200 optimax intermittent stall & miss @ low rpm

[BBallFisherman]

OT273874, 2001 200 optimax, Ranger 619, Rev 4 17p

I've touched on this in a previous thread, however, it appears I likely have a separate issue. I have an intermittent stall on start up and slight stumble/miss in gear. Once given throttle beyond 1,000 rpm, it will be perfectly smooth. It typically occurs more frequently in warmer temps (>75 degrees). Also, when it occurs I have noticed that my bulb sometimes feels firm initially, like it is vapor locked, even if letting the motor sit for hours or days. Again, typically happens if exposed to direct sun or heat/humidity. Wondering if a failing pulse fuel pump wouldn’t have something to do with my issues. Usually performs better after long run, but recently had it stall after long run when idling to dock. Historically has not been inconsistent enough to troubleshoot but seems to be developing a pattern.

I always pump my bulb before every start. This has been on going since last year when I check thermostats (clean) and plugs (clean with similar burn).

Thanks

Matt

[lpugh]

OT273874, 2001 200 optimax, Ranger 619, Rev 4 17p

I've touched on this in a previous thread, however, it appears I likely have a separate issue. I have an intermittent stall on start up and slight stumble/miss in gear. Once given throttle beyond 1,000 rpm, it will be perfectly smooth. It typically occurs more frequently in warmer temps (>75 degrees). Also, when it occurs I have noticed that my bulb sometimes feels firm initially, like it is vapor locked, even if letting the motor sit for hours or days. Again, typically happens if exposed to direct sun or heat/humidity. Wondering if a failing pulse fuel pump wouldn’t have something to do with my issues. Usually performs better after long run, but recently had it stall after long run when idling to dock. Historically has not been inconsistent enough to troubleshoot but seems to be developing a pattern.

I always pump my bulb before every start. This has been on going since last year when I check thermostats (clean) and plugs (clean with similar burn).

Thanks

Matt

That is probably normal and a good sign, that means there are no vapors in there and the VST is probably full and the needle valve is closed not allowing it to overfill, vapor lock would cause the bulb to be soft and difficult to pump up
Is all the maintenance work up to date plugs, filters etc,
87 Octane fuel with Quickleen as well as 150-1 premium plus in the tank, this does make difference

[BBallFisherman]

Maintenance on plus and fuel filter is about 1.5 months past due. However, these symptoms have been exhibited well in advance of that. I began to notice them around this time last year. At that time I also checked thermostats for debris and those were also clean.

I agree on your comments with the bulb. If left in my garage, I can pump the bulb and come back an hour or so later and it will take about 1-2 pumps until firm. If left outside at the dock in heat/sun the bulb is sometimes already tight. Just seems unusual. VST needling sticking???? I’ve also checked throttle plate air gap with a 5/64 drill bit and it is a “snug” fit from what I can tell.

[EuropeanAM]

If you had a needle problem in the VST, you would have at least one other symptom (several possible ones, none of which you mention and you WOULD notice and mention them).

Since you're overdue for maintenance, and this developed (apparently) shortly after your spark plugs were replaced last year, I would suggest you get your maintenance up to date FIRST. Including new IZFR5G Spark Plugs, gapped at .032-.033", torqued to 20 lbs/ft.

NO force on any white portion of the spark plug (you must hold the hex portion while gapping, and use a tool that grasps the arm ONLY to manipulate the gap). Use a WIRE gap tool, via the "go and no-go method" (ie: .030" fits EASY, .034 or .035" will not).