BMW 5-Series E34 (1987 - 1996) - 91 3.5 Won't start.

Honest John Back Room » Technical matters
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Sun 24 May 2009 05:47
91 3.5 Won't start. - gstilphen
So my '91 535i was running strong as always. I went to get new tires. while I was heading there, it stumbled twice, but small, just a single missed fire on each occasion which I attributed to the engine being cold and old, but still idled smooth and ran strong. I pulled up at the tire place, and went inside. They came out a few minutes later and it didnt want to start on the first try, which is wierd, then it started right up but idled a bit low(probably around 500rpm). They pulled it in, turned it off, and lifted it. they lifted it a bit off balance though. all pressure was on the back, the front was about 2 inches off the lift, but it was just one of those low lifts that brings the car up just high enough to do the wheels, so I didnt say much. Car wasnt teetering or anything. They put on new rubber. lower it, and it cranks right up. They back it out about 6 feet just past the bay doors and leave it idling, I get in and get ready to backup and it just sputters out. I try to crank again and no start. no spark, no fuel. Starter motor is turning engine over, there is plenty of power from battery, but just no start. I was supposed to be at my grandmothers funeral in an hour, but no such luck. So I started with the obvious.
-Battery-OK(brand new)
-Checked all Fuses-OK
-Checked Ignition coil(new MSD coil) plenty of spark.
-Checked Fuel pump-OK
-Checked Fuel Pump Relay. No ground, but when I jump ground to a nearby suspension bolt, fuel pump fires right up, so PUMP is OK.
-Relay told pump to turn on, so RELAY is OK
-Checked CrankShaft Position Sensor-not sure how to test, but also less than 6 months old and appears fine.
-Checked all connections and wires in both electronics boxes under hood,
-Checked all connections and wires under rear seat and in trunk.

After getting the car towed and getting a ride to the funeral, I dug a bit deeper and started replacing things. here is everything that is new:
-DME-NEW
-Crankshaft position sensor-NEW
-Main relay-NEW
-Fuel Pump Relay- NEW
-All fuses-NEW
-Ignition Coil-NEW
-Spark Plugs-NEW
-Fuel Pump-NEW
-Battery-NEW(and expensive. red top optima battery)

-Fuel Pump turns on when jumped from relay terminals 30 and 87 but still no start.
-Fuel Pump does not turn on without jumper.
-No Spark from coil.

So to me it seems like maybe the DME isnt powering up? Maybe a bad ground somewhere? Gonna check the grounds in the morning, its dark and raining out there now.

Any other ideas?

Edited by Pugugly on 24/05/2009 at 08:52

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Thu 28 May 2009 20:14
91 3.5 Won't start. - beamer boy
How did you get on since Sunday? No doubt you checked fuel was getting to the injectors, and there was a spark at the plugs? Basic I know, but often overlooked..
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