Another Mercruiser EFI question!

[Quigs]

Just thought I would post this up to see if anyone could give me guidance in the right direction. My engine, since a rebuild, has never had a problem starting, just a flick of the switch and its fired up. However recently, after running it for half hour or longer, when I go to restart, it immediatley starts and then immediatley stops without hesistation. Does this for few times and then eventually starts.

However last week, on the pontoon luckily, I tried it again after a trip out to the Eddystone and back, and it kept failing to a point where it wouldn't start at all, not even a hint of a detonation.

Went back in the morning, tried again and started first time. I really need to sort this as my confidence in restarting has somewhat been minimised. So anyone with any ideas? /forums/images/graemlins/confused.gif

 

[spannerman]

The fact it starts from cold eliminates most of the possible faults, so its more than likely heat related.
The fact it eventually starts rules out ignition as this usually works or it doesn't.
So I think its fuel related and wonder if you get a vapour lock from heatsoak after running a while and turning off, my old V8 carb did this till I changed the cooling system to freshwater cooled.
It would be worth getting a fuel pressure gauge and connecting it to the schraeder valve on the fuel system and seeing what the pressure is when running and after its been turned off for a while to see if it leaks down.
It could be that one or both of the injectors are leaking at rest and dumping fuel into the manifold which will make for hard hot starting. The way round this is to open the throttle wide 'in free' while cranking and as soon as it catches pull it back to idle, this will get the much needed air in to correct the over rich condition.
The other thing is to try to prime the system by switching on the ignition and wait for the buzz of the pump to stop then cycle the ignition off and on again several times, if this helps then its definitely lack of fuel when starting from hot.

 

[Quigs]

Thanks for the reply. What I can't understand is that when it does start, it starts as normal, no lumpiness, struggling etc, it just runs and then dies instantly a few moments later. I did the full throttle thing when it packed up for good and nothing. The fuel is priming ok, and Ive also let the pump build up pressure before starting.

 

[zt260]

Is there any body near you that has got the diagnostics kit that could plug it in for you to see if any error codes are showing,if your in west yorks i may be able to visit and plug mine in,
regds ash

 

[Quigs]

Thanks for the offer Ash, but Im in Plymouth. The thing is I need to get the engine to fail again before I get the diagnostic kit onto it and at the moment its not doing it. Took it out for a spin yesterday, came back and it started every time!

 

[zt260]

The diagnostics store codes for faults that have occured so if its not happening at the moment there is still a chance the error code will be logged
regds ash