sport jet 90 help PLEASE

[ylw55]

Hey guys, i am new to this site and sport jets also. Heres the story. Two weeks ago I bought this 1994 sport jet and was unable to try it out because of the weather, owner said it run perfect, and it started great connected to water hose. Got it home and put it in the lake, it has no power, motor runs good just no power maybe 10 mph max. Mechanics around here do not want to touch it. I have cleaned the carbs, replaced the stator, spark plugs, etc. Compression is 140 on all three holes. Engine sounds like it is bogging under WOT. any help will be greatly appreciated, I am at my wits end.

 

[kend301]

Re: sport jet 90 help PLEASE

Welcome to I boats , Please post what kind of boat this is in and the engine serial number . A problem like this is very hard to diagnose if I can't hear the boat or see it run but I will give it a shot . Starting with a couple basics
1 be sure you have spark on all 3 cylinders.
2 Be sure you have the boat "in gear" so the reverse gate is moving when you open the throttle
3 check the reverse gate to be sure it is clearing the jet nozzle by 1/8 to 1/4 inch at WOT.
4 Check rideplate be sure it is not bent and sealed to the boat , no part of the gasket should be sticking out below the ride plate and no gap between ride plate and hull.
5 check intake grate for an obstruction as well as the impeller area .
6 disconnect the fuel line feed to the carbs and check fuel flow , does it pulse or flow smoothly ?
7 since you had carb work done are the idle air screws set to 1 1/2 turns out from lightly seated ?
8 pull the air box and see if the carbs are flooding .
9 Is timing set to 30 deg btdc at WOT?
10 try disconnecting the black / yellow wire at the rev limiter and test boat.

As you can see this can go in several different directions , real good idea for you to get cylmer manual # w815 so I can reference page numbers for tests and info you will need . Please answer all of the above so I can get some idea of which direction to go .

 

[ylw55]

Re: sport jet 90 help PLEASE

1 be sure you have spark on all 3 cylinders.
2 Be sure you have the boat "in gear" so the reverse gate is moving when you open the throttle
3 check the reverse gate to be sure it is clearing the jet nozzle by 1/8 to 1/4 inch at WOT.
4 Check rideplate be sure it is not bent and sealed to the boat , no part of the gasket should be sticking out below the ride plate and no gap between ride plate and hull.
5 check intake grate for an obstruction as well as the impeller area .
6 disconnect the fuel line feed to the carbs and check fuel flow , does it pulse or flow smoothly ?
7 since you had carb work done are the idle air screws set to 1 1/2 turns out from lightly seated ?
8 pull the air box and see if the carbs are flooding .
9 Is timing set to 30 deg btdc at WOT?
10 try disconnecting the black / yellow wire at the rev limiter and test boat 1. yes
2.yes
3. yes
4. not bent, no visible gasket or gaps
5. all clear
6. wiil check first today
7. yes
8. air box is stiill off and no flooding, however on a test run yesterday, small amt. of fuel from time to time coming from vent tube.
9. will check today.
10. when i replaced stator from red to black, the only way i could get fire was to disconnect black] yellow wire.

when i put the boat in yesterday, got past idle bouy, it took off and run strong, but it had a slight miss from time to time, so i pulled throttle back, and tried to take off again, this time no power, engine bogging.

the boat is a 14 Royale jet, i cant find engine serial number. it does not have a tach.
2

 

[kend301]

Re: sport jet 90 help PLEASE

Where did you disconnect the black/ yellow wire , at the switch box or at the rev limiter ? And is it still disconnected ?

 

[ylw55]

Re: sport jet 90 help PLEASE

rev limiter and yes still disconnected, is it possible this problem is in the switch box?

 

[kend301]

Re: sport jet 90 help PLEASE

replace the rev limiter , the brown wire interacts with the trigger and depending on how the rev limiter failed it still could be forcing cylinders to cut out . I do think it is a long shot that this is your entire problem but you need to replace it before something else shorts out because the rev limiter is bad.

 

[ylw55]

Re: sport jet 90 help PLEASE

i have a rev limiter here and will put it on today. the boat ran with the revlimiter and red stator, exactly as it runs now. mechanic friend found no ohms resistance on red stator, so the replacement was a black one that doesnt use the adapter module. when that was installed the engine wouldnt fire at all until i disconnected the revlimiter. he said he read somewhere that the revlimiter was only for the red stator? could this be true?

 

[ylw55]

Re: sport jet 90 help PLEASE

thanks for your help this morning. i found that the fuel pump diaphram had small hloes in it, replaced it not it runs like a top. it is a litttle slow to plane, do you think this may be the wear ring? Is this something that someone who has never seen the inside of pump could take apart and fix with jb weld? How would i know how thick to make the wear ring? would i just fill in the voids?

 

[kend301]

Re: sport jet 90 help PLEASE

What kind of boat is it in , these boats are slow to plane if that is your only problem left then get a set of smart tabs , call Greg at Nauticus 1-800-233-0194 and he will give you the proper part number to order . They make a world of difference .