Intermittent start problems on my’90, 740, 16v. Start problem doesn’t seem to be related to temperature (engine or outside air) or how long the car has set-it just seems like sometimes it doesn’t get starting fuel. Sometimes after setting for 2 days it starts right up & sometimes it won’t start after setting 2 minutes. Get a 2-3-2 socket 2 fault code return in test mode 1 after a no-start event. Whenever car doesn’t start it will start immediately if I spray starter fluid in the air intake and then it will run fine at idle, acceleration and cruise. I took it to a mechanic and he replaced the in-tank fuel pump. After he replaced it, the car still had intermittent start problems, he disconnected the battery to reset the computer & it worked O.K. for several weeks. Replaced the FI relay, still intermittent no start. Checked engine RPM sensor and it seems O.K.- it returns a code 3-3-1 (socket 2), and 1-4-1 (socket 6) in test mode 2.
I had a no-start and swapped the Radio noise suppression relay with the aux. fan relay & the car started right up… thought I had solved the problem, but now the car is doing the same thing again.
It seems like, after a computer reset, it would work good for quite a while, then start acting up. Now the time before it doesn’t start after a reset seems to be much shorter. Not sure where to go next. Any suggestions? I’m thinking the cold start valve or temperature sensor, but not sure I have the tools to test them or know how. I haven’t checked the pulsing of the Fuel Injectors, but I’m sure they are not pulsing or the car would start. Could this be an “air” problem? When I disconnect the AMM lead the car runs rough/won’t start, so I assume it is O.K. Not sure about the Oxygen sensor or if it would cause such symptoms. Any help or suggestions appreciated.