1986 930 Stalling

While driving down the highway, my 1986 930 stalled. I was not accelerating at the time. It happened twice within 5 minutes and I was able to start back up while coasting by pumping the gas pedal. No burping/farting/backfire; the engine just died out. A friend was following behind and said blue flame shot out of my tailpipe (it was night) My mechanic has not been able to diagnose the problem. The car ran fine before and now. I did add octane booster in he previous fill-up, as I do about every 3-4 tanks. Any suggestions?

Our 1987 had this problem and I traced it to a fuse that was wearing out. Check the back (aft) two RED relays on the main fuse/relay panel in the trunk, check all fuse screws to make sure they are tight and remove the last several fuses and if they look worn, replace them. Turbos have two fuel pumps and if one fails it may keep running, but is unlikely. Also check the run-on relay (tall yellow) in the relay panel in engine compartment to make sure it is okay. Note DO NOT put black relays in place of red replays, but you can switch red ones around. I would stop using octane booster, Chevron 92 octane should work fine and is what we use and ours is very modified. Most other Turbo owners I know in SoCal fell the same. If I race I mix 50-50 with VP103 race gas to be safe. Thanks to John at Black Forest, Good luck.

Thanks for the info John. My mechanic says he thinks the fuel pumps may need to be replaced. He says they are making a whining noise (similar to my wife when the car is in for repairs???) and will check them out on an oscilliscope. If they are not so bad, I am inclined to change out the relays per your suggestion and see how the car runs instead of investing in new fuel pumps. If I have to spring for new pump(s), how are the rebuilt ones for reliability/performance. Do the fuel pumps in fact have a high failure rate? Any input appreciated.

Our 1987 Turbo has 98k miles on it and the pumps are the original ones. Driving it seems to help keep the gas flushed through them and using a good brand of gas (Chevron) seem to help also. I also put a can of Techron in every few months. If they are going bad, I would replace both at the same time.

A further update on my stalling problem. I have brought the car to a new shop - Zims Autotechnik. They have isolated the problem as ignition, and not as fuel. It has been hard to diagnose since the stalling does not happen on a regular basis, but seems to be when the engine gets hot initially. One by one, we have added a new run-on relay (tall yellow), a new Permatune unit (I did feel better performance with this unit), and a new coil. Problem not fixed. They say they checked the ground straps. Car still stalled out after about 10 miles. Next step is a new relay (the oblong silver one in the engine compt) and finally rebuilding the distributor coil wiring. We have been at it for about 2 weeks now. Any further ideas/input would be appreciated.

The shop I deal with said to also check the alarm system, especially if it is a Clifford or one that disables the car. They can cause intermittent stoping, etc. Ours had a problem with the fuel pumps not running, but would start after a 30 sec delay? Our Clifford alarm has a 30 sec delay before auto arming, the only thing on the car with a 30 sec function. I unhooked the alarm and the problem went away. Try removing the alarm if you have one and see what happens?

The problem ended up being the Permatune unit. What caused all the confusion is that they replaced the unit with a new Permatune that was defective! Apparently the Permatune units are prone to heat damage - driving a black/black 930 here in Dallas when we had 24 straight days over 100 degrees is a real test on these units.