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Merc 37 sputter backfire out carb still

H

hammeresq

Member
"Hey Guys,
I'm still hav

"Hey Guys,
I'm still having my sputtering / backfiring out the carb issue on my Merc 3.7

At lower RPM's, or under load the engine will sputter, stall and backfire out the carb. At idle and higher RPM's she runs flawlessly. When this problem first developed my Tach also went crazy, bouncing around much higher than the engine would be running.

Ignition stuff was changed last week (cap, rotor, wires, and coil). The plugs and points both look fine. The carb was rebuilt by a trusted marine mechanic last year.

At this point I am at a loss. I am thinking maybe timing, but that would not explain the boat running fine at idle and high RPM's.

Any help or ideas would be great!

Thanks,
Eric"
 
"I'm going down there this

"I'm going down there this week with my shiny new Craftsman timing light.

With respect to the timing, I assume the crank pulley is marked, is there an advance or anything else I need to account for? I've done this many times on cars, never on a boat.

Thanks,
Eric"
 
"I have a 165 hp 3.7 mercruise

"I have a 165 hp 3.7 mercruiser that won't start. New wires last year, new plugs today. There is no spark going to the plugs. I don't know how to set the distributer cap. Can anyone give me a crash course?

Thanks,
Bobby"
 
Bob:
You've hijacked Er

Bob:
You've hijacked Eric's thread. You need to start your own post to get the maximum responses.
Guy
 
"Sorry Eric,

I'm new to

"Sorry Eric,

I'm new to the site and realized my error after sending the post.
Good luck with your issues, I feel your pain.
Bobby"
 
"No worries!

Back to my bo

"No worries!

Back to my boat, I have heard that there are new timing specs for my engine (3.7) due to changes in fuel quality. Does anyone know anything about that, or have any other information about timing this engine."
 
"Problem solved, it was a coup

"Problem solved, it was a couple of things.

1) The points did not look as 'fine' as I thought they were. Replaced points and condenser, also cleaned out a small amount of oil in the distributer.

2) The timing was WAY off, used a timing light and got the timing set to 8 degrees before TDC (at the spec on the valve cover). Boy is she running great now!

Thanks a bunch for all the help! Enjoy the water this summer!"
 
"Eric..
about the timing, t

"Eric..
about the timing, the valve cover spec was changed on our engines to 4 degrees to make up for the " new" fuels being introduced, but, when i tried setting my twins to 4, they ran like sh*t, so i left it at 8 and mine too are running great and flawless, start almost instantly always and pull my 7700 pound 28 footer to 34mph, just thought ide let you know"
 
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