342 Help

Wildboating

So I just bought our boat 3 weeks ago and found tons of problems when I got it home.  Longstory short both port and starboard motors had dead cylinders and ran rough.  We have tore down both motors and rebuilt top end with new valves, machine work and injectors.  I had #5 cylinder on both engines were 25psi starboard, 8 psi port side because tuliped valves.  All others were 125psi.    Either way, just finished getting it back together however the starboard motor still stops producing power around 3500rpm,  the boat will run right up to it and just stop or the throttle will make power till about 3/8 and there is no difference from there to wot.  Any ideas, no alarm.  Port side seems to be fine, she will scoot to 4000 with half throttle and plenty of torque / power with each tap of the throttle.  I don't want to run them that far out of sync so 3500/4000 is the best i have seen yet.   Starboard gimbal bearing seems to have taken a dive, could the knock sensor be picking up the noise and retarding the engine?  Anyone in Cleveland Area with a Rinda Scantool?   

Wildboating

03 350 Mag Mpi bravo 3 with factory props

Handymans342

Have you checked the fuel pressure? 

Wildboating

Engine revs fine with no load, will not exceed 3500 with load though

Weber

I assume you are the same guy on facebook with the same problem?

check the fuel pressure under load, and try the running off the hood running motors fuel tank.

Most likely a fuel problem has been your issue all along.

raybo3

Maybe a throttle cable adjustment?????

Black_Diamond

Are you SURE the props are the same on both sides?  The pitch is embossed into the outside of the prop hub.

raybo3

Hey BD wouldn't the boat "pull" to one side if the props were different??? 

Black_Diamond

You would think. I put it out there as a thought since there seems to be aot of problems on that boat. Easy check!

Wildboating

I am the same person on FB posting.  The props are to the best of my knowledge the same, I am having the boat hauled out tomorrow to yank the drives and throw new gimbal bearing in and will confirm for sure.  I just purchased a Rinda Diacom system that will help provide some insight.  I will also be checking fuel pressure, I am not real certain where the problem lies but it is getting very frustrating driving a boat that struggles to hit 30mph.

Weber

Did you try running the engines off one tank?

Black_Diamond

Tuliped valves are from the engine lugging: over propped. My 03 came with 24P props and was a dog at best. Dropped to 22P and all the difference in the world. 

Wildboating

Not yet Weber, Had family thing this weekend.  

Wildboating

Black Diamond,
I don't anything about propping, does a lesser pitch give more hole shot or top end?

JC290

lower pitch better hole shot less top end 

Black_Diamond

Too much pitch and you'll lug the engines and it will be a dog out of the hole. At 24P and 4 adults on mine good luck getting on plane. 22P problem solved.