i have a '89 300e with 78,000 miles on it, the car runs good but sometimes have to crank it twice to start it. Had fuel pump,fuel filter and battery checked. what gives?

My 87 300E does the same thing, always has since new and now still with 153,000 miles. I have been told that is just what they do and there is no way to fix it and it does not hurt anything. Maybe Benzmac can enlighten us more about the topic....

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Chris
'87 300E

I think this is a relatively common thing with 300E's. Our '87 always requires two or three short cranks when cold; our '91 usually starts after one long (3-4 second) crank. Neither car did this when new, but developed the longer crank times a few years ago. Not entirely sure whether this is normal, but so far we've noticed no other related problems.

-anthony

My '91 300 TE does the same thing as the others listed here. I told the service writer about it and they replaced all of the fuel injectors, and it still has the same problem......


..tracy

Here is the "Top secret repair". All of these have an adjustment for the rest stop on the air flow plate. When the stop is positioned to high, the air that is brought in when first started is not metered to give that amount of fuel. So when the engine finally does start, the mixture is way lean and it dies. Once restarted it continues to run. To fix it a QUALIFIED tech has to adjust the rest position of the air flow plate to have 2mm of deflection when the engine is off. IF HE GOES TOO FAR ON THE ADJUSTMENT THE WHOLE FUEL DISTRIBUTOR WILL HAVE TO COME OFF TO GO THE OTHER WAY ON THE ADJUSTMENT. YOU GET ONE SHOT AT IT!!!!

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Benzmac:
1987 16V
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

We have a '90 300e that will not start on the first try when cold. It usually starts on the second try. We found that if you turn the key to "ON" and let it sit for 5 seconds before engaging the starter, it starts the first try. Maybe the fuel pump need to come up to pressure or something? Maybe someone that knows more about this than I do can elaborate.

I know Benzmac will shoot me for this, but here goes:

The adjustment on the plate he talks about is (on my M103 engine anyway) blanked off with a welded metal plug.... What I did was to remove the bar across the top of the plate (with 2 hex screws). Remove the rubber 'bump stop'... then contruct a new metal bumpstop with a screw thread. Place a bolt in this, so I can adjust the rest position of the plate up and down as I see fit. (change in season).

Works for me anyway... car now starts perfectly (unless its been sitting for days).

Dont try this if your DIY skills are poor... a screw falling down into the air intake will 'screw' your engine.

Bri



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Brian Drought
1991 300CE
http://www.users.globalnet.co.uk/~drought/
ICQ: 2180069

Wait a second...I know there are actually TWO problems here. The cold start problem as Benzmac says is most likely the air plate, however the semi hot rough start problem is probably the fuel check valve. I think both problems can be confused with each other.
yal
88 230e (W124)

bdrought,
i have never seen this plug being blocked off. If yours is, you are looking at the wrong one. I must comment though, it sounds like you did overcome the problem with a little back yard engineering... I love this site. If you find the right plug, you will be able to permenantly adjust it and forget it!! It will then start every time.

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Benzmac:
1981 280GE SWB
1987 16V
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

Benzmac,

I got sent a picture of the plug in question. Took another look, and it seems to be blocked off with a small weld. I dont fancy unwelding it with all that fuel around!

The advantage of doing it my way was that I could get the adjustment perfect by trial and error.... not as nice as the feeling of doing things 'properly' tho.

When theres a will, theres a way!

Brian



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Brian Drought
1991 300CE
http://www.users.globalnet.co.uk/~drought/
ICQ: 2180069

I have a 1991 300E2.6 that had the same problem which I approached differently. I purchased an after-market ignition... Jacobs Omni torquer. It could probably ignite vaseline... I can't get the key off fast enough. Before it took a 2-3 sec crank or even 2 cranks to start. I also got a 2mpg boost in fuel economy.

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I have a 1991 300E2.6 that had the same problem which I approached differently. I purchased an after-market ignition... Jacobs Omni torquer. It could probably ignite vaseline... I can't get the key off fast enough. Before it took a 2-3 sec crank or even 2 cranks to start. I also got a 2mpg boost in fuel economy.
I also had to replace the stock wires with a silicone plug boot. The unit was literally blowing the stock spark plug wires off the spark plug every few hundred miles; the car would start missing and I had to open the hood and reseat the wires.

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