S124 300-24v non start

[tintinmt]

Hi, Your thoughts on an explanation for this:-

Stopped off a Wickes but when I returned to the car it started and ran but then cut out almost immediately. RAC diagnosed as 'no spark' probably due to failed coil. Car recovered to my usual Merc specialist.
They have replaced the coil, distributor cap and rotor arm but the car still refuses to start. They think there is no fuel and are continuing to investigate.
Any thoughts on what could cause both spark and fuel to fail at the same time?

 

[Ian B Walker]

Engine management module on the inside of the passengers wing. Had it on mine some time ago.

 

[tintinmt]

Thanks. Strange thing is that apparently they now have spark and fuel pressure but no fuel to the injectors.

 

[grober]

As Ian says it could be the EZL ignition unit on the inner wing [ rare as hen's teeth now and quite expensive as a spare part from Merc ] or it might be the rather elaborate fuel pump relay beside the battery Its a rather large unit on the 300-24v CARS unlike the standard fitment [ again not cheap to replace!]

FPR problems can difficult since they are 2 stage- in the first they pressurise the system on a signal from the ignition switch but then need an "engine running" signal from a different source to keep the second stage activated and the pump going. There may be fuel pressure because the KE fuel system has an "accumulator" [spring loaded diaphragm] device beside the fuel pump which mains fuel line pressure to aid restart but not FLOW Symptoms sound a bit like that?

 

[mazza]

Thanks. Strange thing is that apparently they now have spark and fuel pressure but no fuel to the injectors.

Hi

When your engine decided to shut down, was the engine under load or just idling?

Lack of fuel pressure would stop the fuel injectors from opening

The mechanics are now trying to start the car from cold so this means the ECU has to start the engine under cold start conditions so it will need more fuel which is supplied from the cold start injector and the ICV idle control valve must also be working ok, no valve...no start.

Have they checked the idle control valve??? do ask them to check this..specially if car died while idling.

as pointed out, the FPR controls a lot of stuff even more if its a cold start

mazza