My 2000 323i (122,000 miles) recently experienced terrible hesitation while at highway speed until car slowed, stopped, and had to have it towed. Garage replaced fuel pump and then it ran great. About two weeks later I was down to 1/4 tank and bad hesitation started again. Really bad when starting from a light. Until I got into a gas station and filled up. Then it ran fine and has done so since. Took it to the dealer, who found cyl 5 misfire code. All spark plugs were replaced a year ago, along with coils 4 & 5. Anyway, can't believe one misfiring cylinder would cause the major hesitation I experienced. Misfire code can apparently be caused by low fuel pressure. Anyway, yesterday I replaced remaining coils. With full tank, have not had a repeat. Any suggestions? Could the new fuel pump be intermittently bad? Or is there a possible problem with evaporative control system or fuel pump control module? Anybody seen anything like this? Many Thanks, Robert
Misfires depending on how bad they are can cause a hesitation. Filling the tank makes the issue go away makes me wonder if your having a suction jet pump issue. Basically meaning the fuel on the driver side isn't getting transferred to the pump thus when the fuel gets low like quarter tank the fuel runs out for the pump even though there is quarter tank on the gauge.
Thanks much, I will check that. Also wondering if it could be as simple as a badly calibrated fuel gauge?
The fuel gauge does not have a calibration. It uses a variable resistor that as the float goes up and down changes the resistance which changes the gauge.
