Car won't start... again.

[MazterDizazter]

Alright so just two days ago I replaced a bad alternator in my '89 325i. That fixed my no-charging issue. I drove it around plenty between then and 2am this morning. When I went to start it again at noon, it just cranked and cranked and wouldn't fire up. Battery was fully charged.

I listened for the fuel pump but didn't hear it come on at all. Unless it's really quiet, I think that's the first place to start. I am waiting for my friend to give me my stethoscope back tonight so I can check the injectors, but for now I'd like to make sure the ignition system is in order. I have a multimeter but I've seldom used it. How can I check for spark? I tried putting a screwdriver in one of the spark plug boots to see if spark would jump from the screwdriver to the valve cover but I didn't see anything; perhaps the screwdriver or the valve cover weren't conductive enough but I'm not sure. I also looked at all the fuses and they seemed to be fine.

Any help is appreciated. This is my daily driver and I need it for school tomorrow so time is at a premium!

[Adrian_Visser]

it's an '89 right? check the cps and its wiring, check/ replace the main relay

[jlevie]

Pull a plug, connect it to its ignition wire, ground the body of the plug to the valve cover, and watch the gap while someone else cranks over the engine. If there's no spark there, check for spark at the coil output lead to rule out the possibility of a bad plug, ignition wire, or distributor. If you still don't have spark check to see if 12v is present at the + lug of the coil when the ignition is on. If still there is power at the coil check for power to the DME from the main relay on DME connector pin 37 and to the start input at DME pin pin 27. No power from the main relay with start input present could be a bad relay or bad fusible link.

If there is power to the DME and no spark, the CPS is probably the cause, but a failed DME is a possibility.

If you have spark, check to see if power is being supplied to the pump (pull up the back seat) when the engine is cranking. If power is presented to the pump the likely cause of not starting is a dead pump. If no power to the pump, the fuse or relay becomes the likely suspects.

[MazterDizazter]

How do I test the CPS and how do I pull up the backseat?

[xLibelle]

at front of seat cussion, wedge fingers under and yank up. it's spring clipped into place.

[slo325i]

If the car's crankin and crankin, it's not a battery or alternator issue. You may have replaced your good alternator for nothing...

[MazterDizazter]

Haha! Turns out it was a bad coil. I dug out the Accel Super Coil left over from my Z (Z is going to individual coil packs), hooked it up, and BAM! I now have a running car again. Although I can't imagine it doing any harm to the ignition system, I'll probably try to find a used stock coil to replace it with shortly.

If the car's crankin and crankin, it's not a battery or alternator issue. You may have replaced your good alternator for nothing...

This was a separate issue. The battery wasn't getting charged because the alternator was dead. I replaced the alternator (twice, because the first one Autozone sold me was no good) and that solved the issue.