2000 mercury 40hp 2cyl 2 stroke running and starting problems

riverrat10 · #1 September 8th, 2008, 06:38 PM

I have a 2000 mercury 40hp 2 stroke 2 cylinder electric start and power trim. very hard to start. when it does start it runs horrible and smokes really bad (more than usual)and only at about 3800 rpms tops with muffs on in the drive way and will not idle. Sometimes it hard at first to start and runs and starts great the rest of the day. I have rebuilt the carb and checked the reed valves. valves are good. While running I unplugged top spark plug wire, it died. started back up unplugged bottom wire and it died. can someone please help me

achris · #2 September 8th, 2008, 09:30 PM

When you finish for the day, do you unplug the fuel line and let it run out of fuel? If so, that's why you're having problems... By running it out of fuel, you're filling the carb with oil, hence the hard starting and very smoky.

Dieing with either plug lead remove I would consider normal....

Chris........

riverrat10 · #3 September 9th, 2008, 05:50 PM

no. I leave the fuel line connected all the time.

skeporg · #4 August 28th, 2009, 11:47 PM

I have a 2000 30 HP 2cyl 2 stroke that sat outside for a few years. It fired right up, then stopped. Re-built carb. No joy. The problem was a cracked hose between the fuel pump and the carb. I also replaced all zip ties to prevent any air infiltration; but the cracked fuel hose was the culprit.

The smoke situation might indicate the oil injection system is bad. These things are supposed to fail on the rich side...so's to prevent mechanical parts damage. Sometimes it can be as simple as (again) a hose in the oiler system. Check and see if any are leaking. Replace instantly!

That said, they don't usually fail...