350 MAG MPI died underway, won't start back up. No Alarm/Code?

[RTonelli]

Unloaded my Rinker 232 from the trailer, idled a bit with no issues (10 min MAX.) while I waited for my buddies to arrive, and headed out and within 1 minute of cruising at 3200 RPM, the boat slowed down quick and bogged out, as if I throttled down back to neutral. Tried to restart it and got nothing. Got towed in and brought the boat back home. Trying to start on the trailer, I can see puffs of black smoke coming out of the exhaust as if to say its flooding and no spark to fire the motor. I have VesselView on the boat and it is not throwing any codes or no alarms, all temps and PSI were normal. I haven't been able to check for spark yet, but what should I be looking at? VesselView reads RPMs while cranking, so I'm assuming the crank sensor is good. Does the 350 Mag have a CAM sensor? I will be checking for spark in the morning, but what is the best way to go about doing that? I'm used to smaller motors and usually ground the plug on the head and attempt to start it. Lastly, the fuel pump does kick on, and I changed the fuel/water separator because i had a spare and it checked out good. Because the pump is kicking on I think it is safe to eliminate Neutral Safety and Lanyard Kill Switch, but please correct me if I am wrong.

 

[tpenfield]

Aren't MPI engines fun

They work great until they don't . . .

Your Vesselview may not give you much info. I would check all of the connections to the ECM and the various sensors. since you are getting reading from the Vesselview, hopefully that means that the ECM is OK.

Checking for spark would be a good next step, but beyond that, you might need the computer diagnostics to see more of what is going on . . . or not going on.

 

[alldodge]

What is the engine serial number?
Does rpm is showing on VV when cranking?

You should have the flat style distributor cap and they are notorious at going bad without warning but still look good. most keep a spare onboard for when they act up

Your CPS is on the timing chain cover. If fuel pressure is good, rpms are at least 300 while cranking, and there is no spark, and distributor cap has been replaced, then best guess is the CPS

And do verify you have 12V at the coil

 

[Scott Danforth]

start with the basics.

what is in the fuel lines (empty the contents of the fuel filter into a clear container and look)

what is the fuel pressure

 

[RTonelli]

Good news is it runs. New cap and rotor and she fired right up, but with a weird suction noise. It’s coming from where the IAC muffler should be. It’s not there. I’m not sure if it was there previously or not, but I did take the spark arrestor off while investigation the no start issue and it backfired once through the intake. I’m very concerned that it got sent into the intake manifold and is somewhere in there, or in the motor. I’m very nervous over this. What should I do! I can’t seem to find it anywhere in the bilge or engine bay. I ordered a new muffler but freaking out over where the old one went

 

[alldodge]

If the muffler went into the intake it will do no harm, its a piece of foam and will just burn up and go out the exhaust.

With a backfire, need to check timing

 

[QBhoy]

We need to get a sticky at the top of the page for mpi diz cap issues. Without doubt 9/10 times this is the answer to running problems with the mpi

 

[alldodge]

We need to get a sticky at the top of the page for mpi diz cap issues. Without doubt 9/10 times this is the answer to running problems with the mpi

Sticky's are great but very few ever read them before they post :facepalm: but this is also good If folks read all the stickies before posting, we would have way less questions, and then how we going to get our post counts up

 

[QBhoy]

Fair play. Good enough reason for me, haha.