1990 Mercedes 300E will not start

[Ninasteel]

Hi all,

I need some help. I have a 1990 Mercedes 300E with a 3.0 gas engine. three days ago the car suddenly lost power, as in foot flat to the floor and my best speed was 30mph. The engine sounded like it had turned in a four banger with a tinny whining sound. As I was only four blocks from home I kept going. By time I git to the drive way I was going about 3mph.
Today it won't start, meaning it will turn over but no vroooom. So here is what I did so far.

1.Took the number one spake plug wire off, connected it to a spare spark plug and turned it over. I saw a good bright spark.

2. Next I poured two tablespoons of gas down it's throat and turned it over. It did not even try to start. I tried this with no throttle and wide open throttle. (this was done to rule out gas delivery issues. Of course I didn't expect it to start, but I did expect it to hit on two or three cylinders)

3. Next I tried holding up the "goldish colored" valve to let more air in (to counter a flooded condition) and I repeated step 2. Nothing.


If my 1973 Mustang responded this way I'd say the timing was waaay off.


Help!!

Nina

[jha2297255]

when you turn the key to position 2 is the fuel pump making the 'noise' that it makes to supply fuel pressure?

hard to describe the noise but its a brief 2-3 sec pressure build up thats def audible if you hava 300e.

[Ninasteel]

Yes I did hear the noise of the pumps. I also took the hose off and turn the key. Gas shot out. I also took one of the lines off to an injector and watched for fuel during cracking. There was just a few drops.

Thanks


Nina

[jha2297255]

i dont know that you can pour gas down the intake (like on a V-8 carb) bc the manifolds so curvy id think it would just puddle and not get sucked in effectively.

theres some sort of $200 black 2 inch 'brain' that controls/regulates fuel pressure by the air cleaner,( mine needed rpelaced but didnt cause no start)

sounds like you have no fuel delivery? clogged fuel distributor? fuel pump not developing enough pressure? (also had to have fuel pump rebuilt)

[mpolli]

Originally Posted by Ninasteel

Yes I did hear the noise of the pumps. I also took the hose off and turn the key. Gas shot out. I also took one of the lines off to an injector and watched for fuel during cracking. There was just a few drops.

So you had fuel pressure at some point but not at the injector? Where did the gas shoot out? Could you have a clogged fuel filter?

[mbdoc]

Just for INFO.

That CIS injection system need to have 82-88psi of fuel pressure to start.
IF there isn't a large vacuum leak at the intake area, you need to have the fuel pressure checked

[Ninasteel]

Checked the fuel pressure. Used a gauge that went from 0-100 psi. Turned on the pump and the gauge pined itself passed 100psi. I'm guessing this is not a good thing. The fuel pump and filter were replaced on 12/16/07. So why the high pressure?

Thanks,

Nina

[mbdoc]

Pressure is measured at the port to the cold start injector.
Not at the incoming line.

If you measured the fuel pressure at that correct port & got that much pressure???
Then either the fuel pressure regulator is BAD or the return line is plugged.

[Ninasteel]

Okay, where is the cold start injector?

Thanks,

Nina

[mpolli]

The cold start injector is another fuel injector that supplies extra fuel for all the cylinders. So that means it is usually located in the intake manifold "upstream" of the other injectors. So if you see an injector looking thing on the intake manifold with a fuel line and electrical connector going to it, that should be it. Sorry I can't tell you exactly where it is on that car.

[richard28]

The cold start injector is virtually above the hose that goes from the idle control valve to the intake manifold, the knobby one that snakes downward. My injector has a blue plastic connector.