Ox66 help

[Boatman2000]

2002 200 hp ox 66 , 1400 hrs . Need some help moving forward with motor running rough . Motor will shut of at idle after 4-5 minutes, increase idle and motor will stay running but after 4-5 minutes starts idling up and down by itself . Also , when trying to get boat on plAne 2will not exceed 3300 rpm needed to plane .i can ru. At low speed and one time it will plane out and run fine up to5100 rpm and the next time I try it will not get up on plane . I did spring maintenance including plugs,new filters, cleaned vst tank , o2 sensor . New thermostats . Since having problem I have done e following with no luck .

1. Changed all filters including external water separator, fuel bowl filter on motor , new vst hp pump filter, small screen filter on top of vst tank.

2. New primer bulb
3. Ran motor on external 5 gallon tank .
4. Remove check valve between engine fuel filter and low pressure pumps
5. Checked vacuum at low presume fuel pumps
6. 2 new low pressure fuel pumps
7. Checked fuel pressure at Scrader valve 35 with key on , 37 with motor running at all rpms .
8. Had injectors cleaned by the injector man .

I did all this after reading many post from many people on the Hull truth . I did post this info on their site without much response so I thought I would try somewhere else. I am almost to the point of saying Uncle! But thought maybe someone on this site can tell me if there is anything else to check before taking it to the boat dealer . Thanks for any help for the old man ,Greg

[99yam40]

I am sure someone with the proper knowledge will need the motors model # to start out with

[Boatman2000]

Thanks, model #SX200 if needed

[cpostis]

Thanks, model #SX200 if needed

Complete model # s/b SX200TXRA?

[Boatman2000]

Yes,SX200TXRA

[rodbolt17]

the procedure is
suck
squeeze
bang
blow.

lose any of the above and it quits running.

first we test compression to insure we can mechanically seal the cyl.

then we test spark, both spark PRODUCING components and spark CONTROLING components.

then we test fuel contoling components.
as a last resort check the ex for critters.
someplace between step 1 and 3 you will most likely find the issue.

\you will need a DVM with a DVA adapter and a fuel rail pressure tester and at least a tune-up spec guide.

[Boatman2000]

Thanks Rodbolt, compession is ,as has been since I bought boat. 120-125 on all cylinders . I have a craftsman Dvm , will get a DVA adapter. I have a fuel pressure tester that I hooked up to Scrader valve .Is this what I need or is a "fuel rail pressure tester a different tester? Also , where would I find a tune-up spec guide ? Thanks so much for you're advice , Greg

[rodbolt17]

they made the tune up spec guide till about 2010,then quit.
why?? I dunno.
I keep a copy of LIT-18559-84-05 on my desk.

about the only reasons a 2 stroke gasoline engine quits is it is out of fuel,meaning none in the intake manifold.
ya lost secondary compression-this wont come and go.
ya lost primary compression,this can come and go.
ya lost spark or the ability to control the spark timing.
the ex is clogged with wasps,dirt daubbers or the like.

that's the whole thing about troubleshooting.
step one is a thourough understanding of how the system is supposed to work.
second is recognizing what does not work.
third is why does it not work as designed?

makes it easier if you break it into subsystems.

[Boatman2000]

Thanks again Rodbolt, it only quits at dead idle after a few minutes of running, if I up the idle a little it will stay running , just starts idling up and down by it self ? Then if I have it in water it will not go above 3300 rpm . Boat needs about 3400 to plane out . Alternatly it will plane out and get up to5200 rpm which is about beast I have ever got out of it . But, even if it does plane out when I go back to idle it is rough and idles up and down by itself . We did have a lot of wasp. At storage lot this year , how do I check for clogged exhaust? Thanks again for yr time , Greg