E30 Zone

Hi there,

Im having inaccuracies in my petrol level reading on the dash. When I turn on the car for the first time it will show the correct amount (say half a tank) and then whilst driving around for a while it will go right down. At first i thought i was getting really bad fuel consumption or a leak! but if i switch off the car for a while, and then go to switch it on again, it will have gone up.

It only annoys me because if im travelling a long distance and want to know when i have to fill up, its gonna throw it out of whack.

The the car went from germany to america and then over here, so its had its dash changed a few times, and possibly the fuel sensor is positioned wrongly etc?

Anyone got any ideas?

Need to know if it has a 55 litre (small pipe joining the two halves at the bottom) or 62 litre fuel tank (no interconnecting pipe).
There is a small brass nut on the back of the instrument cluster, behind the fuel gauge, that should be checked for tightness.

Sorry to Hijack but my question is kind of related. I have a 318is (1990), what was the standard tank size in that? My fuel indicator seems to do what it wants as well when I'm driving, goes right down if I give it the throttle a squeeze, then it may go back to normal later lol, but the other day when I thought I was almost empty, it barely took 41 litres (I thought it was 60, so I kept trying in vain to fill, ended up overflowing all over the forecourt)

Ok cool I will check those two things over the weekend. If not this, could it be a busted fuel gauge/sender which would have to be replaced? You say there are two senders (one on each side) so if one is busted, that would likely be the reason for the wrong reading?

My 318is my mate and I just changed the fuel tank on had a 55 litre tank

My iS had a 55l tank.

Funnily enough, after reading this thread, my fuel guage is doing the same (it was fine before)

HJG-E30 wrote:My 318is my mate and I just changed the fuel tank on had a 55 litre tank

All 318is's use the smaller 55l tank

If it's a 55 litre tank, this makes things a little more simple, as there's only one sender to consider.
If the brass nut on the back of the cluster doesn't help, pull up the rear seat cushion, remove the inspection cover, pull the three pin plug off of the fuel pump assembly, and use a piece of wire to short together the brown/green and brown wires. This should make the gauge read full.