08 MC engine missing any suggestions?

[gregy]

@Jody Seal or anyone else. My ski partners 08 Mastercraft, Prostar 197 with Indmar engine is missing, it has just under 400hrs. Misses randomly but seems worst when turning around the islands. He replaced cap and rotor, spark plugs and didn't help. Local dealer said maybe water in the gas so he pumped it all out, no change. We put a fuel gage on fuel rail and fuel pressure was very steady.

 

The check engine has not come on at all during this. Problem started happening sudden. Ran fine on day and then the next it started acting up.

[skihart]

What motor?

[boarditup]

Two additional possibilities - the fuel pump can act like this. Some of the plastic pieces can break and float around at the wrong time. Finally, the air intake system can be dirty. Clean out the BFFA and the throttle plate. I'd start with the cleaning with a couple of cans of MAF cleaner.

[Mateo_Vargas]

Maybe a problem with the Drive by Wire throttle. Seen this happen on a lake boat and would miss at the speed that you would go around a turn island.

[eleeski]

The engine is missing? How did they hoist it out of the boat? I'd check the older boats to see who suddenly ended up with a new ZO engine.

 

Missing meaning running rough? As Rosannadanna says, "Nevermind".

 

Eric

[gregy]

It's an MCX. It is dbw, I was thinking there might be a problem there. Eric, yes its still there, I was laughing when I wrote the title too.

 

I was thinking fuel pump, but think we eliminated that by check pressure. I forgot he put new fuel filters also.

[boarditup]

DBW connections can get some corrosion - PB Blaster and dielectric grease may take care of the issue. The fuel pump can be intermittent - testing fine at rest and causing problems underway.

[lb]

check and clean all your grounds. mine was doing the same thing and continued after changing the cap, rotor plugs and wires, and flushing cats. I took it to the dealer to be plugged in and he told me there was a bad batch of caps made and he had replaced 26 bad one;s just a day or 2 after replacing the old ones. but if it was not that check all the grounds.

I didn't see plug wires on your list, that is good maintenance with the moisture heat they operate in.

 

converters- my boat has well over 1000hrs and was very quiet as well when i first got it. there is a school of thought that says you need to run a boat with converters at over 4000 rpm's for more than 10 min every 50 hrs or so. I bought mine from a ski school and after the items above and 5 or 6, 10 to 15 minute trips at full throttle it is now obnoxiously loud and performs quite well.

[RichardDoane]

@gregy - new ignition wires, with a dab of dielectric grease on each end, then retest, all it takes is one poor connection to get a misfire under load

[gregy]

Finally figured out the problem with the 197. It had approximately 400 hrs. The distributor had a worn drive gear. The distributor housing was plastic, think that had something to with it (housing flexing). It now has an aluminum housing distributor.

[jdarwin]

I was going to say "cam retard setting may be off" which the worn gear would cause. The CRS in my 2007 SN was off 2 deg and it made it miss when cold. Hooking up to the engine's computer w/ diagnostic program may have caught that.

[gregy]

@jdarwin we had a computer with diagnostics, we weren't experts at using it though. The boat ran perfect today. I just can't believe that that distributor gear wore out that soon with less than 400 hrs. The teeth were worn to about half the thickness of the ones on the replacement distributor.