Stall at idle

[OhTwoBu]

Crew,

After the first boarding pull of the day and the boat sitting in idle, the engine will stall out randomly. No stutter, just quits. It starts right back up and runs like a top the rest of the day. It's almost like clockwork: back off the trailer, idle out, throw a boarder in the water,pull for a few minutes, idle for a couple minutes then it stalls. Fires right back off and runs for the rest of the day like it never happened. Two straight outings it has done this. Thoughts? 2002 23LSV Monsoon 325. 350 hours.

[formulaben]

Are you still running some gas that had been sitting over winter?

[Jimmypooh]

When did you last replace the fuel filter? Have you checked the fuel pressure (free tool rental from any parts store)? Have you ever replaced the plugs, wires, and cap? Sounds like you might be due for some of this maintenance.

[OhTwoBu]

I just changed dizzy cap, rotor, fuel filter, plugs, wires, and cleaned flame arrester. Ben, perhaps so. I've ran three tanks so far this season but only filling up from about a quarter tank. Maybe there is some residual there. It's funny because its almost clockwork. It will stall after the first good pull of the day, then runs fantastic for hours. It is a very good running Monsoon.

[Jimmypooh]

I had a problem with my fuel regulator being clogged and causing too high of fuel pressure. Several others have had this problem too. Easy to check fuel pressure

[Woodshed]

Google idle control valve symptoms. Good chance this easy to change part is it. It was mine for similar issues. Auto part for mine was 35 vs 120 bucks for marine. Same part. 2 bolts.

[tacoma10]

Woodshed, do you have the part number for the auto version or the car you looked it up on?

Thanks!

[justgary]

Get some carb cleaner spray and shoot the throttle body before you start throwing parts at it. Make sure to get all the way around the butterfly and inside the ports and offices.

If you want to pull the IAC to clean it, that's even better.

[Jimmypooh]

You need some more diagnostics and evidence before you start throwing parts at it. Maintenance and cleaning are good though.

[Woodshed]

Tacoma,

No I don't. I went to O'Reiley's auto parts. They sell marine parts also. They looked up the marine version of it and then cross referenced the auto part. It went from, I think, about 120.00 to 35.00. I believe it was the Ford Fiesta part. I also was able to find it by "googling" the IAC for my engine and found that many others with the Mercruiser had found the same thing. The part number and car counterpart were online in some of my readings on various boat forums.

Also,,, the IAC can be cleaned and freed up for better performance. I was told NOT to spray carb cleaner into the engine. There is a "throttle body" cleaner that may be more approriate... or it may be the same I don't know... I was told it can deteriorate seals and stuff. You need to remove the throttle body and IAC to clean them I guess. When I replaced my IAC, I removed the throttle body and cleaned it.

Woodshed

[justgary]

True "carburetor cleaner" in the gallon can is fairly harsh stuff, and is meant for dipping stripped parts to clean them. The spray stuff is not the same, and is not nearly as caustic. I personally have no problem cleaning the butterfly and throat with the spray while the engine is running, but would only use the dip can for disassembled dipping.

It's up to you, of course, but the point is that it can look clean enough and still not run right. A clean throttle body (and associated parts) is the first step in diagnosing an idle problem. If "clean" means "replace" to you, that's a valid method, and I say go for it.

[Woodshed]

True "carburetor cleaner" in the gallon can is fairly harsh stuff, and is meant for dipping stripped parts to clean them. The spray stuff is not the same, and is not nearly as caustic. I personally have no problem cleaning the butterfly and throat with the spray while the engine is running, but would only use the dip can for disassembled dipping.

It's up to you, of course, but the point is that it can look clean enough and still not run right. A clean throttle body (and associated parts) is the first step in diagnosing an idle problem. If "clean" means "replace" to you, that's a valid method, and I say go for it.

I agree. Don't throw parts if a good cleaning is sufficient. Mine needed to be replaced as it was locked up. at 35.00 I wasn't about to clean reinstall only to find out it didn't work and start over.

Nice to know spray cleaner is easier on parts than dipping solutions. Makes sense... why would you need to spray it unless you were putting it into the intake??

Woodshed

Edited May 4, 2014 by Woodshed