760 fuel gauge not working .....!

[ian (archive)]

running a 760 gle 1990.
The problem a none working fuel gauge, or intermitent one. Can anyone suggest a thorough test procedure to pin the fault down?

 

[Roy Bolton]

Hi Ian,
The models around 1988 were well known for having this problem. Don't know if the later ones were the same. The problem was with the fuel gauge. I had an 88 for many years and for about 5 years of it's life ran with the fuel gauge not working. I just filled the tank as and when necessary and noted the mileage with the trip mileometer. I tried many different ways to get the gauge working. To eliminate the in tank sender, the haynes manual gives a description and a value of resistors to put in series with the wiring of the fuel gauge circuit. ie. in place of the in tank fuel sensor. With thge resistors in circuit the gauge records 3 quarters full. I bought a fresh gauge for the car (difficult to get hold of except from main dealer and pricey) but that didn't cure it. The gauge connects with three pins at the back into the printed circuit. I think this is where the problem lies and that the answer is to tighten the connections between the pins and the pc board. I was going to try this but finally sold the car and bought an 850. - Roy

 

[ian (archive)]

hi roy
cheers for that ill give it a whirl.
The new girlfriend was messing up my odometer method so I didnt know where I was.Ill let you know how I got On cheers Ian

 

[Roy Bolton]

Well, I've heard of various methods but the 'odometer method' is a new one on me! This new girlfriend seems interesting, at least she will be when she get the hang of it!- Roy

 

[vinran1]

Had similar prob's with my 84 760 T, never fixed it. ( I know, BIG help)

But recently, I aquired an 89 780T, when I purchased it I noted to the seller (among many other items) the gage did not work.

Whereupon he gave the dash a short slap with his hand, right above the left side of the dash. Instantly, the gas guage sprang to life.

He said, "Oh yeah, common with this vintage".

I now do this every time I get into the carand start her up, and it always does the trick for mine.

So obviously, there is a connection issue in mine at the dash panel itself.

It will be an easy fix when I finally get the motivation to take it apart, maybe a scrub with contact cleaner/copper brush or whatever.

So look at that area, try giving the dash a little spank, see if that helps.

It's free, and may point you in the right direction quickly if it causes the guage to start working again.

 

[Roy Bolton]

Think this proves the point about the three pronged connection on the back of the fuel gauge itself into the printed circuit.The only problem is that the connection itself is too small to clean with anything other than very fine sandpaper but I expect this would tend to loosed the connection by making the prongs thinner. Also, when i took mine out the prongs were clean. Cotact cleaner wouldn't harm but I suspect a little surreptitious bending of the prons (not a lot) would tend to tighten the connection. - Roy

 

[Michael Pardee]

Think this proves the point about the three pronged connection on the back of the fuel gauge itself into the printed circuit.The only problem is that the connection itself is too small to clean with anything other than very fine sandpaper but I expect this would tend to loosed the connection by making the prongs thinner. Also, when i took mine out the prongs were clean. Cotact cleaner wouldn't harm but I suspect a little surreptitious bending of the prons (not a lot) would tend to tighten the connection. - Roy

My experience with connectors is that the problem is often that the female side spreads out and makes poor connection. I don't know what style this is, but I've had good luck with several types sliding a needle between each female contact leaf and the connector body. It isn't a permanent fix, but sometimes it is lasting enough.

A chemical called "Tweak" sold at audio shops is the best contact enhancer I know. It is a diluted version of the shockingly expensive Stabilant 22a.

Mike

 

[Roy Bolton]

The connectors on the gauge are basically just 3 pins on the gauge which fit into 3 holes on the printed circuit. Nothing more sophisticated than that. You can't even use solder to provide a permanent fix as the printed circuit is made of plastic. - Roy