[mike66]

i took my boat out for the first time in the spring and tried to pull my daughter tubing - the motor starts fine and idles fine - my friend and i took it out and ran well - as soon as i tried to pull my daughter on the tube at 3/4 throttle it would die - i tried this several times and no go - my friend and i took it out again and it ran fine - i took it to a reputable marina in the kawarthas - they removed the vro, replaced the fuel pump, cleaned the carbs, replaced the spark plugs, went as far as to split the motor to replace the crankshaft gasket - no go - i watched the mechanic when he had the boat on the trailer in the water - he had it at full throttle and then sprayed gas into the carbs - each time he did this it would jump up to the next rpm's - i thought this was good not knowing much about motors he informed me this was not good - the marina has spent 6 weeks with the boat - he can't fix the problem - and when i brought it back it runs even worse - any suggestions would be appreciated

[djzyla1980]

If he sprayed fuel in carbs and it ran better... it's a fuel problem. Check for leaks in lines...cracked hoses, loose clamps. If that don't help try rebuilding carbs. Could be a clogged main jet

[mike66]

thank you for the reply we will be going up to the lake for labor day and i will check everything then - my neighbour on the lake has the same problem he to get his to the next level of rpm's has to push in the key (i will assume this is the electric choke) i tried this coming back from the marina and it did run full throttle - we both have 14' cadoretes with the same motor

[djzyla1980]

Pushing the key is priming the motor, hense giving the carbs more gas, Theres either a leak (meaning somewhere it is pulling air into the fuel-might not leak gas from that spot, but can pull air in) I would alost think that you have a leak somewhere in the fuel system. You are venting your tank right? If it was a clogged jet I don't believe that priming the motor would push enough gas through the clogged jet. As far as the mechanic goes...That is a good thing... You now know where to look for your problem.You can use grease on all the connections as a temp fix... if it runs fine with the grease on there then one at a time start wiping the grease off. When you notice the problem you you've pretty much found your leak.I haven't had to try this method, My fuel lines were hard and cracked so I just replaced them. But I have heard it works

[fishnfiend]

Yup, Dave JZ has it. Mine was doing the same thing (and would improve after pushing in the primer). Was crud in the main jet at the bottom of one of the carbs. On mine ('88 40 hp) you can remove the breather box, and pull a drain screw on the bottom front of each carb. If you have the right sized hose, then squeeze the ball from the gas tank, and flush the crap right out,there on the water. Also, on my engine, a medium sized safety pin just fits as a plunger through the clogged jet.Unfortunately, the jet is at the bottom of the carb - most likely to clog with any foreign matter that sinks to the bottom. Good luck!