733I that has been sitting a while.
 

Have a 1984 733i that was running fine when I parked it but unfortunately got pushed to the back of my project list. Now after a couple of years I have a new found interest in fixing it up but it will not start. Engine turns over fine but doesnt fire at all. What are some things I should look for and things i should do for a car that has been sitting for a while. Any suggestions are appreciated.

Presuming it has a coil and the 'distributor' on the front of the cam: check for spark. If no spark: check crank position sensors in the bell housing for coil continuity. If they are ok pull off the wire from the ign key to starter and then get a friend to hold the key in the start position (engine will not be cranking). Get under the rear of the car and listen for the one (or poss two fuel) pumps to be running.
Flush the stale petrol (gas) out, replace fuel filter and put 5 gallons in. Then the fun starts....... All the rubber under the bonnet (sorry hood), new battery, check test battery cables, check test alternator, consider tyre replacement - oh the list goes on......................

bimmerfan
 

I have restored and driven 3 of these E23's over the years. One of them I had purchase wouldn't start the day I bought it. After spending hours trying everything, it turned out that someone had dis-connected the two crank sensor cables that run from the engine down to the transmission. We connected them, and it started right up. It ran, but it was very rough. Over the following weeks and after much testing and phone calling, I found that someone had also put the wrong Motronic unit in it. This is the computer that makes the car run. They had put a 733i computer in my 735i. Because I had my other 735, I swapped out the computers temporarily, and found the problem. I now have an extra Motronic unit for a 733, if anyone is interested.