Bad transition from slow speed to high speed!

vista4u2

Seaman Apprentice
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May 26, 2003
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Engine: '84 Mariner, in-line 6, 115hp.<br /><br />Hi guys... such a great forum this is. First of all it's a bear to get started, but my main problem is when I'm done slow speeding out of the no-wake area and go to throttle up, it acts like the carburetors are totally flooded out. My only remedy is go to throttle only, reve it up a few times to burn the excess fuel, and then feather it up and then it'll finally get going, and it'll run like a bat out of you-know-where. It will act like this after only 30 seconds or so of no-wake operation, or idling while waiting for a skier to ready up. It's like it's getting way too much gas at low speed. However, it will run at low speed nicely for a long time if needed, but transition to high is terrible.<br /><br />My fixes so far have been to adjust my mixer screws as lean as I can get them and still run smooth, remove the carbs, clean them and replace the gaskets, inlet valves and seats. I also adjusted the floats to close sooner as they fill up. This seems to have helped a little bit, but the problem is there. <br /><br />BTW - I mostly run this motor at a high altitude lake, 4000 feet above sea level. Can this affect jetting issues? Any help will be great, as this problem kills my babe magnet ski-ing options. Any help is appreciated. Thanks.
 

mellowyellow

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Jun 8, 2002
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Re: Bad transition from slow speed to high speed!

first I would make sure you have good compression<br />on all cyl. pump works off internal pressure.<br />I would also buy fuel pump kits and replace the<br />diaphram, gaskets and check valves.<br />good luck,<br />M.Y.
 

vista4u2

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Re: Bad transition from slow speed to high speed!

That's right, I had forgotten to mention that I have rebuilt the fuel pump. Compression is between 100 (lowest) and 110 (highest) on all 6 cylinders.
 

vista4u2

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Re: Bad transition from slow speed to high speed!

Yes sir, new check valves.
 

mellowyellow

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Re: Bad transition from slow speed to high speed!

hmmmm. tuff one.... r u sure float is not sticking? if you pump bulb, does gas leak out front of carb? sure sounds like it's flooding 2 me.
 

vista4u2

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Re: Bad transition from slow speed to high speed!

No, I'm not sure if a float is sticking, but I really don't see how it could be. Haven't noticed any fuel leaking out of carb when bulb is pumped. It pumps up to a solid feel with no excess fuel leaking anywhere (before I worked the carbs, fuel would be flowing out of a small jet the bottom carb's float side when engine running slow, but no more).<br /><br />I'm considering replacing my .078 size needle seats and valves to the smaller .065, and possibly rejetting the main jets 2 sizes smaller. Do you advise for or against this?
 

mellowyellow

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Re: Bad transition from slow speed to high speed!

my 1150 I6 sticks once in a while... a lil tap<br />on the side of the bowl with but of screwdriver<br />usually unsticks it.<br />willin to bet problem is in float/needle valve/seat.
 

vista4u2

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Re: Bad transition from slow speed to high speed!

Thanks for your help mellowyellow!
 

The Marine Doctor

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Re: Bad transition from slow speed to high speed!

Have you checked the restrictors inside the intake ports? They are plastic and melt away. They are needed for idle and for proper accel.<br /><br />Part num is 66517.<br /><br />These were placed in holes that are about 1/8 in...they are there to bleed the cyl's...they cut the size of the hole down to the size of a pen tip. If they are gone...they will flood the cyl directly below it. This will carry on until the fuel gets to the bottom cyl...and exits the motor.<br /><br />TMD
 

dvchristoff

Cadet
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Aug 2, 2003
Messages
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Re: Bad transition from slow speed to high speed!

This is from my Merc Manual, 1974 inline 6<br /><br />9. If engine hesitates during acceleration after adjusting idle mixture, it is to lean, and idle mixture shoud be richened slightly until the engine accelerates correctly.<br /><br />Also you are right at the jet changing altitude at 4000. That is you could go to the next smaller jet size and try that.<br /><br />Hope this helps.
 

vista4u2

Seaman Apprentice
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May 26, 2003
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Re: Bad transition from slow speed to high speed!

The Marine Doctor - That sounds like a very likely scenario. Not exactly sure where/what these small parts are (66517), but I'm certainly going to look into it. Thanks.
 
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