Mercedes-Benz Forum banner

87 420SEL Wont Start

2566 Views 5 Replies 5 Participants Last post by  Benzical
Need some help.
For some time the car has idled rough.
Recently getting very hard to start.
When it does start, it dies as soon as it goes into gear, recranks pretty easy, keep revs up and I can get down the road.
Checked cold start valve, it sprays.
By-pass air valve, cleaned, seems to function. Disconnect and idle goes up to 2000rpm.
To get home last Friday had to disconnect it to get it to crank and got home.
Due to other projects, it sat till Mon morning and it won't start.
I can smell gas after cranking on it a bit, also poored gas down the throat, no change.
It seems to crank over faster, but only seems to hit on a couple of cylinders when I let off the key.
Checked for spark, pulled plug and grounded it, spark seemed good.
Tried to adjust timing with someone cranking, didn't find a point where it seemed like it was firing better, rotated about 5deg back and forth.
Anyway, I think it may have jumped timing. (194K miles)
Is there an easy way to check?
What jumps first, left bank, right bank or distributor?
Also, I can hear the fuel pump running when I am trying to crank it.
Spark, check.
Gas, I think so.
Air, check.
Timing, don't know.
Compression, I think so, no reason for it to change suddenly.
1 - 1 of 6 Posts
Had the exact same problem, ended up changing the eight injectors, check valves ($800), plugs, distributor cap (read, not the rotor), OVP relay, feul pump relay,checked cold start injector, these were all for the hard start which did not fix, then one day car dies, after idling rough for a couple of days. SO I check ignition, but in my case there was no spark, I though it was the ignition control module, but checked the resistances and everything in the ignition system and everything was fine, eventually my mechanic said to change the rotor (since it was the cheepest thing on the list of things I was wanting to change) and whola! fired right up. The hard start problem persists, but I am going to change the cold start injector anyways, since it may be fine on a bench test but maybe it throws in too much fuel? Who knows!

Good luck and let us know if you fix the hard start issue.

Cheers
Sohaib
See less See more
1 - 1 of 6 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top