Since I already bought the oxygen sensor, accumulator, might as well get the injector and seals and see where it lands up!!
thanks for the helps so far guys will keep u posted.

Cold start -> OK
Hot Start -> OK

Warm start -> problematic.

I agree with one previous post. This is a typical symptom of slightly leaky fuel injectors.

When they leak a little, hot start is not affected because there is not enough fuel to leak out. Cold start is also not affected because there is enough time for the leaked fuel to evaporate.

Warm start is affected because there is leaked fuel (flood). Enough fuel has leaked and not enough time for it to evaporate. You can further confirm by doing a double start. Start it (it may not start). Stop and wait for a few seconds. Start it again (it should start now). The first (failed) start will burn off the leaked fuel and the second start will be successful.

Before you try to replace the injectors, try to clean using an approved fuel injector cleaner. Contrary to what have said by many, MB does approve two injector cleaners in their 2006 approved service products for all engines. On page 15, one is an MB product that you can buy from the dealer. Another is Chevron Techron.

You can get a 20 oz bottle and put in the tank and filled it up. Do a mixed driving and preferably over a few days. Let the car sit after driving (Let it leak so the cleaner can clean the injectors to simulate the leaky situation). Or you can go to Advance Auto Parts and get two 12 oz bottle (buy one get one free before the end of this month).

You should notice some improvement after one application (a few successful warm starts). You may need a second application. Change the oil after the applications.

This should cure deposit related leaks. If it is an internal (parts related), then this cleaning will not fix.

i am having the same type problem with my 1985 500 SEC USA version. I can be driving with my foot on the gas and the car will lose power and go dead. then it is hard to start but if i let it sit for about a minute it will re-start with ease what do i need to do to fix it

i am having the same type problem with my 1985 500 SEC USA version. I can be driving with my foot on the gas and the car will lose power and go dead. then it is hard to start but if i let it sit for about a minute it will re-start with ease what do i need to do to fix it

This is helping me zero in on my situation, although I am guilty of what stevebl scolds us not to do, namely throwing parts at a problem.

My car, 1991 300CE at 143m, bought it at 111m. It has always had a slightly sluggish start. I occasionally get a quick cold start so that must be the cold start valve working? But for most cold starts, it doesn't catch for a couple of seconds, but it will catch. If I let go too soon and it does not start, and then I restart, it catches immediately. A hot start is fine also. But anything less than a hot start, it stumbles. The car otherwise drives and idles perfectly. I decided to change the fuel filter and since I was going to be rooting around there, I decided to change the accumulator. I only have history back to about 87m and no record of these changes. It's been a few days, and absolutely nothing has changed.

I have used Techron every so often since I bought the car. Some new injectors are on the way, so I'll give them a shot.

Thoughts?

Thanks,

glenmore
1991 300CE
2000 C280
1990 LS400

give a try replacing the injectors and see what happens

Thanks loubapache -- will do as suggested and keep you posted!!

I am having similiar issues with my 1991 300 sl . Morning starts are normal, after sitting for ten minutes to 1 hour the engine stumbles to life, after sitting outside in the hot sun ( 75-80 degrees ) this is my worst condition , it will sometimes require several attempts to get started,starts after short shut downs such as refueling are normal. Can flooding from leaking injectors be a problem after 8 or 9 hours if the vehicle is sitting in the hot sun??I was thinking about pulling spark plugs to see if they are fuel soaked to verify flooding ... any thoughts? Thanks dan

Also was thinking about coolant temp sensor being faulty...normal start after sitting over night (cool temps) difficult starts after warmed to normal operating temps and allowed to sit but not cool to stone cold . Any ideas? Thanks, Dan

Did you ever consider the OVP relay?????

NOTORIOUS for crap like that-

Overage Voltage Protection relay

Is there a reliable way to test the OVP relay???

Does a 1991 300sl have an OVP if so where is it located? Dan

Stargazer, well how did you do?what where the results of your changes and did you do one at a time so we would gain the info needed for others?JNT

I was under the impression that the cold start injector,only operates when it is very cold out,That it dose not work just any time you start the car! Temp must be low enough for it to get the signal to inject!JNT

On to the injectors! On removing the air filter, I had a eureka moment, when I saw that one of the injectors had an obvious leak. Luckily it was one of the easy ones to get to. The pairs of injectors on either end have great access but the two in the middle look difficult. I changed the leaky one and one other and am waiting some more in the mail. The injectors themselves look fine, the delicate tips look just like the new ones. The fit of the new Oring and new insulator in the head is tight. I had to tap them in with a 15mm socket. The old ones came right out. The old seals were very brittle and mashed. It was nice to freshen up the seals but after a couple of starts, I don't think this is the cause of my stumbling start.

glenmore
1991 300CE
2000 C280
1990 LS400