2011 4.3 MPI MerCrusier Will not start

[randysmith]

2011 4.3 MPI Mercrusier started up with no problems just spinning over 2-3 seconds until 2 weeks ago when I put it in the water. Now it doesn't even try to start. Just spins. It will spin 3-4 times and then drag for 3 seconds and then start spinning 3 - 4 times and then drag. It is not the battery. It never did this before.

Also, it is getting fuel. If you spray a little starter fluid, it back fires slightly when you let off the key. I attached a mercury spark tester to the plugs. Some fired white and a couple fired orangeish white. Whatever it is, it was sudden.

 

[alldodge]

it is getting fuel. If you spray a little starter fluid, it back fires slightly when you let off the key.

This doesn't mean its getting fuel, this means its not getting spark. The spark you are getting may not be at the correct time

Motor is probably going to need to be scanned for codes, thinking its either cam/crank sensor or the distributor cap and rotor. To try something, I would replace the cap and rotor first because they are known to go bad.

How about a motor serial number?

 

[QBhoy]

Hi
its the battery. 100% on this. Happened to me. The obvious thinking is that it won’t be the battery because it’s turning over but these mpi have such dependency on a strong electrical supply to fire. What happening is when you are turning it over, it’s drawing lots of current and voltage. So much that the engine is starved of enough juice to fire the high demand system. When you let go of the key it momentarily has enough power back to the engine (because the starter isn’t stealing the load anymore) but only for a split second. Not enough.
Trust me on this. Puzzled the crap out of me for a full day of fault finding. Get a new battery and she’ll go.

 

[QBhoy]

How did you get on with this ?