[zariah]

I have a 1993 MX20 with a 5l/LX Mercruiser, 205 hp. After running on the lake for awhile and coming into dock for a nice meal with friends, I gently maneuver to the dock and the engine cuts out. Before I smash into a neighboring boat, the only way to get it started is to give it full throttle, CHOKE, then to idle so I can shift into reverse or forward, and she stalls again.(What the h... is he doing out there?) I had the idle moved up a smidge to see if that would alleviate the problem, but when that is done (idle increase) the engine has terrible post ignition and has run backwards sucking water into the cylinders and you are done.
So, any information on how to fix this problem of not being able to transition from a lovely day on the lake to a smooth docking experience of a clean operating engine that does not stall out when one shifts? What are the mechanism involved and is it simply a carburetor problem or are there other links involved?
Thank you,
Zariah

[il_Mio]

I had the very same with a new 3L Engine, whilst the engine being cold it ran great but once normal operating temperature, it stalled in idle. I adjusted the idle rpm (whilst engine warm) via a screw on the carburator to have the idle rpm according to the recommended idle rpm from the engine manual. In that way the idle rpm is now slightly higher in cold condition (choke open) than during the period I had the issue but at least in warm condition (choke close) it has the correct idle rpm and does no longer stall the engine when passing neutral.

Hope this makes sense and helps you.

Kindest regards,

Johan

[zariah]

Thank you. Makes sense and worth another try in the spring. I am not sure if the adjustment to the carb was done at full engine temp.
Zariah

[WetWilly]

Hi Zariah, it definitely sounds like a carb issue.

Except for cold idle and cold choke adjustments, all other setting should be made when the motor/carb are at normal operating temperatures.

I'll assume the carb doesn't need a rebuild so ...you mentioned that " the only way to get it started is to give it full throttle, CHOKE, then to idle so I can shift", do you have a manual choke? Having to use the choke leads me to think your motor is getting too little fuel at idle after it's been run a while (at normal operating temp). This could be due to the idle jets, choke or the fuel float being out of adjustment. I would also check for any vacuum leaks, as this willl cause a lean condition.

The last thing might be the timing, most Mercruisers require the disabling of the electronic advance in order to set the proper timing. If this is not done, timing will be on the retarded side all the way through the RPM band.

Good luck and let me know what you find that resolves your issue,
WetWilly

[zariah]

I do not have a manual choke, but I push the button on the throttle lever, move the lever full forward which I understands closes the choke valve across the air intake to give it full choke. It starts up right away, I retard the throttle, shift, stall... This is the way I often get it started as well when it is cold.
Anyhow, the carburetor has not been overhauled that I know of.
Thank you for all your information and I will bring it to the mechanic to see what he thinks. What is a reasonable price for a carburetor overhaul?

Zariah

[dwmax]

It could be your accelerator pump inside the carb, if the accelerator pump isnt working properly it stall while shifting into gear, the only reason why it doesnt do it at first is because the choke is acting like the accelerator when the motor is cold. If that is the case the carb will have to be rebuilt and cleaned. hope this helps and keep us updated.

[zariah]

Darrell,
Thank you for the suggestion. Makes sense to me and any idea what a re-build/cleaning should cost?
Zariah

[dwmax]

Normally a rebuild kit for a carb depending on whether or not it is 2 barel or 4 barel it should be between $60 - $100 plus the labor to do it good luck let us know how it turns out

[kenagdoug]

I had a friend that had the same problem...the Mariah would run great on the lake and then when he was in the no wake zone it would stall out at idle........he solved the problem by making sure he ran the blower and would even open the engine hatch a little to get more fresh air into the engine compartment...that seemed to cure his problem????

[Douglas Alderman]

I had a problem with my boat stalling in the no wake zones after being out all day running engine hard for a long time. I tied my boat up in a slip so the boat couldn't move. Let engine warm up to operating temp. Put boat in gear under load and reset R.P.M. for low speed idle, where it wouldn't stall out. Worked for me!