Johnson 150GT VRO Help please

"Hello all! I just found this

"Hello all! I just found this board, and it seems to be full of helpful people who know their stuff. So here is my problem. I am somewhat experienced in auto mechanics (learned the basics in high school then practiced shadetree mechanics) but know nothing about marine engines, especially 2 strokes. I bought my first boat about a month ago. It is a 1990 model fish and ski with some cosmetic defects but seemed to be in good mech. condition. Basically a good "starter" boat for no more than I paid. I think the motor is also a 1990 model. The model # is VJ150SLESB if anyone an tell me for sure. When I looked at the boat it started quickly and idled smoothly with the muffs on. The first 2 times out, the boat ran fine. It started with no problem and each time went for about 2 hours with some low speed and some high speed cruising. I kept the original tank of gas which was about 3/4 full. Each time using it down to about 1/2 tank and refilling. The third time it again started right up and idled smoothly away from the dock. I got up on plane for about 15 seconds then started losing power and backed off the throttle. It cut off but started right back. It runs fine up to about 1/3 throttle then bogs down and will die if I don't back off. I checked the fuel line and filter, seemed to be clear. I pulled the plugs. They were all about the same wet with some oil on them. Not sure how much oil residue would be normal in a 2 stroke. I plan to replace them before going out again. Just looking for ideas on what to check and if it is the plugs, how to prevent it next time. Oh and also what sounds to me like a silly question. When I uncovered the carbs, there was no air cleaner! Should there not be one? Sorry so long but I wanted to give all the info I could."

Also forgot to mention that th

Also forgot to mention that the electronics on the engine were replaced about 2 years ago.

"There is no air cleaner such

"There is no air cleaner such as a air cleaner on a automobile. There is only a face plate.

Is it a case that the engine was running fine on this outing, then the tank ran low, you bought fuel, then when you continued to use it (same day), this problem popped up? If so, that would bring to mind contaminated fuel (water). However, this scenario should prevent the engine from running at all.

Did the engine sit for some time (Months) between the last successful run and the run where this problem popped up?"

"Thank you Joe for the reply b

"Thank you Joe for the reply but no this was the third outing in about a 2 week span. It has a 30 gallon tank which was about 3/4 full when I bought the boat. I don't know the condition of that gas but it ran fine. I used about 10 gallons on the first outing and replaced it with new gas. It ran fine the second time and I again used about 10 gallons and replaced it with new. The third time is when the problem came up. On the second outing it did run low on oil (low but not out, it still had a couple inches in the reservoir). There was a beeping sound. I assume this was a low oil warning because I took it in and filled the reservoir and the beeping stopped. But even during this it still ran fine. I thought about water in the gas also but it does run good at low speed and I bought the gas from the same place I have filled my cars for years with no trouble. I am wondering about the fuel pump. I also know that 2 stroke motors are bad for fouling plugs from buddies who had dirt bikes but not sure what I'm looking for with that."

For some reason it seems like

For some reason it seems like the engine does not get enough fuel.
Does it help pumping the primer bulb when it happends or does the bulb get 'flat'?
If a fixed tank - how is the tank ventilation -try running with the fill cap loose.
How is the condition of the anti siphon valve on top of the tank? (stuck ball-valve)