Johnson fast strike 150 rough idle

[Bassinbob47]

Hello. I'm new to iboats and I just purchased a stratos with a 1998 Johnson fast strike 150. My problem is a common one that I have read a
lot about on this website. When I first start it up it runs great, idles and planes out perfect. After running for a while and then shutting it off to fish for a while it will then run poorly right after I start it to leave. It will bog and stall several times and eventually clear and run OK but not great like it does the first time. I have just got it back from the repair shop. The mechanic fully checked the motor and found the needles in the carbs weren't clipped on correctly. Everything else is fine. He told me to run it and if it still does it then he would take a look at the vapor separator pump. I took it out the other day and the problem still exists. My question is, Does anyone agree that the VSP is what the problem is? I have also replaced spark plugs and water separator filter. Thanks for your time.

 

[Chris1956]

I have never heard a definitive cause for that issue. The closest guess anyone had was heat soak. Let me know if you get it fixed, and we can pass the fix along to whomever needs it.

 

[s.wxman]

+1. I have been chasing the same issue and just rebuilt the vapor pump and entire vapor sep assembly along with some work on the recirculation valves. Problem is better, but not completely gone. Today for instance I had only one restart issue while fishing in six restarts. The problem start was not after the shortest or the longest stop for fishing, but one of the middle length stops (20 mins). It was late morning, sunny, pushing 90 and humid.
Only one issue this morning, but it was still there. I am running out of things to check.
So, entirely possible the vapor sep is the problem, part of the problem, or none of the problem.

Good luck