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oldskier

2005 Monsoon running issue

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oldskier

I hope someone can help here. Saturday, after a full day of skiing etc in 90 degree temperatures, 8:00 am to 3:00 pm, I put the boat up on the lift. It had run perfectly all day without a hint of a problem. I periodically check the guages and the temperature gauge never budged off of operating temp. Less than 2 hours later we wanted to go skiing again so I lowered the boat. The engine turned over and actually started but it didn't sound right, coughing and sputtering. I put it into reverse and it stalled right out. Tried a number of times to start it and put it into gear. It always cranked and started but never ran for more than 10 seconds but not at idle speed. If placed in gear it acted as if it was in neutral.

Let it sit on the lift all night. Sunday morning when I went to put it on the trailer it started fine and ran as if nothing happened. It is on the trailer now. This has never happened before.

In April the boat had a complete tuneup including a new fuel filter and the fuel injectors checked. I supposed a fuel supply issue is the most likely cause but would it correct itself overnight like that? Do these enginges ever get vapor lock that may explain the situation?

Thanks for any advice.

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Bill_AirJunky

Vapor lock. E10 gas. Heat soak. All not uncommon issues that you can find multiple threads on here where people describe these issues. Chances are pretty good that you could have popped the engine cover & let the engine cool off a bit & it would have run fine.

Just a guess. YMMV

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wakedv

I had the same problem on the weekend, it would start and idle rough, put it in gear and it would stall. popped the engine cover looked for anything out of the ordinary. tried it again and away it went. Thumbup.gif

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oldskier
I had the same problem on the weekend, it would start and idle rough, put it in gear and it would stall. popped the engine cover looked for anything out of the ordinary. tried it again and away it went. Thumbup.gif

No such luck for me. I did the same thing looking for loose wires, hoses etc. I even started the engine with the cover up but it did the same thing. I'm hoping it is vapor lock. Taking it in to hook up to the computer to see if the engine threw out and error code.

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WakeGirl

If it was heat soak/vapor lock, it would take a little bit with the engine cover up to get it started. In that situation it needs to cool down, so some cool damp towels around the fuel lines & rails probably would have been a better remedy.

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Baddog

What is the temperature guage reading? Could you have weeds blocking the screen on the infeed side of your tanny cooler? Happens a lot and the engine would get hotter than the normal 160F.

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mellen_mpz

mine has done the same thing a couple times.....but its been in temps above 115. We open the engine cover and it starts up pretty quick

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oldskier

I periodically scan the guages while driving. The temperature guage stayed at operating temperature. I guess I'm still leary about the vapor lock explanation because it sat on the lift for close to 2 hours. Wouldn't that be enough time for the lock to dissapate?

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WakeGirl

In that heat with the engine cover down, no. There were times when we would come home from the lake, put the boat away for the night, & I'd go out the next morning & the engine would still be warm. The engine cover does a great job of insulating noise, but it also holds heat.

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JBuck

My boat started acting that way... It was intermittent at first and progressively got worse the more and more we took it out. I too checked all the possible culprits. Vapor lock - no, Loose Wires - no, Tranny screen - nope, and thought well, what could this possibly be??

This past Friday I changed the oil which really didn't need it... Changed the plugs, cap, rotor, and fuel filter. Also took the lines off of the fuel pump top and bottom and cleaned it vigorously with carb cleaner. Stopped at the gas station to fill her up before the lake and added a bottle of STP injector cleaner with the fill up and headed to the lake. Ran perfect all day long, starting, stopping, back to the dock for a quick lunch and back out on the water without a hitch! Thumbup.gif

I would have never thought to change all those things because I just did it all except the cap, rotor, and plugs at the beginning of the season. My boat has the Monsoon 340 and had 138 hours when I did the work on it. Lesson Learned?? When in doubt, change everything even if you think you don't need to and chances are you'll catch a piece of the problem and giving a starting point.

Also need to point out that without the help of this site, I would've never thought to take the lines off of the fuel pump and clean them out... Thanks TMC!!! :werule:

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oldskier

Thanks for all the suggestions. I'm fairly confident that it had to be vapor lock. Over 580 hours on the engine and this is the first time I've had this problem. Must have been a unique set of circumstances.

I took the boat out yesterday morning and ran it. Of course it was 20 degress cooler and less humidity but I accelerated it hard from 0 to 40mph about 10 times. No problems. Smooth, fast, acceleration with no hesitations. At idle the tach stayed solid at 650rpms.

Lesson learned is to open the engine cover after it has been run for awhile when we might be using it again in a couple of hours.

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h2oskidude

I would be interested to hear from people having the hard hot start problems on monsoons 340's. Next time try and pull the pin to disengage the transmission and push the throttle 1/2 to 3/4 down like you would do for a flooded start and see what happens. I have been able to get mine started this way but I also did some further checking and found that I have 3 cylinders with compression below 85psi. I have been running 100 octane aviation fuel.

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h2oskidude

I would be interested to hear from people having the hard hot start problems on monsoons 340's. Next time try and pull the pin to disengage the transmission and push the throttle 1/2 to 3/4 down like you would do for a flooded start and see what happens. I have been able to get mine started this way but I also did some further checking and found that I have 3 cylinders with compression below 85psi. I have been running 100 octane aviation fuel.

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BlastRlxi
I would be interested to hear from people having the hard hot start problems on monsoons 340's. Next time try and pull the pin to disengage the transmission and push the throttle 1/2 to 3/4 down like you would do for a flooded start and see what happens. I have been able to get mine started this way but I also did some further checking and found that I have 3 cylinders with compression below 85psi. I have been running 100 octane aviation fuel.

Why?

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