Re: throttle problem
Well, 7 mph is definitely slow, even 25 unless it's on a huge boat!
Before you do anything, a compression check is necessary to determine if the motor is good enough to even bother with. Compression check is done with the throttle wide open; all spark plugs removed and wires grounded (stick the plugs back in the boots and ground them); then jumper the yellow wire on the starter solenoid to battery red terminal. Watch the Prop as it's gonna spin!
If the compression readings are more than 10 psi different from each other, the motor's got internal issues and might not be worth messing with unless you want to rebuild it.
After that, you need to know if there's spark on all cylinders. If you have a timing lite, while the motor's running snap the lite around each spark plug lead and see if that cylinder is firing. If you don't have a lite, you can purchase a "firing indicator" from most auto parts stores. This little tool has a neon lite in it that lights up when placed on a 'hot' spark plug wire.
Now, just because it's sparking don't mean it's actually running on that cylinder.
To check this, turn off the motor, pull a spark plug wire off of the cyl you want to check, then take a spare spark plug, stick it in the boot and lay the spark plug on the block so it's grounded.
Start up the motor, if that cyl was working it'll sure sound different, if not, you'll notice no diff in running. You can also see if the spark plug laid on the block is firing, at least that gives you some idea of spark quality.
Something else you can do is, just lay your hand over the throat of the top carb, see if the motor stalls out, speeds up, or does nothing.
If it stalls out, it's probably running OK, you just flooded 2 cylinders by putting your hand over it.
If it speeds up, it's running lean and the carb probably needs attention.
If it does nothing, that means that the cylinders being fed by that carb are doing no work and you've got more troubleshooting to do.
In that case, and the tests show good spark, try spraying a mixture of fuel/oil with a spray bottle, into that carb and see what happens. If the motor picks up, that carb needs servicing since zero fuel is getting thru.
Repeat with the middle and bottom carbs and see what happens.
Beyond that, you've got to make sure that the distributor is turning when you advance the throttle, and that the throttle plates in all three carbs open up as the distributor is moving.
If you get nowhere after doing the above, you're probably gonna need a good service manual to get into Serious Troubleshooting Mode!
Also check out the FAQ's section of the forum, you should find some info there that'll help.
HTH & let us know what you find.........ed
