Long story... I'll attempt to summarize it without leaving out any information.
To start, it's a 1974 Mercury 650, 3cyl.
Last year, and carrying into this year, I was having intermittent fuel delivery issues, which I had been able to sort out in a number of ways... new primer bulb or lines, new tank, Seafoam (of course), etc etc.
I had a hard time with her earlier this year. When I finally got her started, I needed to keep squeezing the primer bulb. Changed the bulb, no improvement.
So, a while back I pulled apart and cleaned the carbs, and the only thing that really stood out to me was the needle valves were a little sticky. Freed those up, cleaned everything else, and and started puting everything back together. Gaskets all appeared to be in good shape.
No improvement.
Checked out the fuel pump diaphragm, found it to be in distress. Installed a new pump kit, and it ran great... once... before the same problem returned.
Pulled the carbs again. Gaskets sill looked good, but the rubber tip on the top carb's needle valve was torn up. Popped in a new needle & seat there.
I did not take on the bottom carb at this point. It's VERY easy to remove the top carb, and extremely difficult to do the bottom, so I left it as is to see if the top carb's needle would do the trick, and it did... then a leaf spring on the trailer broke.
The boat sat for a few weeks before I got to the spring, replaced it and took the boat out. It was in the low 40?s, and it took a while for the motor to warm up, but it ran great.
I ran it the one time, and a week later... more problems.
This time, it took forever to get her started. It would only run on full choke... it was idling very poorly, rough, blue smoke when throttled up, and an occasional misfire (a 'cough' if you will).
I didn't know where to start, so I changed the plugs and put in new, fresh gas/oil/seafoam.
The full choke problem was resolved, but I'm back to the drawingboard...
I have to keep priming her to keep her going, AND I have the occasional misfire.
I know the fuel pump is drawing fuel (disconnected the fuel line from the tank, pump IS creating a strong vacuum on the disconnected line)
I know I'm firing on all 3 cyl.
I'm going to check the compression tonight, but it does seem to be running well until it burns up the fuel in the bowls.
This is a learn-as-I-go process, so this is all new to me... Is it a good assumption that I prbably just have a fuel-line obstruction? Possibly in the bottom carb's bowl this time? Or is there somewhere else I should be looking?
I hate to pull that carb off again and end up finding NOTHING.
Sorry for the novel, but thanks in advance... I'm fresh out of ideas.
If you have questions, feel free to ask away, I should be able to answer them.
To start, it's a 1974 Mercury 650, 3cyl.
Last year, and carrying into this year, I was having intermittent fuel delivery issues, which I had been able to sort out in a number of ways... new primer bulb or lines, new tank, Seafoam (of course), etc etc.
I had a hard time with her earlier this year. When I finally got her started, I needed to keep squeezing the primer bulb. Changed the bulb, no improvement.
So, a while back I pulled apart and cleaned the carbs, and the only thing that really stood out to me was the needle valves were a little sticky. Freed those up, cleaned everything else, and and started puting everything back together. Gaskets all appeared to be in good shape.
No improvement.
Checked out the fuel pump diaphragm, found it to be in distress. Installed a new pump kit, and it ran great... once... before the same problem returned.
Pulled the carbs again. Gaskets sill looked good, but the rubber tip on the top carb's needle valve was torn up. Popped in a new needle & seat there.
I did not take on the bottom carb at this point. It's VERY easy to remove the top carb, and extremely difficult to do the bottom, so I left it as is to see if the top carb's needle would do the trick, and it did... then a leaf spring on the trailer broke.
The boat sat for a few weeks before I got to the spring, replaced it and took the boat out. It was in the low 40?s, and it took a while for the motor to warm up, but it ran great.
I ran it the one time, and a week later... more problems.
This time, it took forever to get her started. It would only run on full choke... it was idling very poorly, rough, blue smoke when throttled up, and an occasional misfire (a 'cough' if you will).
I didn't know where to start, so I changed the plugs and put in new, fresh gas/oil/seafoam.
The full choke problem was resolved, but I'm back to the drawingboard...
I have to keep priming her to keep her going, AND I have the occasional misfire.
I know the fuel pump is drawing fuel (disconnected the fuel line from the tank, pump IS creating a strong vacuum on the disconnected line)
I know I'm firing on all 3 cyl.
I'm going to check the compression tonight, but it does seem to be running well until it burns up the fuel in the bowls.
This is a learn-as-I-go process, so this is all new to me... Is it a good assumption that I prbably just have a fuel-line obstruction? Possibly in the bottom carb's bowl this time? Or is there somewhere else I should be looking?
I hate to pull that carb off again and end up finding NOTHING.
Sorry for the novel, but thanks in advance... I'm fresh out of ideas.
If you have questions, feel free to ask away, I should be able to answer them.
