90' 525i cranks...won't start...HELP!!!! - BMW Forum - BimmerWerkz.com

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post #1 of 3 (permalink) Old 03-25-2008, 01:56 PM Thread Starter
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90' 525i cranks...won't start...HELP!!!!

My brother has been helping me with my dilemma and I'll just paste his post from another forum. I need as many opinions as possible and would appreciate any suggestions. Thank you.

Hello everyone. I am trying to help my brother get his 1990 BMW 525i (manual transmission) running, but we are kind of at a stand still. I was hoping to get some help. I went to school for electrical engineering and have been working in the mobile audio/security industry for 7 years, so I know my way around electrical things, I just need to know what to test.

Here's how the story goes. The car ran fine and then sat for two days. When he went to go use it, it wouldn't start. The car then sat for about 7 months or so because he had other transportation. I started looking at it with him a few days ago.

Here's a summary of the car. The car cranks. The battery is good. The fusible link was blown for a while before this happened, but it is fixed now. We couldn't do the "stomp test" because the check engine light wasn't coming on even though the bulb was good. I tracked that down to the main electronics relay (the white one) which was bad, so it was replaced. We did the stomp test now, but it reads no faults (1444). Occasionally, the oil pressure sensor/switch light message comes up on the dash, so he replaced that because it was cheap, but it still comes up. The wire doesn't look too healthy, but I can change that later. I don't think that would cause the car not to start.. but tell me if I'm wrong.

The fuel pump relay is not being turned on. If I manually energize the relay, it will turn on, but the car still doesn't start. We can hear the fuel pump working in the back when I power up the relay too. It is just not getting signal from the computer or something to turn it on normally.

I tried testing the coil, but I don't know what it is supposed to read. The coil has the wire that goes to the distributor, a wire labeled +, and one labeled -. I assumed the + would be 12v ignition and the - would be ground. When I meter them, I get 12v on both wires when the ignition is turned on. I pulled the wires off and the + and - terminals read continuity with each other inside the coil. Is that normal? Is it pulling a ground from somewhere else to turn it on? I didn't do the test where I take a spark plug out and test for spark that way yet.

Even if it wasn't getting spark though, the fuel pump relay still isn't turning on.

A mechanic who used to own this car did look at it and said the crank sensor was good, but I don't really trust him. I'm positive he has zero electrical skills, but he may have switched the sensor out with a new one temporarily to try it. I don't know for sure. It would throw a code if the sensor was bad right?

So I am wondering where I should go from here. I'm hoping it's not a computer problem. He doesn't have a lot of money to be swapping parts out to see if they work. Thanks for any help!!

Last edited by urai4m; 03-25-2008 at 02:01 PM. Reason: mistake
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post #2 of 3 (permalink) Old 03-25-2008, 02:21 PM
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I posted this over on bimmerforums, but here goes, download this Bentley_BMW_5-Series_Service_Manual.pdf . It's the best, most expensive repair manual for these cars, and you can have it free.

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post #3 of 3 (permalink) Old 05-07-2008, 01:28 PM
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I really need this Manual to work on 88 M5 no start. Is there any trick to getting a dnload of it.
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