mercruiser 5.0 mpi cross fire problem

[aarrigo]

I have a 2002 merc 5.0 MPI 260hp that gave me a strange problem that I was hoping some one can shed some light on.
When going to start the engine it was extremely difficult starting and after letting go of the start key the engine coughed backwards. This was definitely note something you would see very easily. In doing so the engine ingested water and filled 7 out of 8 cylinders causing the engine to lock up. The engine would no longer crank. After replacing a strater, bringing it to a mechanic who miss diagnosed it and replaced the exhaust flappers, removing the risers and manifolds. It did the same thing. In the end it was a bad set of wires that apparently were cross firing causing the engine to go in reverse.
Is this a common problem and can some one offer some insight?
Thanks
Augie

 

[Reel Poor]

Re: mercruiser 5.0 mpi cross fire problem

The most common cause of crossfire would be distributer cap and rotor wet or cracked. While it is possible that the wires were causing your problem, I hope you changed the cap and rotor also.

 

[calwldlif]

Re: mercruiser 5.0 mpi cross fire problem

Yes wires will crossfire.
My best guess is if they cross over more then 1 time(twist) and run close to a conductive piece
of metal they easily jump spark.
I had a hard practical example during
a complete tune up.
New everything and the first start was anything
but smoooth...........
if you did a wire change and this happened,
I understand.
If it happened later then I suspect bouncing around
put the wires in a position to crossfire.
Sorry, you got "crossed up"