I was brought a 1988 190e to get running correctly. It initially would stall out just about the time it reached operating temperature and not restart until it cooled down. I looked the vehicle over to find a loose #4 plug wire. a #3 plug crossthreaded 1/2 the way out of the hole. what appeared to be the overload protection relay unplugged, the throttle cable pulled tight, so it would never hit the decel switch, onboard diagnostics not working and a few other minor things. I now have the diagnostic monitor working, the plugs and wires installed correctly. I have found that the fuel pump and distributor have volume and pressure. the vehicle has spark and good sensor readings except for the throttle switch's idle position is not functioning( i jumpered a wire to simulate the vehicle is at idle. someone had accessed and turned the allen head screw going down the airhorn area. When cranking there is spark , good compression, but no fuel in the injector tubes. and the cold start injector is not being activated. if I supply fuel or pulse the injector I can get the vehicle to run(briefly). What type of setting is needed for that allen head screw down the airhorn and can it cause a no-fuel starting issue?

The allen-head adjustment is mechanical mixture control at the fuel distributor. If the car runs as you say, it can't be too far off, and would not shut off fuel delivery. That would be the job of the EHA on the side of the unit in normal operation. More likely, if the OVP is out and loop control thus disabled, would be a sudden loss of fuel pressure, e.g. bad fuel pump or fuel pump relay. Enrichment at starting via the cold-start valve should only last a few seconds in mild weather.

Steve

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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7