Engine Performance problem
1985 BMW 518 4 cyl Two Wheel Drive Manual 160000 miles
Have had this problem for a number of years and it has progessively got worse. After 2-3 hours of continuious highway driving (100-130kph) the car would surge and then backfire and will not respond unless accelerator is down to the floor or nothing on it at all. It's almost as if there is a fuel blockage or shortage. Stopping for an hour or so and I can drive for another 40-60 minutes before the problem occurs again. Towing a horsetrailer or caravan and the problem occurs after an hour or so. Happens winter or summer. Under normal city driving there seems to be no problem.
Well, nothing actualyl, not being mechanically inclined. Have described the problem to various mechanics and they are dumbfounded. One suggested it was possibly water contamination in the fuel tank or carb and suggested carb spirit. Didn't help at all. Like I mentioned before; car drives OK except on longer highway trips or pulling a load, so if there was fuel contamination, then symptoms will appear in normal driving surely?
April, 27, 2009 AT 11:09 AM
In the 85 aged cars, there was some issues with the M-10 motors and the wiring harness shorting against the fuel rail as heat and age degrade the insulation and cause all kinds of symptoms. Inspect and let me know what you find.