I bought a used 9.9 that was a great setup for my sailboat. It ran great when the guy sold it to me, but I've been having a few problems with it. I haven't been able to load test it yet. All of the work I've done so far is with it out of the water.
I'm long time shade tree mechanic. Lots of work on cars, before they got too computerized to work on, and a lot of small engines. I've worked on a few outboards, but I've only a couple of boats throughout the years.
Here is what I've done so far:
Cleaned the carb. It was a little dirty.
New fuel filter.
New plugs.
Checked the fuel pump. It is pumping and the carb doesn't seem to be running out of gas. It has had plenty of fuel in the bowl when I checked.
Replaced the CDI. That one hurt the boat bucks, but it cleared up my missing problem.
Ohmed out the the pick up coil under the flywheel. It was within norms.
I've got the motor running well enough. The problem I have is that when I try and idle the motor down it starts to surge. I don't have a tach but if I had to guess I would say a few hundred rpm or so. If I idle the motor up, the surge goes away. Again, I don't have a tach, but it feels faster than a 1000rpm when I get it to smooth out. It never misses when it surges up and down. It sounds almost like a governer that is hunting.
I also have a bit of hesitation off of idle. If I open the throttle, on the side of the carb, I get a bog and then it picks up rpms. If it were a car, I would say the accelerator pump had gone bad.
The motor runs, no load, well up through the rpm range. Nice and smooth, no missing or starving. I even, put the motor in a trash can of water to see if it was an exhaust back pressure problem. Same issues at idle.
I would like to be able to idle the motor down just a bit. I don't want to slam the gears with it spinning too fast, and a slow idle is useful when docking.
Any ideas on what to check next?
Thanks-
I'm long time shade tree mechanic. Lots of work on cars, before they got too computerized to work on, and a lot of small engines. I've worked on a few outboards, but I've only a couple of boats throughout the years.
Here is what I've done so far:
Cleaned the carb. It was a little dirty.
New fuel filter.
New plugs.
Checked the fuel pump. It is pumping and the carb doesn't seem to be running out of gas. It has had plenty of fuel in the bowl when I checked.
Replaced the CDI. That one hurt the boat bucks, but it cleared up my missing problem.
Ohmed out the the pick up coil under the flywheel. It was within norms.
I've got the motor running well enough. The problem I have is that when I try and idle the motor down it starts to surge. I don't have a tach but if I had to guess I would say a few hundred rpm or so. If I idle the motor up, the surge goes away. Again, I don't have a tach, but it feels faster than a 1000rpm when I get it to smooth out. It never misses when it surges up and down. It sounds almost like a governer that is hunting.
I also have a bit of hesitation off of idle. If I open the throttle, on the side of the carb, I get a bog and then it picks up rpms. If it were a car, I would say the accelerator pump had gone bad.
The motor runs, no load, well up through the rpm range. Nice and smooth, no missing or starving. I even, put the motor in a trash can of water to see if it was an exhaust back pressure problem. Same issues at idle.
I would like to be able to idle the motor down just a bit. I don't want to slam the gears with it spinning too fast, and a slow idle is useful when docking.
Any ideas on what to check next?
Thanks-