Hello Guys, I am completely stumped and need help
Badly
.
I have a 18hp Mercury 1981 model that I've been running for ten years with no issues. Been in the family since new. Since its first outing this year which was a slow 4 hour trip just above plane, the engine will not start without manually opening the butterfly and will not idle. It starts fine then and runs smooth to WOT, however it seems to run and shake at low RPM. Also I'm noticing lots of carbon and sludge from the exhaust.
Here are things I've done, and checked
1. New fuel tank, bulb, lines, clamps, connectors, filter, and verification of correct flow.
2. New NGK BP8HN10 plugs (as always)
3. Fuel pump kit
4. Carb and gasket kit.
*this did not include a float or needle and seat nor main jet which is NO LONGER AVAILABLE*
I have inspected main jet and replaced o ring. I have found a used carb from a 25 hp and used the float and bowl off it with my main jet. This looked to be in great shape.
5. Checked timing
6. Sprayed all the seams with soapy water to try to find leaks.
7. Adjusted low speed jet from 1-1/4 turns to 2 1/2.. I've been running it at 2 for years..
8. I've always speculated the enrichment valve to be the issue but it seems to be sealing okay.
9. The motor will run with #1 cyl unplugged and vice versa with #2.
10. fresh fuel with 50:1 mix.
So, PLEASE HELP. I NEED LAKE THERAPY.
Badly
. I have a 18hp Mercury 1981 model that I've been running for ten years with no issues. Been in the family since new. Since its first outing this year which was a slow 4 hour trip just above plane, the engine will not start without manually opening the butterfly and will not idle. It starts fine then and runs smooth to WOT, however it seems to run and shake at low RPM. Also I'm noticing lots of carbon and sludge from the exhaust.
Here are things I've done, and checked
1. New fuel tank, bulb, lines, clamps, connectors, filter, and verification of correct flow.
2. New NGK BP8HN10 plugs (as always)
3. Fuel pump kit
4. Carb and gasket kit.
*this did not include a float or needle and seat nor main jet which is NO LONGER AVAILABLE*
I have inspected main jet and replaced o ring. I have found a used carb from a 25 hp and used the float and bowl off it with my main jet. This looked to be in great shape.
5. Checked timing
6. Sprayed all the seams with soapy water to try to find leaks.
7. Adjusted low speed jet from 1-1/4 turns to 2 1/2.. I've been running it at 2 for years..
8. I've always speculated the enrichment valve to be the issue but it seems to be sealing okay.
9. The motor will run with #1 cyl unplugged and vice versa with #2.
10. fresh fuel with 50:1 mix.
So, PLEASE HELP. I NEED LAKE THERAPY.