1990 300CE fuel draining into intake, what would cause this? - PeachParts Mercedes-Benz Forum

ROLLGUY · #1 04-19-2016, 08:32 PM

I took my car (1990 300CE) to get smog tested, and it failed. They said it was running rich, and gave me a list of parts to replace (all rubber hoses on the engine, injector seals, breather hoses etc). I did all that including an oil change, and when I started draining the oil, I had to quickly put another pan in place before the first one filled up. I got about three gallons of oil (and I assume gasoline) out of the sump. When pulling the throttle body to replace the gasket, I noticed a puddle of gas in the intake manifold below the throttle body. I can only assume gas is leaking into the intake system somehow when it is running, and after the engine is turned off. What would cause this to happen? I am not as familiar with gassers as much as I am with Diesels, so please take it easy on me LOL! Thanks in advance, Rich

duxthe1 · #2 04-19-2016, 11:13 PM

Sounds like a plunger seal on the fuel distributor.

ROLLGUY · #3 04-20-2016, 10:08 AM

How easy is that to replace? Is that part available, or should I just get a used one at a wrecking yard?

duxthe1 · #4 04-20-2016, 02:31 PM

The part is available but I don't know the # Its kinda a pita but diy if you are methodical.

ROLLGUY · #5 04-20-2016, 09:59 PM

Quote:

Originally Posted by duxthe1

The part is available but I don't know the # Its kinda a pita but diy if you are methodical.

Do you know that f there is a DIY somewhere? Youtube?

slk230red · #6 04-21-2016, 10:22 AM

Quote:

Originally Posted by ROLLGUY

Do you know that if there is a DIY somewhere? Youtube?

Check these out.

Rebuilding CIS-E Distributor....

CIS fuel distributer cleanout w/pics - Pelican Parts Technical BBS

http://www.cis-jetronic.com/public_doc/07.3-0997-06.pdf

ROLLGUY · #7 04-21-2016, 10:38 AM

Quote:

Originally Posted by slk230red

Check these out.

Rebuilding CIS-E Distributor....

CIS fuel distributer cleanout w/pics - Pelican Parts Technical BBS

http://www.cis-jetronic.com/public_doc/07.3-0997-06.pdf

Thank you so much for the useful information!

optimusprime · #8 04-21-2016, 02:49 PM

Rollguy this is the fuel regulator on your car .Remove the plastic tube and start the car .See if fuel comes out of the regulator.

optimusprime · #9 04-21-2016, 05:51 AM

Rollguy what engine do you have in the car ?. Is it an M103 ? If 103 it can get in from fuel pressure regulator .But again it can do the same if fuel distributor seals have rotted out . How is it running ?

ROLLGUY · #10 04-21-2016, 10:12 AM

Quote:

Originally Posted by optimusprime

Rollguy what engine do you have in the car ?. Is it an M103 ? If 103 it can get in from fuel pressure regulator .But again it can do the same if fuel distributor seals have rotted out . How is it running ?

I think it is an m104. It is a 3.0 six cyl. It seems to run okay, other than a slight flat spot in the acceleration.

optimusprime · #11 04-22-2016, 04:30 AM

Rollguy i am shooting blanks here, i need to know what engine you have ie m103 m104 or i can not help you .I research one engine to find you have another. Nothing in your profile to go by.

ROLLGUY · #12 04-22-2016, 10:43 AM

Quote:

Originally Posted by optimusprime

Rollguy i am shooting blanks here, i need to know what engine you have ie m103 m104 or i can not help you .I research one engine to find you have another. Nothing in your profile to go by.

All the part #s that I have been getting (Pelican Parts) have been 104 #s, so I assume it is a 104.

Rick76 · #13 04-22-2016, 09:07 AM

You can probably check to see if the control piston is leaking with a dental mirror just after shutting the engine off.
If leaking, the part number of the control piston seal ring is A 011 997 71 48. You will also need a A 004 997 06 48 seal between the fuel distributor and housing.
The procedure is covered in the FSM under 7.3-1660.
It is critical to get the screw plug set to the same depth as before.

Rick76 · #14 04-22-2016, 12:00 PM

You have a M104.980.
It's an early 104 with KE-Jetronic fuel injection.

ROLLGUY · #15 05-06-2016, 07:57 PM

I finally got some time to work on this project. After replacing all the rubber hoses, injector seals, and all gaskets and seals in the intake system, it still drains fuel into the intake. I took the advice of duxthe1 and decided to look for a complete fuel distributor in a wrecking yard, and replace it (rather than just replace the plunger seal). I found one today, and did just that. It does not leak into the manifold anymore, but it would not idle either. I adjusted the flapper (not sure exactly what it is called) a little by leaving the center bolt a little loose, and moving the flapper until the idle smoothed out. It idles great now, but it is really boggy, and does not rev up well. It also is very hard to start (cranks for a long time before eventually starting). It was slightly boggy before, but much worse now. Did I get a bad fuel distributor? Should I go back and get a different one and try it? The distributor was from a single cam engine, and mine is dual cam (not sure if that makes a difference). I am not sure where to look for cause of the bogging problem. Anyone have any ideas?