2012 4.3 mpi does not hit wot rpms

[Kglassner]

The engine seemed to stutter at high rpms then it would not reach above 4000 rpms. Clogged fuel filter? Blocked air intake? Bad ignition module? Thanks in advance.

 

[alldodge]

New to you boat, and if not new, when was it last used?
Did it reach rpm level last season?
What has been done to the motor this season?

 

[Kglassner]

It has run fine the last month or so. I've had this boat about a year. I try to take it out at least once or twice a week. Back in December I had some regular maintenance done on it. About 3 months ago I had to change out the ignition module. It has run fine up until last week.

 

[alldodge]

With MPI motors and more so with your year and higher, they need to be scanned for codes if you don't have smartcraft.

Have a engine serial number?

If you have not change the fuel filter, then remove and dump the contents into a clear container. See if there is anything other then clean gas.

Replace with a new filter

If it idles and starts fine, then check fuel pressure at the rail (item 13)
https://www.mercruiserparts.com/bam/...31505/13808/90

 

[Kglassner]

Thank you, I will try that tomorrow

 

[QBhoy]

Don’t suppose the regular maintenance involved a prop change ?

 

[Kglassner]

No it did not. It had been running great till a week or 2 ago

 

[Kglassner]

Well, I went and changed the fuel filter and it looked clean, no water in it. Also removed the spark arrestor and sprayed sea foam into the butterfly valve. Took the boat out and ran it. It ran great! Was getting 46mph @ 5200 rpms and rode smooth!
Not sure if it was the filter or just gunk in the intake.
Thanks for the info!

 

[TyeeMan]

Is 5200 R's a little high? Shouldn't WOT be 4800 rpm?

Maybe they bumped WOT rpm's a little higher on newer MPI boats, I don't know.

 

[alldodge]

^^ agree
Your tach is off, or your blowing smoke at us

 

[Kglassner]

The tach may be off but I'm just glad it's running better! I don't plan on running it wide open very often. Yes the max is 4800rpms

 

[QBhoy]

You should have hit the limiter at those rpm.