fuel gauge update

[cjoenny89]

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Ok I pulled the brown wire of fuse block and turned key on and gauge went from 1/4 full to like 4 or 5 o'clock position way past full. plugged it back up and turned key on it went to empty.
I ohmed out the wire un-hooked from the fuse block to the tank connection to see if the wire was good and it was good but it also shows good when you touch the tank and not both end of the wires. could my problem be a pinch wire onto the frame or will I get this from one end of the wire to the other or to the tank it showed closed not open. It just acts like one big ground?
I thought I should have have showed open from the touching the tank to the end by the fuse block and only close from each end of the wire is this where my problem is coming from?
I even ran a ground from the batter to the tank and then tried it gauge still went to zero.
I am guessing I have my fuel sending wire pinched and is grounded out? or my sending unit is bad?
Thanks for the help!
Chad

[Baddflash]

Sounds like the problem is in the tank, most likely the float has a hole and has filled with fuel. I would say it's time to pull the sending unit out.

[cjoenny89]

ok I will try pulling it out sometime in the near future and get it fixed! Where is a good place to order a new one?

[Baddflash]

I would suggest pulling the unit first and confirming that the gauge moves with the sender. That said various places sell them like lmc truck, classic parts etc, they are cheap enough I doubt it matters where you get it.

[TBONE1964]

The fact that you pulled the tan wire from the fuse panel and the gauge went to past full (between 3 and 5 o clock) tells me that the gauge is capable of working as it should.

What exactly is the problem you are having? If the gauge will not move past 1/4 tank no matter how much gas is in the tank, the likely cause is the fuel gauge resistor is bad. It will be the small ceramic piece on the back of the fuel gauge and is color coded. It will probably be orange, red or blue. If you remove the resistor and do an ohm test on it, it should be around 100 ohms. If it is not close to that number, the resistor is bad.

Have you done an ohm test on your sending unit? You have a 0-90 range. 0 is empty tank, 90 is full. half is 45 ohm and 1/4 will be around 22 and so on. Do you know how much gas is in the tank currently? If the float is bad, the reading will always be 0 ohm because the float will hold the sending unit arm at empty.

If you do not have an ohm meter, I would suggest getting one or borrowing one. You will just be chasing your tail without it.
EDIT, sorry, I read above that you do have an ohm meter.

Let me know if you have any questions.

Take care,
Tom

[cjoenny89]

I will check the resister on the back of the gauge since I need to replace some bulbs on the gauge cluster anyway. I have all kinds of resistors at work and I think I do have a 100 ohm in my cabinet. I will check it out. In my hast to check to see if my wire had continuity by using the ohm meter I forgot to check to see what kid of ohm reading I was getting. I think there is about 10 to 12 gallons of gas in the tank.
how many gallon gas tank is the V8 tank behind the seat? I thought it was funny it is actually marked v8 on the tank

[BrianG]

The tanks are the same between the V8 and I6, however the sending unit is different.
Another check of the wire that you could do, would be to unhook it from both ends and check either end to ground. It should show open (infinite) and not a closed (zero or little to no resistance) reading. Maybe you already did this, I wasn't entirely sure by reading your original post.
The line coming out of the sending unit for the v8 is larger. I think v8 is a 3/8 line and the I6 is a 5/16 but don't hold me to those numbers.... By the way, hello, from a fellow mid-Michigander!

[cjoenny89]

Hello Brian I just spent a wonderful weekend at the Oakly old gas tractor show!
here is a picture of our truck we liver over near Marion springs on Merrill Road!
the other picture is the tractor show!

[cjoenny89]

I didn't take the wire off the sending unit but pulled it off the fuse block. I tried to get it off the unit but was having trouble with the seat being so close.
I touched one end to the fuse block end and when end to the lug where the wire was at the unit and it was "closed" it was also closed from the fuse block end to the tank. Is that suppose to be? I will try to get it off. I was basically just trying to make sure my wire wasn't broke or grounding out to the body but it looks like it is picking up off the tank anyway.
I made up a new 100ohm resistor for the fuel gauge if I need and I will check the out put from the sending unit. I can check the end from the fuse block and ground right while reading ohms? should read somewhere between 0-90ohms?
If not broken wire or bad sending unit. If it is reading between 0-90ohms then resistor on fuel gauge might be back and check it for 100 ohms?
do I have this correct so far?
Thanks

[BrianG]

I was at the Old Gas Tractor Show all Day Saturday. I live just a mile north of it. I can hear the p.a. sometimes along with some of the bigger tractors and the large motors in the large motor shed. Actually could smell them running Friday night.

I believe that a bad float and a shorted wire are going to both give you the same results at the gauge and with an ohm meter at the fuse block when checking the wire back to the tank. Both would show no ohms. So, if the resistor is okay at the gauge, then I think you'll have to pull the seat forward to get to the tank. If you end up having to do that, disconnect the wire from both the fuse block end and the tank end, then check resistance to ground. It should be open. If you don't get open, then you must have a short in that wire.