needing fuel gauge

[mtn man]

Fuel Gage

I have a fuel gage that I will gladly sell to a Steel Soldiers memeber and I will even ship it for you...

Now as to how I got the gage... I thought mine was bad to following the test per the TM. So I went to my local cucv junkyard and picked one up... still nothing. Still showing way past full all the time...

What I found was following my complete removal of dash, instrument cluster housing replacement (had a broken tab...), replaced al the bulbs on the cluster, and cleaned and DE greased everything... I had somehow 'nicked' the printed circuit and lost continuity between the harness plug (pin #1 I think) and the fuel gage...

so the moral of the store is use your meter (all MV owers have one by law I think) and (with the cluster unpluged) see if you can trace continuity between the gage points of contact and their 'home' position on the plug.

FYI to fix this problem- I built a jumper wire from the gage contact (it was 1 on far Rt side) to the correct position on the wiring harness. Been rigged up like that for a while now... no problems as fuel gae works fine.

If you still need that gage PM me... it is great condition.

Hope this helps... I don't post alot but I work on 2 of these trucks a bunch.

 

[berrett]

I checked the ohms from the electrical clips to the black ground wire on the sending unit

WITH KEY OFF
left clip = 0 volts
right clip = 0 ohms
bottom clip = 0 ohms

WITH KEY ON
left clip = 14.45 volts
right clip = +4 ohms
bottom clip -6 ohms

Today i went to the junk yard and tried 4 different fuel gages 2 from gassers and 2 from diesels
No luck with any of them they all went straight to Empty.
Ordered sending unit from NAPPA will be in wednesday...Thanks for the replies

 

[hilber]

Mine stays on full all the time. I was told by previous owner that it was because of using bio diesel. Any ideas on that

 

[berrett]

Hmmm , only thing i can think of bio diesel causing that is gunking up the float arm causing it to stick in the Full position.
Unlikely i would think tho.

 

[berrett]

Well the new sending unit that i ordered from nappa was wrong.
1984 k30 driver side mount is not the correct one for the M-1028
Unless my tank is not original.
So i took a second look at my sending unit and found that there was gunk inside the box that the float arm goes into.
Clean it out with brake fluid and my gage works like it should.

 

[top_prop]

Hmmm , only thing i can think of bio diesel causing that is gunking up the float arm causing it to stick in the Full position.
Unlikely i would think tho.

Bio tends to float gunk off things and clean them... that said, if all you run is bio without any biocides in it, then stuff can grow in the bio fuel...

But running some bio here and there, or just mixing it up to 20% with petro diesel should only 'clean' a system of crud and deposits... typically this is recognized by having to change the fuel filters.

I've had fuel sender trouble in another 25+ yr old diesel that cleared itself up when bio shocked a few tanks of fuel and changed the filters...

 

[100acre]

gage on full

My gage is stuck on full with the key in or out. any ideas ?

 

[Warthog]

Have you looked in the TM? It has a troubleshooting section for this issue.

 

[Anubis8472]

Have you looked in the TM? It has a troubleshooting section for this issue.

Indeed it does, however it is a very basic guide that can give false conclusions.
When trying to diagnose mine the TM's info says my sending unit was bad.
Thankfully I was smarter then that and didn't go droping my tank. As it turns out my gauge was bad, even though it passes the TM's simple testing.

The gauge has 3 terminals one is power, one is ground, one is from the tank sending unit.
The sending unit sends a varying resistance to the gauge depending on the float level.
The chevy (1008/1009 etc.) gauges work on a range of 0 to 90 ohms.
0 ohms empty
90 ohms full
(fords work the opposite way)

I guestimated I had about 1/3 tank based on odometer.
The sender terminal at my gauge read 35.2 ohms.
The fuel gauge indicated less then 1/8 tank.

After filling the tank;
The sender terminal at the gauge read 95.0 ohms.
The fuel gauge indicated 1/3 tank.

My gauge was bad.
All the TM checks is a basic 'does the gauge move' with an input of 0 ohms to open. This does not 'test' the gauge, this only tells you if the gauge is completely dead. If the gauge is not 'completely dead' the TM tells you to assume the problem is elsewhere.

Check the sender ground first. Remove/clean/reinstall, it's easy. If you can reach it check for continuity between the sender body and ground.

If your gauge is reading 'full' all the time then either your gauge is bad, or more likely you have a bad connection to the sender/bad sender.
To test the sender properly disconnect the sender wire (there should be a plug not far from the tank) and test the sender wire for an ohms reading.
You should see a reading somewhere in the range of 0-90.

If you get an O.L. reading then the problem is either that wire from there to the sender, the sender ground, or the sender itself.

If you get a reading in the proper range, 0-90 give or take, add some fuel and check that the ohms reading goes up like it should.

The sender wire goes up the frame to the harness and into the big plug at the back of the gauge cluster. If it looks good as far as you can see, you'll need to remove the gauge cover. Once thats off you remove the clear plastic cover, then the black tin cover. Now there is just one bolt between the fuel and speedometer gauges. After removing that the fuel gauge simply pulls straight out.

Behind the gauge are three 'clamps' that grab the three terminals on the gauge.
Test these.

The top-left should give you batt volts.
The bottom should be ground.
The top-right should give you the sender ohms reading.

If everything reads good here then make sure the terminals/clamps are clean and making good contact. Pop the gauge back in, if it's still giving an improper reading then it's an internal gauge problem.

0 ohms -empty
90 ohms -full
45 ohms -1/2 tank
60 ohms -2/3 tank
etc.
The reading won't be exact, but it should be 'ballpark'

If you don't get proper readings here, but you did at the sender wire then there are a couple things to check on the back of the gauge cluster.
Pull it out. I think you need to disconnect the speedo cable.

Check for the proper ohms at the sender wire on that big long 18 wire plug.
Check also at the gauge 'clamp' on the backside.
The sender to gauge signal goes through the plastic printed circut, check that for continuity and solid contact. The ground as well.

(BTW your voltage readings should be taken with key on)

To test the gauge itself you would need to supply batt volts-ground-varying resistance to the proper terminals.

If you still can't locate the problem, carry an extra fuel can....

 

[cheiser666]

is it possible to run a new ground to the sending unit without dropping the tank or removing the bed? I seems impossible to remove the tank without removing the bed due to the fuel lines being routed overtop the frame.

 

[Zero_cool]

If you have really small hands you can reach the pink wire on the top...
To replace the ground you have to drop the tank , the ground wire is soldered on.
I drilled a small hole for the ground wire and attached it with a small bolt.
Dropping the tank is easier with the box off but not nessasry.
Drop the tank a little bit then you should have enough room to reach in there and remove the clamps.

 

[mtn man]

fuel gauge

The fuel gauge that I had has been sold, good luck to all those memeber who have fuel gauge problems