Make shure you have a good ground from the sender to the cab. Remove the wire from the sending unit & turn on the ign. The gauge should run way up beyond full. Ground the wire & the gauge should read empty. If this doesn,t happen the gauge or the wireing is bad. If it does remove the sending unit & hook the wires or jumper wires to it. Move the float rod up & down. The gauge should follow it.

did exactly whwt you said, gauge did everything it was supposed to do, when wires were connected as you said, im
reading less than 1/4 tank with ignition off, when i turn ignition on, gauge goes to extreme empty rather than towards full position or half. is that a hint???-----thanks----john
what color wire from gauge goes to sending unit, i have
a birdsnest under dash, previous owner was no wirer??????

That's about all I know about it. I believe the wire to the tank is tan but might be orange. I wonder if the wires on the gauge are reversed. The reading when the ign is turned off is immaterial. They are made to stay in the same area.

chevyagain66,

When you did the test Wrenchbender outlined, did you perform it at the sending unit on the tank? If you did, and it proved the gauge and wiring good as you indicated, then it would seem that the problem is the sending unit.

When you attach the wire to the sending unit and turn the key ON, the gauge goes to full EMPTY, right. This would indicate to me the sending unit is shorted somewhere.

I think this rig has a connection point for the wire from the gauge, and the wire from the sender located in the fuse block. It isn't a fused connection, just a connection point. If your test proved the wire and gauge good, the problem should be the sender, or maybe some problem with the connection at the top of the sending unit.

PS. If this has NEVER worked since you installed it, don't discount the fact it might be stuck or the float has sunk, and it is indicating what it perceives as a EMPTY tank.

Stuart

okay guys thanks, ill keep checking my wiring, i know the
sending unit is new, got bill from last owner, gotta be
a wire somewhere-----------john

Something else to remember, the wire is a grounding circuit coming from the gage. The "Tan" wire is ground that runs through the sender and back out to the frame. The sender just varies the amount of ground so the gage will move depending on the amount of resistance. So if your bed,cab and frame are not well grounded, your gage can not work correctly. Runs some good quality ground wires from the sender to the bed, from the bed to the frame, and from frame to the cab. Don't forget about from battery to frame. Also, clean each spot of all rust and paint, and use Star washers under each wire connector.
You can never have to may ground wires! Joe

A fuel gauge that pegs to EMPTY when the key is turned on means there is a direct, or GOOD path to ground. If you did Wrenchbenders test at the tank, and the gauge reacted as he described, then the gauge AND wire clear back to where you are checking is fine.

If you have the key on and touch the wire to the proper post on the sending unit and the dash gauge pegs on EMPTY, either the tank is empty, the float has sunk or the sending unit is defective.

A insulated tank or any poor ground between bed, tank or cab would result in a FULL gauge reading.

It looks like the next step would be to pull the float/sender and take a peek.

This is how it looks to me.

Stuart

thanks stuart, and everyone, will pull sender see float condition, maybe hung up, or did the titanic on me----john

okay guys pulled sending unit, float is shot, all cracks
i was right did the titanic on me, does anyone know where to
get just the float without buying the whole unit, if anyone has one let me know please------------john
found a place that has the float, thanks to all!!!!

I always thought a new float came with a new sending unit.

it does, new sending unit was not installed by me, it was previous owner, cant understand why float was in such poor
condition, many cracks, especially at seam, oh well, it
was probably made on a friday as they say, oh by the way
saw your trucks, they look great!!!!!! i was lucky to find
just the float by itself, thought i would have to buy the
whole unit