Mariner 6hp 4stroke starting - whats normal ?

winsbury

winsbury

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My Mariner 2003 6hp 4stroke refuses to start if I follow the cold start instructions in the manual but with no choke it starts every time 3rd pull even from cold (even if left overnight outdoors on a tank in the garden.) Its just been fully serviced including full carb strip and clean, new plug , fuel filter, oil, tappets set etc etc. Once its started once it will start first pull thereafter, revs fine, no excess smoke and sounds sweet. Air screw adjusted to just keep it ticking over and throttle stop set so it just ticks over smoothly while in gear.

So, does the panel think anything wrong or am I worrying about nothing, its just that my older 8hp 2-stroke always started first pull but this engine is new (to me) ?
 
Tricky, if you know it will start every time with your starting method I would leave it. As a side note I've had an issue with my 4hp Mariner 4 stroke that it would keep flooding no matter how many times or who cleaned the carb. In the end I've replaced the carb with a new Tohatsu 6hp and it's transformed.

I'd run it as is for now and go sailing :)
 
Prime it, choke it and stroke it and she should start first or second pull.
Stroking the engine means pull she over slowly until you are on the compression stroke then release the starter cord, re engage the starter and give her a tug.
From your description though you appear to have a very rich mixture
 
The old plug was fairly sooty which was why I did a full carb strip and clean expecting that would sort it out.I havent run it long enough to see any deposits yet but the starting without choke made me think it was probaby still a bit rich though have no idea how to change it since I think mixture is down to jetting which is factory standard.
 
I like that method of mounting it with the very open well, our well is much more inboard so venting the exhaust relief is difficult, in fact I havent worked out how to do it yet with this engine as the relief ports are two tiny holes that wont readily take a bit of 8mm pipe like the older engine.
 
winsbury said:
I like that method of mounting it with the very open well, our well is much more inboard so venting the exhaust relief is difficult, in fact I havent worked out how to do it yet with this engine as the relief ports are two tiny holes that wont readily take a bit of 8mm pipe like the older engine.
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the outboard well was one of the reasons for buying a Minstrel. The prop throws water at the rudder so lots of grip. I can vector the engine so the boat will turn in its own length, impossible to drop the outboard overboard and it will also run with a short shaft - the downside is that it is bloody noisy

D
 
I had a mariner 4HP and a Tohatsu 5HP.Both 4 strokes. I found they both started with very little choke. Like Cliff says gently pull the cord until you are at a compression and let the cord back in, then a steady and long pull. Sometimes it would fire whilst I was finding the compression.
I wouldn't worry about mixture unless it causes you some grief.
If it's s/hand it may be someone has poked the jet out to clean it and inadvertently enlarged it. But it probably wouldn't idle nicely if that was the case.
 
winsbury said:
My Mariner 2003 6hp 4stroke ........

So, does the panel think anything wrong or am I worrying about nothing,
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It it starts easily, hot or cold, without choke, idles smoothly and runs well there not much wrong!.

It may be a bit rich. If you really feel you must tinker. Reduce the idle speed to an absolute minimum, screw the mixture screw in a little at a time until the engine is on the point of faltering then back the screw out again until it idles smoothly .... if necessary reduce the speed to keep it to a minimum while doing the adjustment.
Finally reset the idle speed to just idle in gear.
 
+1, lightly screw in the mixture screw as far as it will go, but do not over tighten it or the screw will get damaged, unscrew anti clockwise one an a half turns to give you a starting point. Screw in to richen the mixture and out to weaken.
 
Yes, certain that is the correct way. Think about it, unscrewing will make the mixture lean (more air), then if you removed the screw altogether the engine would stall as it would be sucking in too much air.
 
I thought it metered the fuel/air mixture through a gallery by-passing the butterfly.

From Marine Engine.com forum

Turn the mixture screw CCW 1/8 turn at a time to increase the richness of the mixture and let it settle for 30 seconds before doing it again. Start from 1&1/2 turns CCW from all the way CW.
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bikerbill said:
Yes, certain that is the correct way. Think about it, unscrewing will make the mixture lean (more air), then if you removed the screw altogether the engine would stall as it would be sucking in too much air.
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I'm not.

It admits a rich fuel air mix. unscrewing will admit more into the main air stream making the overall mix richer.
 
You lot are getting me confused now ;) Did a bit of checking, normally in most cases in to richen & out to weaken the mixture. However, it may depend on the design/make of the carb which may be the opposite way round, so best to check your manual just in case, though I can't find details in the owners manual for my 4 stroke Honda 2hp. Either way it is not that important just now. Firstly get the engine up to normal running temperature, then turn mixture screw in fully, turn out one and a half turns to get a starting point, turn out (or in) until you get steady high revs, then adjust the idle screw for a steady tick over whilst in gear. Your ears will tell you when the engine is running sweet.
 
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bikerbill said:
You lot are getting me confused now ;) Did a bit of checking, normally in most cases in to richen & out to weaken the mixture. However, it may depend on the design/make of the carb which may be the opposite way round, so best to check your manual just in case, though I can't find details in the owners manual for my 4 stroke Honda 2hp. Either way it is not that important just now. Firstly get the engine up to normal running temperature, then turn mixture screw in fully, turn out one and a half turns to get a starting point, turn out (or in) until you get steady high revs, then adjust the idle screw for a steady tick over whilst in gear. Your ears will tell you when the engine is running sweet.
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FWIW the instructions for setting the pilot mixture screw are, according to the w/shop manual, ( note the initial setting is 3½ turns!)

To lightly seat the screw then back out for 3 ±½ turns.

Start and run at a slow/idle speed in forward gear. Turn the screw in until the engine starts to lose rpm then back out ¼ turn and adjust for best performance.

NOTE Allow time for the engine to stabilise between adjustments. DO NOT adjust leaner than necessary to attain a reasonably smooth idle.
If the engine hesitates on acceleration readjust the idle screw

The correct idle speed is 1300rpm out of gear ,1100 rpm in gear.

The correct float level, when the carb is inverted is 9-10mm above the joint face, measured at the opposite side of the float from the "hinge"
 
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Yep, that's exactly how I set it up so I guess alls well, perhaps its just not cold enough yet to need choke. Thanks for the help everyone.
 
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