1990 300CE No Start - PeachParts Mercedes-Benz Forum

kiwi_bloke_nz · #1 09-27-2010, 08:00 PM

Hi guys,

I have a 1990 300CE with a no start condition.

Previously it had been randomly not starting - mostly when hot. No pattern, it would just crank and crank - then when left for a while start.

It was driven home, and has sat for a few weeks, now it wont start, just cranks most of the time. Occasionally you get a blahhhhh sound from the throttle body.

Injectors are getting fuel under pressure - haven't checked pressure yet though.
Appears as though there is spark at the plugs.

I'm thinking it could the CPS - however if this was faulty would this mean there was no spark ?

Or a weak coil...

Could someone help out with the test specs so I can test the coil and CPS with a multi meter ?

pifcat2 · #2 09-28-2010, 02:34 AM

I'd check the ICM aka EZL on the drivers fender. Pricey replacement but a failure can give you a no start condition. Check voltage or try taping it a few times.

kiwi_bloke_nz · #3 10-03-2010, 09:05 PM

Check the voltage of what ? At the EZL? If so which pins ?

I have the specs for the CPS so Ill check that tonight.

All my sources tell me that if the EZL is dead you wont get spark, but I clearly am. And Fuel as well.

Gilly · #4 10-03-2010, 09:56 PM

This could be a bit tricky. IIRC this, at least in the US, is an M104 but with CIS-E injection. Given the circumstances of the failure, immediately I would think fuel pump relay. BUT again, I think this might not have one, isn't the fuel pump controlled by the MAS relay? Hmmmm. I have even replaced a few MAS relays but has been a while. Can you run a meter or test light to the fuel pumps? I know you say it has pressure but is it enough? Might be easier to just check for power to the pump instead of pressure.
Early 90s are just a bear for info, every year or 2 there were major changes.
Gilly

kiwi_bloke_nz · #5 10-04-2010, 03:25 PM

It has a 103 engine, and also has a fuel pump relay.

Pumps run when key is on, loosened an injector hose and get fuel spraying out at pressure.

What sort of current should the pump be drawing, is this relevant ?

david s poole · #6 10-04-2010, 03:38 PM

correct me if wrong but you have a 300ce with 103 engine and cis injection?

kiwi_bloke_nz · #7 10-04-2010, 08:33 PM

Yes correct.

It is a 300CE, M103 Engine with CIS injection- Registered in NZ in 1990 - So manufacture would probably be 1989. It is a New Zealand new model.

david s poole · #8 10-05-2010, 01:26 PM

you say the fuel pumps run so you should be able to push down the plate a little and hear the injectors spraying fuel?you should also be able to lay a spark plug on valve cover and crank engine to see if spark.

Gilly · #9 10-06-2010, 05:21 PM

Just back from vacation, a short 2 dayer.
What it sound like to me, (would be easy and free to check) is a broken driver (or bracket as it's also called)for the rotor. You would need to remove the ignition cap and see if the rotor is loose. I have seen this before where the bracket is broken, once in awhile it'll hook up and let the engine run, other times it will be so out of time that the engine won't even try to run. Really weird as you'd think there is NO way it'll run with that bracket broken.

Gilly

kiwi_bloke_nz · #10 10-07-2010, 04:31 PM

Thanks for your help guys - solved.

Gilly, you were very close.

Pulled the distributor off, and all looked fine - except for condensation.

Wiped clean, reinstalled, fired first time. Lots of smoke initially from extended cranking though, and starting fluid, etc, etc !!

Can anyone tell me if there is meant to be some kind of seal where the distributor mates to the front of the engine??

Just for kicks, tested the CPS - round about 850 Ohms cold.

Gilly · #11 10-07-2010, 07:23 PM

Yes, under the metal bracket that the rotor attaches to there should be a large round orange disc (made of some sort of plastic) with a lip around the edge, a rubber seal should be on the outside of that disc.

Found a pic online that I downloaded to my computer (got NO permission so shhhhhhh!). The light orange part os the part I am talking about, I BELIEVE it should have a rubber o-ring around the outside but now am not positiive.

Gilly · #12 10-08-2010, 07:55 AM

Yes, there is an o-ring:
http://img.eautopartscatalog.com/hires/W01331620367BOS.JPG?width=300&height=300

joshlowe · #13 03-23-2012, 03:45 AM

I know it's been a while. Had to setup another account as forgot password on old account.

But car has come out of storage and issue disappeared for a while. Now it seems to present its self in the following way.

Cold start great. Hot let cool down for an hour. No start. Cool to cold starts.

Not easily reproducible. happens once then won't happen for weeks.

Tested the cps again. 800 ohms cold. 960 ohms hot. Believe this is still in range.

When it does fail to start, it sounds like the timing is all wrong.

We will replace dist and rotor, and report back.