Hard start when hot on 190E 2.6
 

I'm having difficulty starting intermittingly when hot on my 1992 190E 2.6. It has new plugs, wires, dist cap, and rotor. It starts fine when cold. I can't find specific help for these symptoms. Can anyone help.

You have leaking fuel injectors which are flooding your engine.

Drains off by time engine is cold, and besides cold starting requires rich mixture in any event.

Verify by holding down accel pedal when cranking.

Is the idle rock solid when warm and in Neutral or does it wander up and down?

Every MBZ I have owned up to the mid 90s has stated in the manual that in some cases you must slightly depress the gas pedal when starting warm. Does that help, or does it still hesitate to start hot even when doing this?

that's probably your fuel accumulator down near the fuel pump. it's there to maintain pressure in the fuel system, cold starts are fine because the cold start valve squirts fuel in to get the engine started.

There are several causes of hard starts hot.

The above can all cause the problem, but you should also take a look at the condition of injector seals, idle control valve hoses, and the boot between the fuel distributor air horn and the throttle body.

Air leaking in that does not go through the air meter venturi will cause hot start problems, typically a start and immediate stall (extra fuel when cranking). If you also have rough idle or variable idle speed, check for vac leaks (including all the vac operated things like climate control and tranny shift modulator. Occasional stalls while decelerating, especially abrubtly, are indicative of a leak.

If it is otherwise running well, suspect a bad accumulator -- this will permit vapor lock.

A bad fuel pump relay and/or bad over-voltage protection relay can also cause hot start problems -- the hot relay is intermittant, and you have either no fuel or no ignition momentarily. If you have occasional stalls while driving, it's the fuel pump relay or pump