280SE 4.5 Hot Start Problem

[MikeM]

A friend of mine is having a problem with his big body. Listed as MY 1973.

After running and getting warm, Leave the car from 10-30 minutes and come back to restart, the car acts like it's starving for fuel. the car tries to start, sputters for a few seconds then finally catches if it starts at all.

Cold Starts are as expected, Car has had all hoses and vacumm lines replaced, filters replaced. Injectors checked for flow, fuel pressure checked, major tune up, Runs great when running, etc.

Any thoughts?

Seems like an issue with no residual pressure in the fuel circuit after getting a hot soak.

Couple of people mentioned a fuel accummulator, and/or check valve, but he can't locate it either on the car or in the manual.

Any insight appreciated.

Thanks,



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Mike Mullins
71 250 Coupe
92 400E Sedan
90 944/S2 Cabriolet

[Aaron]

Those early 4.5s with the old fuel injection suffered from hot start problems. The fuel vaporizes in the lines (hence the term "vapor lock"). One quick fix is to spray the injection pipework with cool water if you're in a hurry. Additionally, cycling the key on and off a few times will move cooler fuel to the engine, and should assist in starting it. I am fairly certain that you can retrofit a setup from MB which can be mounted on the electrical rack in the engine bay which will automatically run the system in cold start mode at all temps to accomplish the same thing as manually cycling the key on and off. Hope this helps!


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Rgds,
Aaron Greenberg
MB technician
Precision Motorcars, Cincinnati, Ohio
'67 250SE Cabriolet
'77 450SL
'79 6.9
'80 300SD
'85 380SE
'89 420SEL
'93 300E 2.8

[MikeM]

Aaron, I'm in Cincinnati myself. I'm going to have my friend give you a call and let him work it out if it's OK.
Thanks,
Mike Mullins

744-6781 W
779-6271 H

[Aaron]

Mike,

I won't be back at Precision until the 11th, but he can call me on my cellular phone at (330) 802-7921.

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Rgds,
Aaron Greenberg
MB technician
Precision Motorcars, Cincinnati, Ohio
'67 250SE Cabriolet
'77 450SL
'79 6.9
'80 300SD
'85 380SE
'89 420SEL
'93 300E 2.8