High Resistance at Fuel Sender

Cougar Community Classic Cougar Maintenance Restoration and Repair
1

I had an issue with low fuel level readings for a while. Just measured the resistance at the fuel sender and it is reading 120ohm with the tank approx 3/4 full (guess it should be around 25-30)

Would the high resistance be coming from poor grounding of the tank or do I have a bad (2 year old repro) sender?

Thanks

2

Did the fuel gauge ever read correct with the new sending unit? If not, I’d suspect the sending unit. Is so, then the grounds would be the next place to look, as well as any connections along the way. If you can measure resistance from the sending unit connector to the gauge, that should be 1 ohm or less.

3

Thanks. I was running a gauge level converter before for a digital bar graph gauge. Not sure if it ever read correctly.

Been testing all day and it looks like the new gauge I installed works OK. Amazing how many used senders I tried were rubbish and made me think the gauge was no good. Finally ripped a resister out of another sender and tested the gauge.

I’ll tackle sender wiring tomorrow but I’m leaning towards a dud sender

4

The maximum resistance from the sender is 73 ohms. I woul look for a high resistance connection in the harness

5

Ended up being a bad ground between sender and tank.

  • drained the tank,
  • removed the sender,
  • tested sender using a jumper to the gauge ( sender and gauge worked)
  • tested sender using stock wiring and jumper to ground ( sender and gauge worked)
  • re-installed it all
  • added petrol back into tank
  • sender and gauge working

Lessons learned

  • unleaded gas tastes like crap
  • make sure you have more than 60 litres of storage available if the tank is full
  • make sure the parts supplier has 20l jerry cans in stock before trying to buy one
  • send nasti-gram to parts supplier whose online system said they had 20l cans in stock when they didn’t
  • move to Phoenix so Bill can sort these issues out next time
  • prayer helps when working on electrics, throwing old sender when still attached to multi-meter doesn’t
6

I have been watching a lot of Australian TV shows… Escape to the country… Looks pretty good to me. I could come there.

7

Lots of advantages to living in the Phoenix/Tucson areas!

Sorry…I couldn’t “resist”.