Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 09-16-2007, 12:27 AM
Registered User
 
Join Date: Sep 2007
Posts: 3
Start and Stall 88 300 CE 124

Hi Everyone,

I have an 88 MB 300CE 124 M103.

The vehicle has set in my garage for the past year with only 3 or 4 trips in that time consisting of 5-10 miles each. I did add 5 gallons of new fuel this morning as the tank was somewhat low.

The battery would no longer hold a charge. I replaced the battery with new this morning and the car started right away. After idling for 60-90 seconds it stalled. It would restart after waiting a couple of minutes, but would stall after idling for 3-5 seconds max. If I added throttle, it would stall instantly.

The fuel pumps were replaced two years ago with factory new. I replaced the fuel filter this morning, but only after the symptoms were occuring.

I performed several tests and found the following:

The fuel pumps have 12+ volts when cranking and when idling. The voltage to the pumps remains constant for 2 seconds after the engine stalls. When the relay clicks off, then voltage is lost, which is normal. I have jumped the 30/87 or 7/8 on the Fuel Pump Relay to allow the pump to run constant, but the issue still occurs. At no time does it sound like the pumps stop while the pumps are under voltage.

I have also jumped the Overvoltage Relay and the issue still occurs.

I have tested for spark. I have good spark. At times after it stalls, if I try to restart instantly, it may just crank without firing. During this time, I have good spark. I have also pulled a wire and checked for spark during the times that it will run for a few seconds. After it stalls, I can see one or two more sparks after engine has started to stall, but the engine is still turning over due to the momentum of the engine. For this reason I believe that I have elimitated Ignition as a possible cause.

Back to fuel. After it stalls, I can crack the fuel inlet line at the Fuel Distributor and it sprays under high pressure. I know this is not a scientific method of testing, but it is not running out of fuel due to fuel line supply to the fuel distributor.

Twice (over 50 or so starts) the engine did allow me to rev to approx 3000-4000 RPM's running very smooth for several seconds, then the engine abruptly stalled the same what it had been doing at idle.

The symptoms seem like a classic fuel pump relay, but like I said earlier, the pumps have voltage for a couple of seconds even after the engine has stalled and the symptoms never changed even with the relay bypassed.

I did disconnect the power to the EHA Valve and tried again, It stayed running for approx 20-30 seconds before stalling, but was very rough and I had to give it some gas and also seemed like I had to depress the Air Mass Plate down to allow some airflow.

I could use some help and ideas!

Sean

Reply With Quote
  #2  
Old 09-17-2007, 10:19 PM
Registered User
 
Join Date: Aug 2001
Location: Houston, Texas
Posts: 393
Vaccum leak in the boot under the air sensor ? General leaks in rubber hoses parts ? Spray carburettor cleaner to see if there is a change in RPM when sprayed at various intake areas such as injector seals, idle valve hoses, etc.
Check vaccum at idle also, should be between 16-22 inch Hg, if not then the problem is on the exhaust side, open the exhauts manifold and see if the problem goes away, if it goes away, need a new CAT.
__________________
Saumil S. Patel
Reply With Quote
  #3  
Old 09-18-2007, 02:41 AM
Registered User
 
Join Date: Sep 2007
Posts: 3
I appreciate the thoughts. I have had a bad Cat before and this doesn't act anything like that did.

Vacuum leak would really only apply at idle. Once I was able to get engine about Idle RPM, then it should run even with a vacuum leak, all though it might run rough. During the few times I could get the engine to rev to say 3000-4000 RPM, it was smooth and not missing, then just like that, instant shut off, just like I turned the Ignitiion switch off.

The engine shuts as quick as I can snap my fingers. It doesnt struggle or starve. It is like something is limiting the fuel supply, then like some sort of an electrical device is shutting off the fuel supply instantly.

As I mentioned, I could get it to run if I disconnected the EHA Electrical Plug, then it runs very rough, but I am able to rev up the engine and keeping it running for a bit. The only change the EHA would make is fuel and it makes a dramatic difference when unplugged.

I just don't know what the symptoms of a failed EHA are?????

Thanks,

Sean
Reply With Quote
  #4  
Old 09-20-2007, 12:15 AM
Registered User
 
Join Date: Sep 2007
Posts: 3
Bump????????

Any Help out there??
Reply With Quote
  #5  
Old 09-20-2007, 08:11 AM
Registered User
 
Join Date: Mar 2006
Posts: 17
I had the same issue with my 87 300e over the past week. Did the same diagnostics you did..I felt it was fuel pump relay, but it turned out to be a failing coil...swapped out the coil from aW201 and it was immediately "cured".. just a thought and easy to check. Best of luck.
Mike
Reply With Quote
  #6  
Old 09-20-2007, 11:23 AM
Registered User
 
Join Date: Aug 2001
Location: Houston, Texas
Posts: 393
I am not sure a bad EHA would cause an instant shutdown. EHA control is I think the only output from the ECU (fuel injection computer), and the car should run without the ECU control, without such control, the emission outputs cannot be controlled, and proper dynamics cannot be achieved, i.e. acceleration/decceleration control, but the car should run. So in my opinion, EHA failure is less likely to cause your problem.

__________________
Saumil S. Patel
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 01:30 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page