I have had the following replaced on my 1998 Johnson 150 Ocean Runner. The VRO pump, All 6 Carbs have been Rebuilt, I have change the Fuel Lines from the tank to the engine and replaced the Primer Bulb, replaced the anti siphon Valve, Replaced the filters on the engine, replace the Racor Filter, checked Vent on Tank, checked suction screen on tank.
When I crank it up, its hard to start, I can turn the red lever on the Fuel Solenoid and it will crank up. While running the engin sounds and runs great. Once you get going, as the engine gets over 3000 rpms the check engine alarms, and if you run awhile the boat goes into safe mode.[:0]
If anyone could help please? 
Could the fuel solenoid be causing this? 
the VST on the front of the motor may be sucking air
you should be able to activate the fuel solenoid by pushing in the keyswitch
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Chris what is a VST and where is it on the front of the motor?
Chris I was looking on a break down and I couldn’t find the VST, isn’t that on a 4 stroke engine?
vapor separator tank
the omc have them on the carbed 2 strokes
its between the carbs behind the plastic intake cover
what is the model number of your motor J150???
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the vst is right with the VRO pump, the solenoid and the cone filter
there is a vacuum sensor there also
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Thanks Chris, you were very helpful…