My 86 BMW 528e won't start


#1

I have fuel and ignition. This problem was intermittent for a long while. Then one day I was climbing a 20 degree bridge and it stalled. I let it coast over the top and it started again approximately at the same longitude going down the other side. The tank read 1/2 so I filled it. But the same thing happened on the way home with a full tank. This time it wouldn’t start for a while. I pulled over, jumped the fuel pump at the fuse box and it seemed to work. That was the last time the car was off my property. I didn’t trust it after that and when I tried to start it most of the time it would not. Not even sputter.



At one point I pulled the plugs, cleaned them and it started and ran fine long enough to give it a bath. I parked it for a few days and tried it again, no soap. I gave up on it and drove my truck for a while and searched for a mechanic who acted like they knew what to look for, without success. My experience in this town is they are more than happy to charge you for leaning over your fenders and shaking their heads.







Finally it’s been sitting for a couple years now and I bought a newer 530iA, which is somewhat disappointing considering it cost a hundred times more than the 528. I miss the 528. I’d like to get it running again.



I owned service garages when I was young an good-looking but now I’m old it’s tough to bend and crawl. So I need to focus on the most likely problems.







Fuel flows from the pump and the plugs fire. When this car starts it starts in one or two seconds, never cranked and cranked. I’m a little worried I’ll burn out the starter if I don’t get direction soon.







What do I need to fix it? I’m thinking of getting a running parts car and swapping parts till it starts. thanks


#2

Although fuel is flowing, you should check for sufficient fuel pressure. You might want to check compression too.


#3

Interesting that it stalled while going up an incline. Have you checked for a blockage at the fuel strainer at the gas tank outlet? I had a job where we found debris that would at times float over and block the strainer which caused a restricted flow and intermittent stalling. When the debris wasn’t on the strainer, fuel flows as it should. Check and clean the fuel tank.

Benzman


#4

Also, replace the infamous fuel pump fuse evin if it appears to be OK.


#5

It is common for folks to think that they have spark when they actually have an intermittent spark due to a rotted lead on their crank position sensor. What type of ignition trigger does an '86 have?

If you have fuel in the rail and spark, and intermittent running rules out cam timing problems, then the part you have not explored is signal to the injectors. Put a stethescope (i.e. a broom handle) on an injector and see if you can hear it clicking when you are cranking the car.

You say it started after cleaning the plugs. Were they black? Is it flooding out? Flooding is usually caused by 1) cold start circuit that is stuck on or has a bad temperature sensor, or 2) fuel pressure regulator that has failed and is leaking fuel up its vacuum line and into the intake manifold.