Merc 260 stalls at idle, carb flames back when engine stopped.

DJ Jaws

Seaman Apprentice
Joined
Nov 6, 2008
Messages
43
SO this one is particularly puzzling. Merc 260 4bl Rochester carb on a 1988 Sea Ray. At idle, it sounds like it's starving for gas. Runs good at faster speeds, maybe a tad pokey but it runs pretty smooth. However, when you idle it will be ok for about 30 seconds and then it will gradually slow to a stall. Then after a few seconds the center tube of the carb ignites like a birthday candle. Not an explosive burst like a backfire, just a slow burn like a birthday candle. And it doesn't go out. I'm worried that that flame could backtrack to the fuel line and cause a huge problem. Luckily this engine is still on the ground from a rebuild and not in the boat, but I'm trying to get it ready to go back in this summer. But fire is fire and is a huge problem.

I put a rebuild kit in the carb this spring, and I put a new baseplate on the carb. I'm wondering if there's something leaking fuel somewhere, or if there's a needle seat that's worn. Is this worth fixing, or should I just bite the bullet and put a new carb on this thing? Everything else is new, I guess a new carb is in order too? Thoughts and recommendations?
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
42,572
SO this one is particularly puzzling. Merc 260 4bl Rochester carb on a 1988 Sea Ray. At idle, it sounds like it's starving for gas. Runs good at faster speeds, maybe a tad pokey but it runs pretty smooth. However, when you idle it will be ok for about 30 seconds and then it will gradually slow to a stall. Then after a few seconds the center tube of the carb ignites like a birthday candle. Not an explosive burst like a backfire, just a slow burn like a birthday candle. And it doesn't go out. I'm worried that that flame could backtrack to the fuel line and cause a huge problem. Luckily this engine is still on the ground from a rebuild and not in the boat, but I'm trying to get it ready to go back in this summer. But fire is fire and is a huge problem.

I put a rebuild kit in the carb this spring, and I put a new baseplate on the carb. I'm wondering if there's something leaking fuel somewhere, or if there's a needle seat that's worn. Is this worth fixing, or should I just bite the bullet and put a new carb on this thing? Everything else is new, I guess a new carb is in order too? Thoughts and recommendations?

A flame on a carb :eek:, pull the carb and find out what's wrong or replace it. Something is leaking fuel but what is causing the flame to start? If it back fired this could start it but this was not mentioned. :boom: I would suggest to recheck your timing
 
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