M50 525 no start story - its my story and I'm sticking to it!

[Bimmer Nut Ed]

Anyway, daughter calls and tells me her 525 won't start. K, I come home try it, turns over, but nothing. Has a weird hesitation like it thought for a second to start, but really, no firing of any cylinders.

Hmm, now I've been with these cars a while, so naturally I think to check fuses, and I jump the fuel pump relay to hear the fuel flow up front into the engine compartment, and this all seems fine.

Hmm, without doing anything much else, I simply asume it's the crank position sensor. After all I remember when it went out on my m30 535, it had that same exact little hesitation when trying to start. Eh, it's old enough, prolly could use a new one anyway. So I order one, wait a week, and today I install it.

Darn thing won't start, same sounds, same old everything. wtf now

OK, check the fusable link, see that it fine, but I jiggle the hot wire its on and notice that it's loose on the battery. The post is all clean, only needs a little tighhtening. So I tighten it and the darn car still won't start.

OK, we've been trying to start this car for about two weeks now. I try to start it one last time before checking fuel line pressure and pulling plugs/coils to check for spark. I decide to pump the gas pedal and now I notice it actually fires a couple times. Still no start though. I try again, pump the pedal like mad, and she's starting to go! Holy cow, whats with this! It's still not running nicely, it's trying to stall, but I keep up the pumping and get her to run OK at about 2-3k RPM. I hold it there till it warms a bit, let her come back down to idle, and everythign is fine! wtf, what did I fix, was it flooded or something to begin with, was it the loose wire on the battery terminal, was it actually the CPS. It all seems so weird, it's like I'll never know what it actually was.

BTW, I did try new main relays and fuel pump relays with no success. Right now it actually has the original relays back installed.

Anyway, no big deal, this is really just an observation. I don't need help. Just thought I'd share.

Happy new year guys!

[Dave M]

Mine has been doing similar things lately. I don't drive it in the winter so I have time to fart around. Occasionally it doesn't want to start. I've replaced just about every sensor i can think of (not the CPS mind you) with no luck. I've tested the batt, alternator, fuel pressure (50+ PSI), but it could still be intermitent. I've even purchased a used DME, but it happens to run rough with the new one (as though a cylinder is not firing). The odd thing is, sometimes it will just start fine. Odd I say, odd......

Anyhow, glad you've got it going. Hope it continues to run for you,

Dave M

[Bimmer Nut Ed]

Cars can be funny, eh. Wish you luck as well. Maybe do try the CPS. My original CPS had major grime on it's head. Not sure if that would cause the problem. You're welcome to try my old one, lol!

500km on your E34, very nice. The daughters 525 has high miles also, 215k miles. She takes it off to college, so I hope she'll not have problems when she's away. Thinking about having her take one of the other bimmers just to make sure.

Anyway, luck to ya. Thanks for the reply.

500,000 Kilometre(s) = 310,685.596118667 Mile(s)

[Johntee540]

Very Odd post - I have been experiencing the same symptoms. They are very intermittent. And don't laugh but they are worse and more frequent when the car is pointed uphill than they are when pointed down hill. I am thinking Fuel Pump / Fuel Filter? -JT

[Jr ///M5]

Same thing happened to me with the 318iS....no start condition. I thought I could hear the fuel pump buzz. Checked the spark, etc, etc. Then I pulled the rear seat out to check the pump. What I found under the inspection plate was the plastic clip that holds the power connector plug to the pump was broken and had vibrated loose. I pushed it back on and a couple of zip ties later, it's been fine since.

Now that some of these cars are approaching 18 years old, I shudder every time I have to manipulate any plastic part on it for fear it's going to crumble in my hands.

[ryan roopnarine]

well it looks like you found the flood clear mode that pretty much any modern FI car has. even if flooding is not your real problem, you know what to try first if, heaven forbid, it happens again.

[karmann]

mine started the same way and gradualy got worse to the point where it would not stat at all .after changing the cps twice, and alot of other things (see my previous post) I still have to drive with the darn cps unplugged.
but I think its finaly cost me my cat now.

[Jon K]

Ed - having to open the throttle body to start the car sounds like the idle control valve may be sticking shut/dirty/clogged. Pull the ICV out and clean it and let us know.

[Bimmer Nut Ed]

Idle's great, but I hear you. I took a look, and that darn thing, I can't even see it. I see where it's supposed to be, but darn it, am I looking right past it, I can't even find it. Suposed to be right there under the manifold.
http://realoem.com/bmw/showparts.do?...91&hg=13&fg=15
and http://realoem.com/bmw/showparts.do?...81&hg=13&fg=15
Oh well, thanks for the advise, I will look at it if I encounter the problem again. I'm driving the car this week just to see how it acts and to determine if I trust it. Any additional symtoms, and I'm digging for that bugger to clean it! Thanks again Jon.

[BillionPa]

sounds to me like the ICV was stuck shut and needed some air forcing through it to keep it open.