Hello all,
Joined the site a few months ago with the intentions of doing an intro post when I had the time, but I have an emergency that has popped up and could really use some help. On Christmas Eve I was on a 2 hour drive away from home, and about an hour and a half into it my water pump bearing busted. Car got just barely to the red line temp wise, I pulled over shut it off and towed it home. About a week later turned on the car briefly to turn it around so I could replace the pump, car had a little trouble starting and didn't run very well. Replaced the water pump a few days later and when I went to turn it on.... nothing. Its turning over, every once in a while it will backfire, and no gas smell. I disconnected the line to the fuel filter and fuel came pouring out so I assume the pump is working and I can't see the filter getting suddenly clogged like that. Here's a list of everything that I even touched while replacing the water pump.
-dipstick
-idle control
-fan clutch, pulley and housing
-belt
-wire harness cover (frontmost 2 screws only unscrewed)
-tensioner
-ps pump
-water pump
-distributor cap
-a vacuum hose on the front of the intake manifold which the boot broke
-a vacuum hose that plugs into a Y shaped connector which just came unplugged. I securely plugged it back in.
-the sensor on the front of the crankshaft. I pulled on it a little when putting the new pump in and the wire is frayed. I don't know what to call this as I've read many different answers.

Does anybody have any suggestions as to what could be causing a no start situation? Tested wires and they are sparking. I am at wits end. Tryed starting for a good 30 minutes, pressing accelerator peddle and not and didn't catch at all, although I could feel it wanted to a couple times. I have a new distributor cap and rotor on the way along with a timing cover gasket, just to eliminate all that. Again, I'm new so apologies if I have posted this in the wrong section.

Thanks in advance,
Austin

 

Austin

Check the fuse(s) on the top of the OVP...doesn't matter what your VIN is as the OVP is the first place one looks if a M103-12V has starting problems.

Basics first, then on to the next step.

Ed A.

 

Ed, I bought 2 new 10a fuses and put them in the ovp relay, but no change. Is it safe to assume that its not the problem then? Or is there another way to test it?

Plutoe, The VIN is WDBEA30D8LB068707 if that helps at all.

Thanks for getting back to me.

 

WOW...
I learn something everyday on these forums...
So on the VIN you looked up, pin 30 of the OVP no longer supplies power to pin 30 of the FPR and then though the contact to FPR pin 87 and on to the two fuel pumps?

Explain the "KE Starting Circuit", because without the ignition signals from the EZL nothing happens.

 

Not an "ELZ"...it's an "EZL".......
You're the expert...you advise.

After all I just have owned the same M103-12V since 1988 when I bought it new...so what do I know ?
Even had a few of my older Mercs featured in magazines...guess I need to learn more about them...then I could be a genius like you and step up to owning a diesel wagon !
Thanks for the strong advice.

And did the WIS tell you the car will crank with a bad CPS, but not start and even misfire in trying to start...???

Why did you avoid answering about the OVP powering the FPR...
In case you were busy with DAS, I'll post it again:

"So on the VIN you looked up, pin 30 of the OVP no longer supplies power to pin 30 of the FPR and then through the contact to FPR pin 87 and on to the two fuel pumps?"

Does it or doesn't it

Good luck with the WIS and DAS..

 

Hey guys, wasn't trying to start a problem, although I do appreciate both of your interest!

Ed, you do have some nice Benzs. I read your widebody build thread a while back and I gotta say, your w124 is one of my all time favorites!

Plutoe, when I turn the key I definately hear the pump begin to prime. So I would think unless its malfuntioning somehow that the relay is okay too.

Again thanks!

 

Ed, Upon double checking the above comments I saw you mention the CPS. Is that located on the front of the engine on the crackshaft itself? Or back by the flywheel? That was what I first suspected may be wrong but when checking it out I could never get a straight answer as to the location, whether or not this car has a cam shaft sensor, so on and so forth.

 

You Have a M103-12V which unlike the M104-24V has no cam shaft position sensor.
Valve timing is fixed on the SOHC motor.

Unlike the M104 HFM the M103 has separate and not really connected CIS-E fuel control and EZL ignition control.
If you have fuel and hear the pumps the FPR should be fine.
The OVP can give some erratic problems if bad as it acts as a "gate keeper" to both fuel and ignition...sort of a bridge between the two among other duties.

Engine will always crank even without fuel or spark.
The cranking is a separate system that only depends on the starter.
The CPS gives a signal to the EZL and the OVP sends a signal to the FPR to energize the fuel pumps.
If the engine doesn't start and no speed signal is established the OVP drops out the FPR and de-energizes the fuel pumps.
No signal to the EZL and no start or try to start and misfire.

Below is the link on the CPS back by the flywheel.

http://www.benzworld.org/forums/atta...nt-15-2133.pdf

Ed A.

 

No problem with me...Pluto is giving me an education....
Probably much younger then him, I've only been involved with competition motor sports, engine building and concours restoration for fifty years...

Did you see the article in the November issue of the U.K. magazine "Mercedes Enthusiast"

 

Pluto

Why start a thread when I'm not "hijacking" but merely asking you to clarify the below comment you about the OP's situation:

And you said...

"I do not do any thing from memory or use the finger in the wind approach---I use the VIN to understand documented systems specific to your vehicle. In this case I was looking at the KE starting circuit and the OVP ain't apart of that circuit!!"

Why can't you answer and explain how the OVP has nothing to do with the KE system???
Without the OVP sending power to the FPR the fuel pumps would never energize and without fuel no sense having a CIS-E controller.

Do you ever wonder why this forum has been a barren wasteland...
I've been on here years before you and do know the protocol...
But again you have this desire to be correct...

And yes I am a satsfied Merc owner..been one for twenty six years and have a fairly nice collection of limited production and very special Mercs...probably have $300k worth with well over 2000HP of Mercs.
Alas I'm missing out on mundane diesels...
Oh well perhaps in my next life I'll become boring...

 

Alright, good to finaly have that cleared up. I went ahead and ordered a new CPS, should be here on Wednesday. I'll make sure to update as to whether or not this solves the problem. I also tried looking at the Nov. '13 article but the website mustve been down.

 

https://mbworld.org/forums/e-class-w...ody-build.html

 

Put in a new distributor cap, still not starting. Then this morning I put in the new crankshaft position sensor and it started up. For anybodys future reference, only took about 15 minutes to get the old one out and the new one in. I used a socket with a hex key, I forget the size but its the same as the bolts holding the distributor cap, a elbow joint, and a 12 inch extension. Screw came right up, reached in grabbed the old, snipped the wire near the sensor and pulled it out from the other end. Not harder than pulling a spark plug.

Ed, thanks for your help. Your car is immaculate... I noticed you have wood trim on the glovebox door, is this a certain wood trim package, or just on the coupe?

 

Austin

Success without your VIN, DAS, WIS or any other combination of letters...
Just common sense diagnosis if you understand the less then sophisticated and far from full electronic systems of the early 124's

The wood trim on the dash was actually a period aftermarket kit.
The standard 1988 300CE was rather plain inside...later models had a bit more wood trim...

Ed A.