We have always had a warm start problem in our 1991 300TE. Never really bad, but just irritating. It always seemed like a loss of fuel pressure or something, you had to rev it pretty high to get it hold then it was fine, not even rough at idle. We have chased down all kinds of leads over the years replacing cap/rotor/wires/plugs, Temp sending unit, OVP, Valve guide seals, head job, hydro-electric actuator valve. Now the odd thing is that the only thing that solved the problem was changing the injectors. But this only worked for about two months, then the warm start issue returned, but we lived w/ it for almost a year. Now things have declined to the point that it is really hard to start and is real *****y (burbling and missing even backfiring once or twice) up to 15-20mph, then ok, but a little sluggish after that.
My question is what is going on with the injectors? Why did replacing them fix the problem only to have it return after a few months? (And not very many miles in that time...only 101k mi total, so she hasn't been driven to death, but still gets her share of highway time)
I have her torn apart right now. She will get a new fuel filter and I will intensly inspect the injectors, but I don't know what I hope to find. Ilove the car but I can certainly not afford to put in injectors every two months!
Thanks in advance all!
-Matt-

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Currently:
1972 350SL Euro 4spd
1973 BMW R75/5
1981 BMW R80GS
1995 FZJ80 with OM606 Conversion In Progress

Ok...I've gone through my records and I see that we replaced the injectors when we did the head/valve job, so that may not be the best thing to go on. I am not the primary driver of the car, but apparently that was when it ran best; afer the head/valve job with the new injectors. Someone apparently thought it was the injectors that fixed it (notes in the maintainance log elude to that).
The major issue is that it runs great cold. And then it runs like sh** when it gets warmed up to operating temp. If anyone has any idea what would be causing a warm only runability issue I would love to hear it!
Thanks again.
-M-

__________________
Currently:
1972 350SL Euro 4spd
1973 BMW R75/5
1981 BMW R80GS
1995 FZJ80 with OM606 Conversion In Progress

The valves have a base setting that uses shims behind the lifter and between the lifter and valve. Since you had a valve job performed it would be safe to assume that the valve faces were machined as well as the valve seats. Removing material from both surfaces will cause the valves to sit higher at the top, possibly impacting this base adjustment. You may want to start by having this checked then adjusted if required. I’m not suggesting this is the actual cause but given the history it may be worth investigating before devoting anymore time to rooting around.

In true MB form it will require the use of Special Tools.