My fuel is wrong, any ideas why?

wshawn · Post by **wshawn** » Sat Apr 12, 2008 12:24 pm

I have had to replace my sender unit as the wire in the last one broke so no fuel reading on the gauge.

I replaced it with one with the same part number (can't remember what at the moment but can find out) any way the gauge now works, sometimes. The times when it does work you can watch the needle go down as you drive and it reads empty within 75 miles! Other times it does not work at all

What do I need to check and how do I need to do it to work out where the fault lies? Once I can work out what is wrong I can then try and work out a solution, any help would be appreciate as one day I will forget to reset the tripometer when I fill up with fuel with the inevitable result of running out

raygreenwood · Post by **raygreenwood** » Sun Apr 13, 2008 3:12 pm

You first need to check the entire ground wire from the sensor and then the ground connector to the instrument cluster. It may also be that the float in teh sender unit is sinking. Take it out and check it fore leaks. Ray

Wally · Post by **Wally** » Mon Apr 14, 2008 9:52 am

Shaw, I hope you don't have the '74 model like I do, as those sensers ARE different and pure unobtainium...

I tried a model from a late beetle and bend the tabs (a lot!), but it was a mex/brazilian crap thing and didn't work either. I now have a rather decent used one from the car I salvaged, but the trembles with anything under half full. Makes sense to wear out there, since that is were it mostly is.

Sorry for the ramble..

wshawn · Post by **wshawn** » Mon Apr 14, 2008 9:56 am

Thanks Ray but it looks like another dead sender unit as I had reached a point where the only thing left to check today was the unit itself. Carfully dismantled it to find the wire has snapped about 2mm from the copper spring tensioner thingy at the top end of the unit.

Is this the sort of thing that can be resoldered seeing the break is so close to the anchorge point or is it a no go?

I had real problems sourcing this unit and am now wondering why it would be the second unit to have a broken internal resistance wire. Is it likely that it is something I have done? Would removing the sender unit wire to earth it against the bodywork whilst the ignition is on blown it like a fuse, if so I need to know so that I do not make the same mistake again.

Better to look stupid and ask the question instead of wrecking another sender unit.

With these senders being scarce in the UK, just like many other parts, could I substitute it with a unit from a bay window van. I know the units from the vans are about an inch shorter so when the float is at the bottom of the sender I would still have extra fuel in reserve BUT with this in mind could it be used to read full, just over 3/4s, just over half and just over 1/4 and empty etc.? Or is it a case (as I suspect) that the sender unit is calibrated to the gauge and would read to far out to be any use?

raygreenwood · Post by **raygreenwood** » Mon Apr 14, 2008 11:18 am

Those senders are scarce everywhere. I doubt it is you doing it. These senders are delicate as it is. I would bet that it was damaged in handling or laying around on a shelf. You could try to solder it. As long as you are very clean soldering...I has a high chance of working. Ray

wshawn · Post by **wshawn** » Mon Apr 14, 2008 12:23 pm

Cheers Ray

shall hand it to brother when I next see him as he is a dab hand with a soldering iron and see what happens.