2001 Mercury 3.3hp 2 cycle, I'm stumped over fuel/air mixture problem, rebuild carb?

Todd RT · #1 April 4th, 2009, 02:23 PM

I have a 2001 3.3hp 2 cycle outboard. It has very few hours on it. I've always ran the carb dry before storing.

First it was not idling well, figured the carb was dirty... found the fuel bowl gasket was done, letting air it. Took the carb apart, looked clean as new. I could see right thru the main nozzel, looked super clean. Replaced the fuel bowl gasket, started right up and idled like new!

Figured I had the problem licked, took the dink for a spin, and at full throttle, I have to close the choke about 1/2 way.

Now I deducted that the engine must not be getting enough fuel, tried to adjust the idle screw, figured it would help... but it only adjusted the idle.. go figure.

This morning, I took the whole fuel system apart (not the carb), the tank filter was clean, the fuel cutoff switch seemed to be clear (blew air thru it), same with the fuel line.

Back to the same, needs to have the choke closed halfway to run, and if I open it up all the way, the engine bogs and the exhaust gets smokey... close the choke 1/2 way, runs great. (THIS IS ALL AT FULL THROTTLE, idles and runs low speed fine with the choke all the way open)

I feel there are 3 things possible...

1. I should just buy the rebuild kit for $35 and soak the carb and rebuild.
2. Could it be the fuel cutoff switch not allowing enough fuel?
3. Maybe I need to ajust the float arm?? Is this something that needs to be adjusted?

Thanks in advance for any help. I'm obviously a rookie 2 cycle guy.

Laddies · #2 April 4th, 2009, 03:04 PM

A couple things if you open the enrichment lever(choke) and it smokes thats to much fuel not enough. Did you checl the idle jet tube to the foat bowl as it supplies fuel not only at idle but a bout 30% at high speed. Remember that the igle screw richens in and leans out. I don't think the float level has changed inless you tinkered with it.

Todd RT · #3 April 4th, 2009, 03:21 PM

Laddies,

Thanks for the quick response.

I looked at the "Inlet valve needle", but now that you mentioned it, I didn't remove the "idle speed screw". I would assume that is where the idle jet tube is?

But if it's too much fuel, the idle jet should be clear anyways, right?

Todd RT · #4 April 5th, 2009, 09:35 AM

Bump!

??

Laddies · #5 April 5th, 2009, 10:04 AM

Todd, you need to take the carb apart and clean it they may look spotless but with todays fuels some varnish is impossible to see the jets must be rodded out or checked for size with a sizing rod or replaced. The air/fuel passages must be blown clean with carb cleaner. If a fuel flow diagram will hell I can send one.

Todd RT · #6 April 6th, 2009, 08:13 AM

Got it!! I told you I was a rookie @ these 2 stroke motors... but after reviewing the diagrams of the carb (http://www.crowleymarine.com/mercury_parts/4665/40.cfm)
, reading on these forums... especially the FAQ's..

I found that the "main jet" had a little corrosion (from non use.. not varnish) on the inside of the hole. Wasn't much, but enough to slow the fuel flow.

Thanks again everyone!!!