1988 90 V4 question

[moonman]

Finally got my boat out yesterday on Lake Erie. The lake was pretty flat and as I sped up, I moved the throttle handle all of the way forward. It was showing about 3600 rpm's and I was going about 28 mph. When I first bought the boat 3 yrs ago, I never came close to moving the handle that far and I was hitting 32 mph. Do you think it might be a carb problem? What do you think that the rpm's would be on this boat, 1988 16 ft Crestliner Mirage, at WOT? The motor seemed to run OK, but I thought it was weird that I could move the throttle all the way forward.

 

[Bosunsmate]

way to low rpm, check the link and sync, that the timing base is moving to its full advance and the carbs butterflys are horizontal at wot.
If thats ok, Then do a drop test

 

[SparkieBoat]

either your tach is not working properly or you have way too low RPMs. maybe too big of a prop. lots of things it could be. 4 mph speed loss could be many things also. the throttle should go all the way forward, I am not sure why it did not before. you may have something wrong inside your control box.

 

[moonman]

When I first got the boat 3 yrs ago, I took it out for a test drive on a calm day and I was going 32 miles and hour and still had plenty of room to go faster. I was just afraid to go any faster. Is their any kind of write up to do the link and sync? Do you have to be in the water to do it?

 

[moonman]

What is a drop test?

 

[SparkieBoat]

afraid to go past 32 MPH? that dont make sense. I go faster than that in my 14 aluminum boat. anyway, you surely have issues. you can follow the instructions in my sig below, maybe that will help you eliminate some things. right now with the information that you have given it could be anything.

 

[Bosunsmate]

What is a drop test?

pull off a sparkplug wire with insulated pliers off each cylinder in turn as the motors running in a bucket, the motor should drop by the same rpm per cylinder.
If it drops less for a cylinder that cylinder has issues