1985 Merc 350 /260 Vapor lock

Joined
Jul 4, 2007
Messages
7
Wellcraft Nova XL 1985 with metal fuel lines. Runs fine although I have stalling problem. I will run at different speeds with the blower on all the time and she will stall out. I wait for 15-20 minutes and she will restart and usally get me home however sometimes it will happen again and I need to wait another 15-20 minutes. I notice the Temp gage runs 200F at idle when not in motion however once under motion she will drop to 160F or below. I think I have a bad impeller in the lower unit that woud explain this however any ideas on why she stalls???? I have noticed fuel vapor coming from the carb and the air cleaner has shown black soot. Engine has 160 hours and look like a rebuilt or new carb was installed. Return fuel line looked plugged so I have removed this and will replace with new. Notice droplets in this hose. Fuel separator replaced and all gas removed and replaced with new. I have removed the fuel separator and did not find it full of water. Any help appreciated!!!! Love this boat as she is a tank in the water!!!!!!!!
 

dry dock

Seaman Apprentice
Joined
Oct 12, 2006
Messages
44
Re: 1985 Merc 350 /260 Vapor lock

I have a 79 470 that had a vapor lock -- installed eletric fuel pump it fixed the vapor lock issue.
 

SuperNova

Lieutenant
Joined
Mar 16, 2007
Messages
1,455
Re: 1985 Merc 350 /260 Vapor lock

It sounds like your fuel pump is weak or possibly has a hole in the diaphragm. When fuel pressure drops, it makes the engine more prone to vapor lock. Fuel pressure is what helps prevent the liquid fuel from turning to vapor when it gets a little warm. The problem is probably aggravated by your over-heating condition.
--
Stan
 
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