engine not starting

brianflhrci

On our way out last week at a very slow pace since there were boat races and the port engine stalled and wouldn't start.  We limped back in and have been trying to diagnose the issue, so far we've tried swapping IAC's from the other engine with no luck and I've noticed that when I try to start is there is a puff that blows the IAC muffler out if the flame arrester is off.  The engine does turn over and I've tried it with some throttle still no luck.  Any ideas?

skennelly

What engine do you have? Fuel injected or carbed?

brianflhrci

fuel injected mercruiser 5.0's

212rowboat

put your hand on one of the valve covers to feel for valve train activity while trying to start the engine- you'll feel their movement without having to take the covers off, i'm hoping.  also, since you have two- pull the coil wire off the 'good' engine and turn them both over separately, and in attempt to see if the non starting engine seems to be less labored while turning over- it'll also sound different. 

the fact you're getting enough blow back to pop the filter off the IAC means something is amiss... it happening suddenly like that speaks to a broken timing chain.  

aero3113

Is there a chance that you hit the engine cut off switch by accident? I don’t think you would see smoke out of the IAC though if you did but worth a look.

pistole

air , spark and fuel.

brianflhrci

wasn't really smoke, just a puff that blew the IAC muffler out.  Wouldn't I hear rattling if it were the timing chain?