1989 300E Intermittent start/run problem. - PeachParts Mercedes-Benz Forum

cjlipps · #1 10-13-2006, 04:24 PM

Just purchased car. 260K miles. Test drive (10-12 miles) did fine. Seller warned that car didn't always start. Started and ran fine when I picked it up from seller a few days later. Parked for a few days and it started fine when I drove it to go wash it. However, when I tried to accelerate quickly from stop into traffic, it stumbled horribly and nearly died. Was able to keep it running (or it kept itself running is more like it) but not running well. Died at stoplight but restarted. Died at carwash and did not restart (and I didn't wash under the hood). Called sister for a tow and by the time she arrived and we went to my shop to get the tow strap and came back (30 min) the car restarted and ran fine for the 2 miles back home. Today it started instantly and ran fine while I backed it out into the sunshine to check things out. I even let it idle a few minutes to see what would happen. OVP is fine (known good from other car), ICV hoses appeared ok, plugs looked good, no obvious vacuum problems... After reassembly of air box it wouldn't start! It acted like it wanted to run a bit when I released the key one time but it was nothing more than a horrid stumble for maybe 5 seconds. I gave it a little snort of starting fluid and it didn't change anything. This leads me to think it's ignition related. What could cause this? Does the coil fail like this at times? Crank position sensor? Or am I going the wrong direction? Temps here in balmy Oklahoma have been from 70 to 85 when working on the car and it doesn't seem to matter if the car is warmed up or stone cold, it does as it pleases. Thanks to all for all the help on my other car. Hope to get this one fixed as well.

MattBelliveau · #2 10-13-2006, 04:59 PM

Do a search for the fuel pump relay.

A264172 · #3 10-13-2006, 06:45 PM

Try starting it in neutral when it wont. ~to rule out Neutral Saftey Switch~

Try unplugging the O² sensor (under the passenger carpet and floor pad - one green wire) when it wont also. ~to rule out O² sensor~

also:
post when it dosen't start what does it do... turn over? just a click? ...

Moneypit SEL · #4 10-14-2006, 01:41 AM

Quote:

Originally Posted by A264172

Try starting it in neutral when it wont. ~to rule out Neutral Saftey Switch~

Try unplugging the O² sensor (under the passenger carpet and floor pad - one green wire) when it wont also. ~to rule out O² sensor~

The original post describes a crank-but-no-start condition. Why would the neutral switch or oxygen sensor address this?

cjlipps · #5 10-14-2006, 02:00 AM

Sorry, that wasn't clear in the post. It cranks very well at all times but sometimes won't start. And, not to sound cynical since I sure don't know the particulars of this car, but since it does crank, can we rule out the
N-safety switch? Also, the O2 sensor part doesn't make sense to me. The ones I've seen go bad (on American cars) won't keep it from starting but will make it run poorly once started. But, I'm not well-versed on the Benz so I'm sure gonna listen (gratefully) to any suggestions.
Thanx, Chuck.