Dohn
Well-Known Member
Have a stumper for the brain trust. My coupe has a 3.5 engine from an '87 735. A few months ago I experienced a severe engine stumble when getting on the highway, followed by backfiring and finally stalling out. Flatbedded to the shop, they diagnosed it as dead alternator and rebuilt mine. Also had to replace the depleted battery, as it would not take a charge. All was well for a few months, then I started it one day and it wouldn't hold an idle. Found a seized idle air screw and a faulty MAF sensor, which was replaced with a used one. The car ran fine. Then a month or so later, my fuel tank, which was dented when I bought the car, began to leak (on a trip to the BMW CCA Foundation). Once back home, I ordered a new tank and had it installed. On my next trip on the highway, when I decelerated off the highway and stopped, I heard a boom from the tank like you hit it with a padded stick. A glance at the tank showed a large concave dent in the bottom, apparently caused by suction. After asking on the forum, the suggestion was to check the vent tube, which we did, and discovered the vent tube on the new tank was clogged with paint. Cleaned it out, pressurized the tank to pop out the dent, and all seemed fine. Drove it to Mid-Ohio on Sunday, and as I left the highway and came to an intersection, it nearly stalled, then stumbled much like it had done before the alternator replacement. I was able to get up to speed, as long as I didn't try to do it quickly, but I could still induce a little stumble by accelerating from my cruising speed. Tank is once again booming, and the dent is back. Car is back at shop, and they are checking the vent tube all the way to the front.
Do all these things seem related, or have I just been having a run of bad (read expensive) luck? I was planning to drive this to the Genesis closing, but the chances seem fairly slim at the moment.
Do all these things seem related, or have I just been having a run of bad (read expensive) luck? I was planning to drive this to the Genesis closing, but the chances seem fairly slim at the moment.