1991 150 Pro-V - Can't get rid of lean sneeze... Gesundheit!

iammarcuse

Petty Officer 2nd Class
Joined
Oct 15, 2007
Messages
131
I have a 1991 P150 TLRP. It has developed a lean sneeze at idle and will often stall after the sneeze. Otherwise it runs well and gets 5500 WOT. It does however occasionally stumbles while at cruise as well. Pulled the carbs and gave them a thorough cleaning... everything looked spotless. Filter clean, no water in fuel. Did a decarb with Seafoam as well. No change.
I found that if I pump the primer bulb the lean sneeze disappears. I checked the fuel vacuum and it was only 1"/hg at high idle. I replaced both fuel pumps and figured that would solve it. It did not. There does not appear to be any fuel restriction at all at least until up to the carbs. After that... always hard to tell. I set the pilot screws richer but 1/8 turn from spec and again no change. 1/4 turn... no change. Plugs are brand new. No anti-siphon valve. Spark test shows solid spark on all 6. At a bit of a lose here. Any ideas? Thx
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
9,116
Re: 1991 150 Pro-V - Can't get rid of lean sneeze... Gesundheit!

I would pull and clean the carbs better, maybe ultrasonic cleaning and then do the link and sync procedure like the service manual states
 

robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
Re: 1991 150 Pro-V - Can't get rid of lean sneeze... Gesundheit!

If it's a lean fuel mixture condition at 5500RPM's, then I'd say your motor is in real danger of frying a piston. Much better to get this corrected before a big failure. Maybe still some trash in one carb jet/passage? Good Luck!
 

iammarcuse

Petty Officer 2nd Class
Joined
Oct 15, 2007
Messages
131
Re: 1991 150 Pro-V - Can't get rid of lean sneeze... Gesundheit!

Thanks guys. Sort of what I was thinking too. Was hoping to avoid having to pull the carbs again since the boat is docked on an island. Always a challenge working on the water. Cheers.
 

erniefish

Petty Officer 2nd Class
Joined
Dec 11, 2007
Messages
153
Re: 1991 150 Pro-V - Can't get rid of lean sneeze... Gesundheit!

also, do not overlook the re-circ valves, i had a problem last year, i must of cleaned the carbs 5x, then found 2 bad valves, easy to check with some alcohol and a syringe, they are mini check valves, should only work one direction, good luck
 

iammarcuse

Petty Officer 2nd Class
Joined
Oct 15, 2007
Messages
131
Re: 1991 150 Pro-V - Can't get rid of lean sneeze... Gesundheit!

UPDATE:
Well, I too cleaned the carbs several times. To no avail. Over the winter I ordered 6 re-circulation valves and changed them. 5 of the 6 were non-functioning. Problem solved. This is a problem that is not even mentioned in the manuals. If anyone has a similar problem... check the re-circ valves.
Cheers
 

rowboater

Seaman Apprentice
Joined
Jul 22, 2006
Messages
35
Re: 1991 150 Pro-V - Can't get rid of lean sneeze... Gesundheit!

Thanks for the update.It's always good to know what fixes something when someone takes the time to post it.
 
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