90 150 gt idles great nothing over 1100rpm.

[chris71167]

I got this boat with unknown history and done a ton of work to it. All work was done according to the factory manual. took it out today. starts right up runs super smooth. in idle and in forward when throttling over 1100rpm feels like it trying but bogs will not die unless throttle is left there.

Ive replaced/checked . compression 95 all cylinders. ran seefoam in gastank/new gas. decarbed motor. new plugs/ coils/fuel filter/power pack/ port side temp sensor/water pump / all new fluids timed, link and sync. carbs rebuilt with new floats and adjusted/ fuel pump screens/ vent screen and pickup screen clear, bulb is fine. the only thing i noticed is during all this testing and repairs was before i put the power pack on it would go to 2500rpm and run fine. so i swapped the old power pack back on and will test tommorow. ANY other ideas?

 

[dehydrated]

Re: 90 150 gt idles great nothing over 1100rpm.

just wondering what your jetting is idles mids and mains? phil

 

[emdsapmgr]

Re: 90 150 gt idles great nothing over 1100rpm.

Sounds like the idle passages in the carb bodies are clear. Not sure if the mids and high speed jets are functioning. When you cleaned the carbs, did you pull all the jets and inspect them for debris/dirt. Also, did you clean all the passages in the carb bodies with an aerosol carb cleaner? Check for strong spark on all 6 plugwires with a spark checker or inductive timing light. When it starts to bog, try constantly priming the fuel hose bulb-that will force extra fuel into the cab bowls. If that works, you may have a weak fuel pump. That engine should have the S.L.O.W. system, which will limit rpm's to 2500 if the engine thinks it is overheating.

 

[chris71167]

Re: 90 150 gt idles great nothing over 1100rpm.

Not sure about the jets it has what ever was stock in there cleaned everything spotless with carb cleaner and air gun. Pumping the bulb does not help. Already went threw the whole slow mode diag replaced a temp switch and powerr pack. Did not remove jets but did clean the crap out of the carbs really really spotless they weren't that dirty also. Runs fine in driveway reving up a bit. Just bogs after 1100 with a load

 

[chris71167]

Re: 90 150 gt idles great nothing over 1100rpm.

So took it out today with old power pack same results, exept I noticed I was jacking with the trim and throttle and it felt like something broke free now it all the sudden runs up to about 2500rpm with no problems runs perfect now it won't go past 2500. I also noticed today if I pump the bulb it doesn't do anything no better no worse, a couple times it felt a little soft while running. Also is this considered the anti syphon valve? If not were is that located. I'm also going to recheck the slow mode. Any help would be appreciated thanks