M8 Fuel Gauge Issues

[tonypearson]

HI

After a bit of advise on my fuel Gauge when its empty it shows full when its full it show half empty can anyone help


Thanks

[foofymonster]

Several possibilities Tony

1) it may be f****** they don't work, and stay working the best in my eperience, the float may be sticking too

2) it may not be eartherd properly if you have a rubber cell still in it

3) the short arm extension may be cathching - and gouging and destroying slowly on the rubber cell if you have one still in.

First thing to do is pop the armored cover off and pull the float moving it by hand and checking guage, trim short arm whilst you are at it. if it works, try an earth wirefrom gauge to vehicle body and put gauge back in and test it, obviously tank needs expensive fuel fill for this

[tonypearson]

HI

Thanks for the reply forgot to say i have the sender out already and have fully earthed it and moving it by hand so is free but just not seem to read correct do you think it could just be a faulty sender

Thanks

[j506]

Did you try to swap the gauge connections?

Hope this helps
john

[tonypearson]

i have and its just read full all the time then

[j506]

i have and its just read full all the time then

In that case i would suspect the sending unit is grounding itself
Do you have another to try either a gage or unit?

Hope this helps
john

[dlk]

The gauge is faulty. It functions as a variable resistor in the circuit. If you attach an ohmmeter to the sending unit you will see that the resistance does not change smoothly as you manipulate the float up and down.

[tonypearson]

Hi

Thanks for your help i have replaced the sender and now all good so just a faulty sender unit by the looks


Thanks

[John Neuenburg]

Tony, did you find an original sender or use something else? If the latter I'd like to publish the part number and source on the parts crossover chart that's posted on this forum. It's for any part number that replaces an original part, both new-made or old parts that were designed for other MVs but work for our cars.

In case anybody is interested, here is my sender, I assume an original:




There were two different sender numbers used, each with it's own gauge, with the change indicated by car serial number in the Ord Supply Catalog. Anybody know what the difference is and what happens if you use the wrong gauge for the sender?

[j506]

The early pn# is to long a will touch and chaff the rubber liner and we know whats next
the later number is supposed to prevent that problem
i made mine from an original bottom soldered onto an NOS top either from jeep pwered generator or a cckw 352 fuel tank i don't remember which
hope this helps
John

[John Neuenburg]

The early pn# is to long a will touch and chaff the rubber liner and we know whats next
the later number is supposed to prevent that problem
i made mine from an original bottom soldered onto an NOS top either from jeep pwered generator or a cckw 352 fuel tank i don't remember which
hope this helps
John

They must have different resistances that required different gauges, right?

Sounds like the part that fails is in the head. Good to know soldering doesn't screw it up.

[dlk]

Should be relatively easy to get to the resistor and repair/replace the windings since it is in the head. May not even have to pull it from the tank.

[j506]

No you have to pull it out
i cut the nos part off near the bottom where the float pivots and spliced on a portion of the original in an effortto lenghten the entire unit
I think the heat from soldering would damage the resister if you were to close
Hope this helps

John