M116 won't start

[mathew]

Ok gang I replaced the fuel injectors in my old 420SEL and the difference was amazing but it ran a little rich. So I replaced the coolant sensor and problem was fixed or so I thought.

The car just stopped at an intersection no stumble, no sign of anything wrong just stopped.

Here is what has been replaced this year:

Disy Cap
Rotor button
HT Leads
Plugs
Fuel pressure regulator
Fuel filter
Fuel Pumps
Fuel injectors
EHA Valve
OVP relay
Oxygen Sensor

Last year fuel pump relay and ignition coil.

Symptoms are I have excellent spray from fuel injectors, I have spark at the plugs yet it won't start. Turns over on the starter motor spot on but alas she just won't fire. Timing chain all good and swapped out an EZL module to rule that out to no avail.

Any ideas I thought if the crank sensor packed it up I wouldn't get spark am I right with this assertion?

Cheers Mat

PS even if you pour a cap full of fuel down the butterfly she still won't start not even a splutter could the spark simple not be strong enough how do i test that?

So anyone hazard a guess

 

[260ebenz]

Message sent Mat.

 

[SEL_69L]

I would carefully check the installation of each of the items recently replaced.

 

[mathew]

Sadly I have checked everything three times and everything is coming up good any suggestions?

 

[abl567]

The gov is having a hissy fit due to the latest "storm"

 

[mathew]

LOL well if he is he must be telepathic, because he played up before Storm was even considered and it was his bad behavior that drove me to a new car. One's daily driver must be able to deliver first time every time and for some reason, the Gov has decided a midlife crisis is on the cards. Non the less I luv him so and won't be parting with him but it would be nice to take him out on weekend every now and then.

 

[260ebenz]

Hey Mat sounds like Governor is suffering from "W126 Battleship blues".

I should not have said that there goes the spin in the C-Class in September! LOL.


Might be time to part with the beloved "Gov", hey Mat why not consider another W124 Mercedes just an idea?

No hard feelings towards "Gov", I know him well and he is a very loyal serving "Battleship".

Cheers.

 

[mathew]

Ok guys the old boy still won't start, the following has proven serviceable or been replaced new.

-Disycap & rotor button
-Plugs
-Fuel pressure regulator
-All and I mean all vacuum lines and rubber hoses
-Fuel injectors
-EHA valve
-Ignition coil
-HT leads
-EZL module
-Fuel pressure regulator
-OVP relay
-Fuel pumps
-Accumulator
-Coolant Temp Sensor
-Fuel Pump relay
-Crank Angle sensor

Needless to say had I not had a good contact when it comes to parts I'd be out of pocket wads of dollars. The timing is spot on so what the hell could it be and yes i have compression.

Now out of sheer anger I think I decided to pull the airflow metre and fuel disy off and I found fuel inside the assembly of the airflow metre housing. Now I know M116/7's will never start with excess fuel so my question is can the fuel distributor leak fuel underneath into the airflow metre housing. Now I can't see how it could, unless it was leaking from the centre pin that contacts the butterfly arm. So I'm thinking i have a rich start problem and it's got to do with fuel getting into the airflow metre housing can a fuel distributor do this?

Before the car just stopped it was blowing black smoke on start up (too rich) but once closed circuit it would run fine I guess because the computer was leaning it back to compensate. Yes I have spark and it cranks over fine but no fire so to speak. I've asked every where and it seems to have everyone stumped so can a dud fuel distributor flood the engine on start up?

Cheers Mat.

 

[Oversize]

Are the plugs wet??? Try starting on full throttle..... Does it have a cold start injector? Try disconnecting that...

 

[260ebenz]

Hi Mat sorry to hear Gov is still not starting almost 3 weeks now how frustrating!

Sounds like you have replaced just about every part in the 420SEL and still getting know where.

Contact Perry Penfold in Newcastle I have sent you Perry's phone number before if you don't have it let me know.

Perry will solve the problem with Governor just ask Perry he is brilliant with Mercedes and he is very good with the W126 S-Class.

Hope this helps mate and please keep us posted with your progress.

Cheers mate,
Tim.

 

[Styria]

Matt, I didn't realize that you are still having problems with your 420. I hadn't followed the thread until this morning. I experienced similar problems with a 450SEL just recently. The car ran "fine" until it got to my home. Then one day, it was reluctant to keep running "when putting foot on brake prior to engaging drive", and it would do so several times - in fact the motor would stall. A similar situation developed "when engaging gear without foot on brake" and initially, in the end, it would not start at all.

Eventually, after about ten minutes, she fired, I "shoved the car into drive" and just managed to get the car into the driveway, but after that it just refused to start.

Eventually, after several days of non-action due to rain, I started checking components. There was spark everywhere (good), and fuel pressure seemed fine - I disconnected the plug to the fuel valve (I think that's what it is called) just to the right side of the fuel distributor to obtain a constant flow of petrol, turned on the ignition and loosened the fuel supply line to the fuel distributor - with plenty of fuel spurting out. Pushing down on the fuel flap seemed to indicate that there was fuel pressure, especially with the ignition "ON" and the electrical plug disconnected. Howver, once I reconnected the electrical plug, there would be pressure evident only in the fuel flap for about two or three pushes, after that "nothing" and also, when pushing it down several times with ignition "ON" and electrical plug disconnected, the injectors did not seem to respond to "careful" listening - normally, you can hear a bit of a "hiss". That wasn't evident.

In the end, Matt, I shifted my attention to under the car. With ignition on and plug disconnected, the fuel pump made some strange, intermittent noises and, just to be sure, I poured twenty liters of petrol into the tank, with no improvement, but when a tipped a small quantity of petrol down the air slide (flap), the car would momentarily fire up. So it was definitely a fuel problem. I replaced the pump, and as a good measure the fuel filter as well, and the problem was solved.

In your case, I am sure you have tried all that. Howvever, you have small twin fuel pumps. Are they both working - sometimes after market items can be faulty, or not last as long. Do you get the "hissing" of the injectors when you push down the flap ? Is the filter still serviceable - I know they are supposed to last a while (40K. ?), but it could be partially blocked. Also Matt, in our so called 'library' or Technical section, we have a comprehensive description and fault finding chart of the CIS system. Perhaps it may also pay to have a compression test - you never know. Regards Michael (Styria)

 

[mathew]

Both pumps are bosch and new and both work mate. When pushing down on the flap you can here the injectors pumping to be sure I removed one from each head pointed in a jar and the spray pattern is beautiful. So I have spark new plugs and fuel hence my growing frustration. There is nothing obvious wrong except I am seeing some fuel in the airflow meter housing which just shouldn't be there. I know these engines won't start with wet plugs so I'm guessing it's flooding at start up but what causes this. I have pulled the cold start injector and it isn't leaking or pouring fuel in as it's not cold enough so what on earth is left? Oh yeah I even purchased a genuine Mercedes Fuel filter.

Cheers Mat

 

[260ebenz]

G'day Mat,

Good to talk to you on the phone today mate thanks for your advice today.

Sorry to hear about The Governor is misbehaving again it's annoying when your car misbehaves!

Like I said Mat contact Perry Penfold MB Mechanic in Newcastle tell him the problem with your 420SEL, Perry will be able to tell you how to fix the car Perry has very knowledge of the W126 series.

Perry's phone number is: 49 684 312 hope this helps Mat?

Let us know when Gov is running again.

Cheers mate,
Tim.

 

[Styria]

Hi Matt, seems as though you have done everything - I have run out of ideas. What about Joe on 9833-2646 and discuss it with him It's worth a try. Regards Styria

 

[Tony66_au]

Id be checking the air flow metering and throttle body mechanics, a mates 300E did that exact thing and it was a mechanical issue in metering.

 

[mathew]

I suspect the metering in the distributor has gone to the Gods grrrrr. My mechanic was amazed at what I had done and even the boys at the local dealer are scratching their heads. I guess it's time to try a second hand fuel distributor if that fixes it anyone know where you can purchase a decent reco one from. Get this a new one out of the Classic Center is a staggering wait for it..................................................................................................................................................................................................................................................$6800

 

[Oversize]

Could it be as simple as a substantial vacuum leak?? A split hose or similar?? Even so I still would've thought you'd get a splutter....

 

[260ebenz]

I suspect the metering in the distributor has gone to the Gods grrrrr. My mechanic was amazed at what I had done and even the boys at the local dealer are scratching their heads. I guess it's time to try a second hand fuel distributor if that fixes it anyone know where you can purchase a decent reco one from. Get this a new one out of the Classic Center is a staggering wait for it..................................................................................................................................................................................................................................................$6800

$6800 spare change for a 'Battleship' owner surely Mat? LOL.


That is unbelievable that quote from the Classic Center!!

Surely you can get a recond distributor in AUS?

Ring MB Classic Star- John Tsolakis 9790 1126, John is excellent for MB parts.

Silver Star Spares in Sydney.

MBV Parts at Kemps Creek speak to Graham dealt with him before he was very good.

Either Perry Penfold or Barry Roberts in Newcastle told you before both blokes are good for MB parts.

Sorry to hear about this problem with the Governor very annoying mate wish you all the best with it mate.

Cheers Tim.

 

[mathew]

Ok guys it is the fuel metering/distributor unit, how do I know you ask? Well fitted new plugs totally dried out the cylinder bores and the entire intake system took ages!!!!!!!!!!!!!!

So then I pulled the fuel pump relay and whilst young Harry took great joy in turning the engine over to start, I opened the throttle wide up and poured 40mls of fuel down the opening. Presto engine spluttered straight away I repeated three times and he is burning the fuel straight away.

So despite having excellent fuel pressure and flow at the injectors it would appear something in the meter or distributor has called it quits leading to substantial flooding. Hence the no starting issue and it would explain the excessive black smoke at start up I was getting before the whole thing died. So the search is on, for an entire fuel assembly not cheap!!!!

Lesson learned people, despite what some think a W126 is now old and buying parts for it new whilst easily available, is hellishly expensive. So I have made a stupid offer on a running donor car and if I get it I'll be stripping everything out of it. Driving a 30 year old model is great, but you had better have a spare car for parts I pity the W116 owners trying to source obscure parts today. I love the car so I'm happy to spend on it, but one needs to be careful about owning a classic no matter how nice it is.

Thanks for your help guys.

Cheers Mat

 

[abl567]

Mat,
Was the Classic Centre price for the fuel distributer from Felbach or Irvine?
Ant