Fuel Gauge Issues

[1974ChevyC10]

last tuesday i replaced the starter on my truck.while i had it out i replaced the old nasty looking positive battery cable with a new one.well the old one had this j-shaped bracket that bolted to the fuel pump plate on the block and these 2 other brackets that held wires.well when i hooked up the new cable without any of these brackets and went to go start the truck the fuel needle moved halfway past the f mark.im not sure why the hell it did that so im asking you guys since i cant get a straight answer out of anyone else about this.one guy i work with says i should check the wires coming out of the fuel sending unit in the tank and my dad who has stuff to test wires and what not which i dont have well he is harder than hell to get anything done with.i wonder if maybe that bracket that bolts to the fuel pump plate could be a cause too since it didnt do this until i changed the old cable.all of the cables and wires by the starter too are out of the way of the exhaust as well.any ideas

[77bowtie]

If your needle is @ 3:00 you've lost the ground to your gage system.

[C-10volvo]

i have that same problem, but it will go crazy on me. it will say i have about a tank and a half, then the needle will go all the way over to empty or 1/4 tank. its really annoying me, and i have run out of gas once because of it. how do you check the ground? it the back of the fuel gauge? or at the sending unit? both?

[77bowtie]

That sounds like an intermittent ground. The ground connection is making & breaking contact. Something loose, wire, conection, connector. Your tank should have a ground wire going to the frame, right next to the tank. Check it. The frame is grounded to the cab Drivers side) Check it. The fuel gage is grounded to the firewall (inside) check it. Some where there you should find the problem. Good Hunting.....Jon

[1974ChevyC10]

Originally posted by 77bowtie
If your needle is @ 3:00 you've lost the ground to your gage system.

it is at the 3 o clock position.it just sits at that position it doesnt move at all.ill check all three of those grounds hopefully ill get to do it on thursday since i have that day off work.im sure its one of those but i still wonder about that j shaped bracket.maybe ill remove it from the old battery cable and put it on the new just to see what it does.thanks for the tip.Jim

[77bowtie]

Could that plate tie into a ground for part of your electrical system? Never underestimate the last owners ability to make changes.

[1974ChevyC10]

Originally posted by 77bowtie
Could that plate tie into a ground for part of your electrical system? Never underestimate the last owners ability to make changes.

thats along the lines of what im thinking....im going to put it back on thursday just for the hell of it and see what happens.if it doesnt make a difference oh well on to other grounds you mentioned

[77bowtie]

Yeah auto electrics can be a real "pita". The main thing to remeber is that on most its a 1 wire system. The body/frame/ engine block, act as the ground conductor for most devices. Good Luck...Jon