No this isn't a post for adult diapers....

I have a ’87 420SEL with 145K miles, with original fuel injectors, experiencing a warm start problem like so many others who have posted here. If I restart the car within 10 minutes of shutting off, it will start up again fine. Any longer than that and I will have to crank it several times before it turns over. So it appears to be leaking fuel injectors which I’m going to change soon. So if I understand the problem, fuel continues to leak into the combustion chamber after I shut the car off creating a very rich mixture that can not combust. But the next morning when my engine is cold, the car starts fine. How come the extra fuel that leaked into the combustion chamber last night while the car was sitting in the garage doesn’t cause me to have a rough start in the morning? Thanks for your replies.

Well I ain't to sure about that hypothesis. I had/have a similar problem, however I have a slighly rough idle, and 2. sometimes it takes one or two cranks to start , and I have to pump some gas. I knew it was fuel related, and I was leaning towards injectors, and my hypothesis was similar to yours. However I took it to a good Merc shop and it turned out to be my fuel distributor, which is a bit faulty. Who diagnosed your car??

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**A few Hondas etc... etc... Not Worth Mentioning**
83 Euro W126 380 sel Money Pit (Sold)
91 W124 300e 2.6. (Sold) 3.0 Motor is Much better!!
93 BMW E34 Touring Wagon (Sold) Sweet Car!!
91 300e (Just 200k with Ease.)Best car ever ???(Sold)
90 420sel (Black with Tan Interior) Best car ever!!!!!!!

Can also be a bad accumulator letting the pressure drop in the fuel distributor, so that the fuel boils and you have vapor lock after a few minutes.

Get the fuel pressure checked and have the fuel distributor checked for leakage -- nozzles alsol.

You don't have a problem with a fuel leak when the engine is cold because it needs extra rich conditions to fire anyway -- the fuel doesn't burn very well in a cold combustion chamber, so most of it goes out with the exhaust. In a hot chamber, all the fuel burns and you run out of air before the car starts up properly, the plugs get wet with fuel and carbon up and short out.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

I had the same problem with mine. I've read-fuel pump check valve--fuel accumulator--injectors and many other things. I adjusted my fuel mixture clockwise and it cranks perfect now first time everytime and it cost nothing.