Just a little throttle makes the engine sputter and die

[achris]

Like I said before, sounds like your choke isn't operating or adjusted properly.

Feels like I am talking to myself here!

Have a look at his other thread. Video shows the choke working perfectly.

 

[rderenzy]

SO! back from the bay - started backing off the mix screw like suggested - kept turning and turning, no benefit, must have turned a full 3 times
by the 4th full turn, It got better and better
must have made 6 full rotations (counter clock) and it was FIXED

or by that time was the engine warm so it was gonna be fixed? guess I wont know until next time

Played with the idle throttle - got the in gear idle down to about 650-700 later on the run

thanks for everyone's help - to be continued

 

[rderenzy]

Have a look at his other thread. Video shows the choke working perfectly.

yes, but I monkeyed with it to loosen it - it was not like that last night, the idle screw was way to tight, so when the throttle pulled it down, the choke was locked into place because the screw was too tight, it wouldn't auto pop back up - so a couple things in play here

 

[rderenzy]

You don't need to push it all the way forward. Do a test where you have someone look at the carb while you advance the throttle and see where it is when the choke closes.

this is what I don't understand, the choke is closed, always closed while throttle is straight up/Nuetral

 

[putback]

That choke is controlled by a coil spring heated by a electric element on the exterior of the carb. It rotates the axle the choke butterfly is on. Is the wire connected, is the terminal clean? if its working properly the housing its in should be very warm to touch after the engine has run about 2 minutes. If it is'nt working it would take about a half an hour for the engine to generate enough heat to reach the coil spring to fully open the choke. The elec element doe's the job in a couple minutes. It is also adjustable by loosening 3 screws and rotating it. Take out the 3 screws and look at the inside then you'll know how it works. No concern its a very simple system. If you are concerned about adjustment after removal. COLD engine, throttle partial open, [set at idle it will BLOCK the choke from closing] rotate element counter clockwise until choke butterfly just closes, tighten 3 screws. You may have to readjust a bit after a few hot cold cycles.

 

[Fun Times]

Also a video of my giving it some slight throttle here
https://youtu.be/ozNdA40X_U8
Any suggestions?

ah, yes i see, i have a button.

Now that you are aware that you have a throttle only advance feature by pushing in the button on the shift control handle.....Bearing mind that when you push that button in and advance the throttle handle forward, you are still in Neutral Gear which basically allows you to bypass the mercruiser neutral safety switch (no start in gear switch) so you can help set the choke by pumping/opening the throttle system on the carburetor to help ease the starting when cold...Which with one of your descriptions earlier, you didn't seem to have much of an issue with as the engine (used to? or still does?) starts right up without having to advance the throttle hot or cold which sometimes that happens too....But....It is also advised by Mercruiser that once the engine has started from cold, the engine should be slightly free revved (out of gear) up to as high as 1300 RPM in order to help excite the alternator to start the alternators charging system in turn ensuring the electric choke gets its proper voltage to start working faster.

After you've revved the engine up for a quick seconded, let the engine warm up for right around a minute time frame at right around 900 RPM +/- 100 RPM before bringing the idle down to 650ish RPM (< depending on engine temperature/working normal) and going into gear taking in the consideration of how the engine seems to be running before fully leaving the trailer/dock. The higher warm up idle RPM's will also help get both the cooling water and engine oil circulating properly too. New Flushing Procedure for Alpha and Bravo Engines When
Using a Flush Attachment on the Sterndrive

Now with all that mentioned, Before doing any other adjustments I'm going to suggest an easy test for you to try out. Since you know it does this at home (not in the water) but while in forward gear, when "you" know it's going to run bad like that cold, try using the advance throttle only button on the shifter and slowly rev up the engine like you did in the video and see if it still does that....Be sure you are not in gear/prop not turning for this test and let us know.

It's possible that your shift cables are now out of adjustment from R&Ring the engine affecting the Alpha shift-cut-out-switch mounted on the shift cable plate assembly mounted on the starboard side engine exhaust manifold assembly.

Also check to see if the nuts and washers that hold the shift cable to the plate assembly studs aren't supper tight. The nut's should be backed off one full turn so that the washers can easily spin by finger. Item numbers 9 and 10 connected to 13 are the ones to check to ensure they are not supper tight, http://www.mercruiserparts.com/bam/s...31523/1937/200

Good luck.

 

[rderenzy]

good info, i'll start doing that at start.
I never have a problem w/ the choke opening - if anything the choke opens too much or too soon

I found out yesterday - the problem i'm describing is better detailed with this.... boat runs great in neutral, it runs great while in gear nuetral, even giving it a slight nudge in gear, getting the boat moving slightly forward, no wake it runs great....it didn't do the bog until i gave it a little more gas

however, w/ adjusting the mixure yesterday, perhaps i fixed it - i'll know more tonight tomorrow when i take it back out

that is a DARN good test...tesing w/o in gear - i'll be sure to do that.

i'll also check the washer free spin, thanks for all of this info, its very helpful

I did find i think the idle screw was way to tight, when the throttle went down, it pulled down and forced the choke 100% open, and then since the screw was so tight it would STICK wide open, i would have to manualy w/ my finger force it back, just to close the choke

 

[rderenzy]

ITS Fixed !!!
Thank you @achris
That's all it was... Mixture screw....6 full fkn turns counter clockwise

Time for a new mechanic

 

[bruceb58]

If you had to turn your mixture screws out 6 full turns, I would suggest a carb rebuild or you have a leak where the carb mounts to the intake manifold.. There is no way it should require that many turns.

 

[rderenzy]

I agree.
I never had this problem until I took it to a mechanic for an oil leak
1,000$ later the boat leaks just as much oil... And now leaks water..:. And had this take off issue

 

[rderenzy]

Oh... Also... Why I think it was so out of spec... It was doing its stalling... I was on the water with the mechanic.... I said that stalling scares me....I asked if it wasn't idling high enough.... And I watched him turn that mixture screw until his buddy said the idle hit 9k rpm
After the last few days and research
Wow. What a lol

 

[rderenzy]

however - in the event that I turned the mixture screw back too much - how would I know? what would I look for