does the fuel sending unit have a ground and if its not good....
yetiwarrior82
Jeeper
- Posts
- 89
- Thanks
- 0
- Location
- Mass
- Vehicle(s)
- Stock 1979 CJ7
258 4.2L Inline 6
Auto tranny with quadratrac
-
Hello Guest, we are proud to now have our Wiki online that is completely compiled and written by our members. Feel free to browse our Jeep-CJ Wiki or click on any orange keyword when looking at posts in the forum.To dismiss this noticeclick the top right X.
does the fuel sending unit have a ground and if its not good....
- Thread starter yetiwarrior82
- Start date Start date:
- Last post Last post:
mylittlecj5
RIP Mike, we'll all miss you
Old Dog
Always Off-Roading Jeeper
- Posts
- 13,880
- Media
- 82
- Thanks
- 5
- Location
- Stonelick Lake, Ohio
- Vehicle(s)
- 83 CJ7 350 tbi, TH350, D300 twin sticked & clocked, narrowed Chief D44 Eaton Elocker & Moser shafts, Explorer 8.8 Detroit locker, 410's, RE 4.5" spring lift 1" body lift, 35" Claws, cage tied to frame, Corbeau baja seats, HD tie rod and draglink, u-bolts flipped, custom skid plate and sliders, Warn 9.5ti winch with Amsteel synthetic line
Yes it's a very common problem.
jasonmark1993
Old Time Jeeper
- Posts
- 1,366
- Media
- 10
- Thanks
- 2
- Location
- El Paso TX
- Vehicle(s)
- FJ cruiser (wifes ride)
2008 ZX10R,
73 CJ5, 408W, Toploader, Dana 20, 9" Dana 30 5.38 gears, next purchase=slicks
If you go to the drivers side and look in between the body and tank, you should see the ground wire. It should run to the frame kindof behind the drivers tire or towards the taillight assy. Mine was faulty and by itself.
yetiwarrior82
Jeeper
- Posts
- 89
- Thanks
- 0
- Location
- Mass
- Vehicle(s)
- Stock 1979 CJ7
258 4.2L Inline 6
Auto tranny with quadratrac
but should it be attached to the toop of the tank? and if so i don't have one lol
jasonmark1993
Old Time Jeeper
- Posts
- 1,366
- Media
- 10
- Thanks
- 2
- Location
- El Paso TX
- Vehicle(s)
- FJ cruiser (wifes ride)
2008 ZX10R,
73 CJ5, 408W, Toploader, Dana 20, 9" Dana 30 5.38 gears, next purchase=slicks
Correct; you should have two wires on there. One goes to ground, the other to the gauge.
yetiwarrior82
Jeeper
- Posts
- 89
- Thanks
- 0
- Location
- Mass
- Vehicle(s)
- Stock 1979 CJ7
258 4.2L Inline 6
Auto tranny with quadratrac
well then i think thats my problem. if its not grounded will that make a short at the fuse box to make my guage not work?
jasonmark1993
Old Time Jeeper
- Posts
- 1,366
- Media
- 10
- Thanks
- 2
- Location
- El Paso TX
- Vehicle(s)
- FJ cruiser (wifes ride)
2008 ZX10R,
73 CJ5, 408W, Toploader, Dana 20, 9" Dana 30 5.38 gears, next purchase=slicks
Well it won't make a short but it leaves you with an "open" circuit. Most electrical problems are "open circuits", not shorts. Fuses are there to prevent fires in the case of a short. The most common short is a positive wire rubbing on a grounded surface and then you either have a blown fuse or it keeps creating heat until something gives. Most of the time you just burn all the way through the wire and THEN you have an open circuit.
All electrical systems have to come full circle. Many run "across" something to make it operate. For instance the starter. It has power running in through the positive side and is grounded through the block back to the battery.
In the case of your gauge, its just measuring the resistance that the sender causes as it moves up and down with the fuel. One way to test a gauge like this is to remove the wire that goes from the gauge to the sender and ground it. It should peg the gauge one way or the other. Of course, if something else is wrong (no power to gauge, faulty gauge, etc) this won't work. So with no ground wire, you essentially have nothing connected to the gauge.
All electrical systems have to come full circle. Many run "across" something to make it operate. For instance the starter. It has power running in through the positive side and is grounded through the block back to the battery.
In the case of your gauge, its just measuring the resistance that the sender causes as it moves up and down with the fuel. One way to test a gauge like this is to remove the wire that goes from the gauge to the sender and ground it. It should peg the gauge one way or the other. Of course, if something else is wrong (no power to gauge, faulty gauge, etc) this won't work. So with no ground wire, you essentially have nothing connected to the gauge.
yetiwarrior82
Jeeper
- Posts
- 89
- Thanks
- 0
- Location
- Mass
- Vehicle(s)
- Stock 1979 CJ7
258 4.2L Inline 6
Auto tranny with quadratrac
well what is happening with mine is when i connect the fuse to the place that powers the gauges it blows once i turn the key
jasonmark1993
Old Time Jeeper
- Posts
- 1,366
- Media
- 10
- Thanks
- 2
- Location
- El Paso TX
- Vehicle(s)
- FJ cruiser (wifes ride)
2008 ZX10R,
73 CJ5, 408W, Toploader, Dana 20, 9" Dana 30 5.38 gears, next purchase=slicks
Ok, thats different. Thought you were just missing the ground wire at the sender.
So, one of the positive wires is probably touching ground somewhere.
Its possible that a gauge is shorted internally but I've actually never found that.
If its the circuit for the gauges, find a wiring diagram so you know what else/where those wires go/come from. It's possible you are powering other things too. You can do some continuity testing with a voltmeter if you have one. Or just start tracing them until you find the wire that is chaffed.
So you should have power coming into the back of the fuse box with the key on, and with the fuse in place, its sending that power to all the gauges.
With a voltmeter, you can stick one end into the fuse slot; only touch the side that goes OUT to the gauges. You can figure this out by testing which side gets power with the key on and the fuse removed. With the other end of the voltmeter, test each positive wire at the backs of gauges. Do this on Ohms and you should see 0.0. On the one that is touching ground (if this is the case) you'll see "ouch" or a higher number.
Another idea is to take a look up under there and try and follow the wires to look for the problem. Don't waste too much time doing that without forking out the $20 for a cheapo meter from autozone.
So, one of the positive wires is probably touching ground somewhere.
Its possible that a gauge is shorted internally but I've actually never found that.
If its the circuit for the gauges, find a wiring diagram so you know what else/where those wires go/come from. It's possible you are powering other things too. You can do some continuity testing with a voltmeter if you have one. Or just start tracing them until you find the wire that is chaffed.
So you should have power coming into the back of the fuse box with the key on, and with the fuse in place, its sending that power to all the gauges.
With a voltmeter, you can stick one end into the fuse slot; only touch the side that goes OUT to the gauges. You can figure this out by testing which side gets power with the key on and the fuse removed. With the other end of the voltmeter, test each positive wire at the backs of gauges. Do this on Ohms and you should see 0.0. On the one that is touching ground (if this is the case) you'll see "ouch" or a higher number.
Another idea is to take a look up under there and try and follow the wires to look for the problem. Don't waste too much time doing that without forking out the $20 for a cheapo meter from autozone.