Erratic fuel guage behavior at 1/4 tankfull.

[pundit]

I have noticed that once the fuel guage indicates 1/4 it seems to stay locked at that position for ages then suddenly drops to almost zero occasionally resulting in the low fuel indicator light illuminating. After stopping and restarting the engine the guage will then display 1/4 full again and appear to repeat the same process again two or three times over the next 20 kms (12 miles) or so until finally settling close to zero and the low fuel indicator comes on and then stays there until I refill the tank.

Is this a normal trait or do I have a sticky guage or fuel sender unit? My guess is either an overdamped fuel sender circuit or some kind of fuel tank baffling that effects the sender unit operation in this way at low tank levels - any ideas? Cheers.

[shogun]

This is from the E32, but it gives you some information how it works

click here (http://shrubbery.student.utwente.nl/johan/fuel_sender/fuel_sender.html)

[callen]

Great info....my 7's empty light comes intermittently at about a quarter tank....

Thanks

[pundit]

This is from the E32, but it gives you some information how it works

click here (http://shrubbery.student.utwente.nl/johan/fuel_sender/fuel_sender.html)
Thanks Shogun. These are the exact same symptoms I was talking about!
I'll look into it! ;)

[Paul in NZ]

hmm mine seems to sit on either a 1/4 or its empty...I thought it was normal.Most cars seem to be a bit erratic at low levels,i take a look too

[Am Piobaire]

mmm... mine does exactly the same thing also. Drove up to Brisbane for the new year (approx 800km) from where I live and had about 640 km on the clock and the gauge still read just under half - wasn't too sure how much petrol was there so I stopped and put in $30 worth (approx 28 litres). The gauge jumped up to about 3/4 so it wasn't too far out. The range doesn't seem to be too bad - (mine has an M20 donk). I let it get down below a 1/4 on the return trip. Driving along on a 1/4 then suddenly it plummeted to mt. Yikes! About 5 minutes later it jumped back to a 1/4. After that scare I pulled in at the next servo and filled her up.

Verdict? How to stop the gauge misbehaving? easy!! don't let the level drop below half a tank!!!

Andrew

[DanQ]

This explains why the computer always told me I had 50-70 more miles range when I fill up. I always trusted the fuel gauge before the computer when it should have been the other way around.
Looking in the manual I found that I really have a 21gallon tank vs the 17 that usually goes in on a fillup.

[Craig]

I tend to drive more by mileage than the gauge, I learned this after several years of driving cars with non-functional or questionable gauges. It's a good way to go, once you know about how many miles you typically get out of a gallon.

My gauge is a little weird but seems to be somewhat reliable so far.

[Am Piobaire]

Yes, I have spent years on motorbikes with no fuel gauges and you have to rely on the tripmeter - actually, its probably the most accurate method - you can usually predict when you hit reserve within + or - 10 km's.

Andrew