F40 will not idle

I have a 2007 F40 outboard which I just purchased used in June...Saturday was the first time I put gas in the tank...(Lot of rain up here in Maine) Up until that time the motor was running fine...Now it won't idle down without stalling but high speed works great...Any ideas...Bad gas maybe,,E10,,Thanks

Won't idle

I have a 40hp motor. My engine had similar problem.
I changed out gas and filters.
Still same problem.
Brought it in the shop.
Said the Carburetors had to be cleaned.

Cleaned out and now it idles fine.
I just got the boat back last week.
Haven't taken it on the water to give it a Full test run.
But that was my problem. Dirty Carburetors.

[YAMAHAMAY]

Cleaning a carburetor - Same as Rebuild?

I have the same problem on my 9.9 2-stroke (runs fine at speed but won't idle).

The problem with mine was likely caused by water in the gas can - e.g. it worked fine until the gas tank had sloshed around for a bit. There is no question there was water in the tank. Now even the cleanest fuel can't get it to idle.

But I've never cleaned a carburetor (on an outboard). Does anyone know if somebody has posted a step-by-step on the process of removal, cleaning, and reinstalling?... and how I can get my hands on it?

Do I just follow the book and my good senses for removal and installation - clean the jets and everything else while I'm in there and just put everything back together again?
If all I'm doing is a good cleaning, do I need a rebuild kit or gasket set, or can I just put everything back the way it came apart?

[YAMAHAMAY]

I fixed my idle problem. This is what I did...

My 9.9 2-stroke wouldn't idle. It ran well at speed, but died when I tried to idle. Discussions seemed to indicate a carburetor rebuild. Ughh...

Fixed in 10 minutes!
But I fixed it myself with almost no effort (after a lot of reading, of course). No carburetor rebuild, no gasket replacement, no big engine parts had to come off. I didn't have to buy anything. Of course this won't fix idle problems in all cases, but it's worth the ten munites to try doin' this first.

I gotta confess, I now know I had water and junk in the gas can this spring, and I started up the motor before checking or cleaning the can. Problem! So I got out the manual and got online and started to read. I read about rebuilding the carb. I read about cleaning the low-speed jets in the carb - requires a teardown. But for me it's a big deal to rebuild the carb, or even just take it apart. I couldn't find much discussion on simply cleaning parts of the carburetor, although some people did mention it.

So I read the manual more deeply, then looked on this forum, and re-read the manual, etc.

In the end, all I did was...
1) clean the fuel filter
2) clean the pilot screw. Done!

Both the fuel filter and the pilot screw are easily accessible on the outside of the engine without taking anything off but the engine cover. If you don't know where they are on your motor, look in the manual under Fuel System and locate the parts by name on a diagram.

1) Fuel Filter - I cleaned the fuel filter by unscrewing it and blowing out the bits of dirt in the container and on the filter.

2) Pilot Screw - Then I removed the pilot screw, cleaned it off, sprayed carb cleaner into the hole and replaced it. This seems to have been the most significant part of the fix.

If you already know where all these things are on your outboard, this fix only takes 10 minutes.

The fuel filter (on my 9.9/15hp 2-stroke) is on the port side of the motor and has a clear container and a nut on top. Loosen and remove the nut, pull the filter unit away from the engine a few inches leaving the hoses all attached, and unscrew the container with the filter inside. Empty it out, spray out the inside with carb cleaner or compressed air. Pull the filter screen off and be sure it is clean, too. Put it all back together.

The pilot screw is on the upper part of the carb on the starboard side and has a spring on it to keep it place. Important! - Don't loosen this screw first! First you gotta screw it in and count the turns until it just stops (don't tighten it hard - it's a needle valve). Count the turns so you know how to put this screw back in the exact same position after you clean it. There's a table in the manual called Carburetor Set-Up Specifications and it says for my engine to back the screw off 1-1/4 to 1-3/4 turns. But when I counted the turns it was set to 2-1/8 turns - so I set it back up at 2-1/8 turns - whatever...
So anyway, after counting the turns, unscrew and remove the pilot screw, clean it, spray carb cleaner into the hole and replace screw. Turn it all the way in until it just stops, then back it off the number of turns you counted before you removed it.

And that's all I did. No rebuild, no carburetor removal, no gasket replacement. Nothing complicated. Nothing to buy. Just clean the filter and clean the pilot screw. 10 minutes!

Started right up. Idled just fine. I'm back on the water.

One note of caution! You might be tempted to do this with your motor on the boat and your boat in the water. If you drop any of these tiny parts, you're outa luck until you can get new ones. The 10 minutes I mentioned no longer applies.

Thanks to all who contributed bits of understanding on this forum.