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Hesitates on throttle up
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Author:  flaMtneer [ Fri Mar 30, 2012 7:19 pm ]
Post subject:  Hesitates on throttle up
There may be topics on this, but nothing came up in search - I've got a 99 Funship with a VP 5.7L Gsi/SX and a couple days ago after about 1.5 hours of tubing/kneeboarding it developed a hesitation when hitting the throttle from a stop. If I give it throttle quickly (normal quick accelerate) the engine sputters and there is a fuel smell like it's flooding. Once the speed/rpms are up it runs fine. Thought it might be gas (I'm running ethenol-free) so I put in 20 gallons and ran it again this evening - same thing and very consistent. If I baby the throttle I can keep it from sputtering, but anything other than really light throttle starting out will sputter.

Ideas?

Thanks.
Author:  Ccmblack [ Fri Mar 30, 2012 11:40 pm ]
Post subject:  Re: Hesitates on throttle up
I'm no mechanic, but could you be getting a vapor lock?
Author:  weather [ Sat Mar 31, 2012 12:55 pm ]
Post subject:  Re: Hesitates on throttle up
One of my engines started to hesitate on throttle when getting up on plane. It nicely occured at the same time my engine was operating cold (125-135 deg, it would not go to full temp ~165 deg). I 'sort of' fixed the issue by changing the thermostat. Now it will run at ~140 deg and no hesitation, still haven't figured out why it is running cold.

Anyway, point being is your engine running cold? Mine would get up to temp idling out of the marina, but at cruising speed would drop back down.
Author:  flaMtneer [ Sat Mar 31, 2012 2:06 pm ]
Post subject:  Re: Hesitates on throttle up
Thanks for the replies.

Vapor Lock - I've thought of that, but I'm not sure it fits my symtoms...but I'm not a mechanic either so....

Temp - No it wasn't running cold. Since it originally showed up after about an hour and a half of tubing/boarding I thought it might be related to something getting hot (thought the temp gauge was normal all day)...but yesterday evening when I went out it did it immediately after leaving the dock and the engine was cold and it continued to hesitate/sputter on every moderate and hard throttle the whole time we were out.

I googled around and there are many people reporting similar issues, but very few actual answers. I want to get this resolved as the boat has become a real PITA over the last 2 seasons. I bet last year I spent over $150/hr for the year. The boat's 12 years old and I'm anal about maintenance so I expect to have some stuff pop up and need R&R, but (literally) having an issue EVERY time out is getting really really old. We didn't enjoy it at all last season because of this and we're not off to a good start again this year.

Anyway - thanks for the opportunity to vent. :)
Author:  Walt [ Sat Mar 31, 2012 5:11 pm ]
Post subject:  Re: Hesitates on throttle up
IMO.. fuel. You are still running "winter gas" which has a lower flash point than "summer gas" blends. Try it again after the companies change the blends over for the season (should be in just a few weeks). Otherwise, you could check fuel pressure, and maybe replace your filter. But my money is on the seasonal changes, and unseasonably warm weather.
Author:  acguy [ Sat Mar 31, 2012 6:57 pm ]
Post subject:  Re: Hesitates on throttle up
I had the same thing happen to my sundowner when we first bought it. I noticed slight hesitation, then a few weeks later I lost the low pressure fuel pump. may want to have it checked.
Author:  flaMtneer [ Sat Mar 31, 2012 7:17 pm ]
Post subject:  Re: Hesitates on throttle up
acguy wrote:
I had the same thing happen to my sundowner when we first bought it. I noticed slight hesitation, then a few weeks later I lost the low pressure fuel pump. may want to have it checked.


I think this may be the most likely suspect. Fuel is another, but I put in 20 gallons fresh non-ethenol yesterday + fuel treatment. The fuel filter has maybe 10 hrs on it, so it's hard to believe that it needs changed again. I'm going to try to get it in to the shop next week, it's due for the yearly service anyway (not by the hour meter, just by date!!).
Author:  mibagge [ Sun Apr 01, 2012 6:28 am ]
Post subject:  Re: Hesitates on throttle up
I had the same problem with a 97 stingray, changed the water separater, Not sure if that boat has one. I'm no mechanic just a thought.
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