This motor has ran great for a while now, but suddenly has no power beyond say mid throttle. Runs great at idle and about to roughly midrange (no tach) but as you continue to throttle up you reach a point where it falls flat on it's face - doesn't quit running just bogs down.
It is a magneto motor, pull start, thunderbolt ignition, lightning energizer - 4 cylinder 50hp. Has a jet not a lower unit, but that shouldn't matter.
I'm thinking fuel or timing. I verified that the timing belt hasn't jumped a tooth or anything. messed with max advance screw and could not get a change in the problem. Verified that the distributor (magneto) is moving to the max advance stop screw as you advance the throttle.
Plugs were all fine but I wasn't able to check spark at all cylinders while on the water (and can't run a jet on muffs or in a garbage can!) but I will check spark and compression as soon I get time.
Fuel itself is fine - I ran another motor off the same tank to finish the weekend. no change in the problem if squeezed the primer bulb.
I replaced some fuel hose earlier this year and I'm curious if maybe it wasn't the right size? But come to think of it the motor ran fine after that change, so that shouldn't suddenly be an issue.
Are there any fuel filters besides the two screens - one at each carb fuel inlet? (I do not have a water seperator or filter inline in the tank to motor hose)
It doesn't really seem like an electrical issue (switchbox, coil, mag) to me - anyone think differently?
What else should I be checking?
It is a magneto motor, pull start, thunderbolt ignition, lightning energizer - 4 cylinder 50hp. Has a jet not a lower unit, but that shouldn't matter.
I'm thinking fuel or timing. I verified that the timing belt hasn't jumped a tooth or anything. messed with max advance screw and could not get a change in the problem. Verified that the distributor (magneto) is moving to the max advance stop screw as you advance the throttle.
Plugs were all fine but I wasn't able to check spark at all cylinders while on the water (and can't run a jet on muffs or in a garbage can!) but I will check spark and compression as soon I get time.
Fuel itself is fine - I ran another motor off the same tank to finish the weekend. no change in the problem if squeezed the primer bulb.
I replaced some fuel hose earlier this year and I'm curious if maybe it wasn't the right size? But come to think of it the motor ran fine after that change, so that shouldn't suddenly be an issue.
Are there any fuel filters besides the two screens - one at each carb fuel inlet? (I do not have a water seperator or filter inline in the tank to motor hose)
It doesn't really seem like an electrical issue (switchbox, coil, mag) to me - anyone think differently?
What else should I be checking?
