Power Loss when gears engaged

[pcvette]

I have a Yamaha 40 HP 3 cylinder outboard motor made in December of 1997. It cranks right up on the first or second pull. Idles perfect. Checked all the plugs and they have a very good spark. Checked gas lines, to all three carbs and gas is flowing fine. The problem is when I engage the prop, there is no power. Full throttle the boat doesn't even go 10 mph. Feels like I am towing an oceanliner behind me. Cleaned gas tank and abd I am using new gas. I even put Seafoam in tank hoping that would fix any gas issues. At a loss to what problem could be. Supposed to be going with friends and their boats tomorrow catfishing. Please help!! I have probably less than 50 hours on the motor since I bought it new in 1998.

 

[rodbolt]

Re: Power Loss when gears engaged

that low of hours usually indicates severe neglect.<br /> check the spark and compression, if its good clean the carbs and rebuild the fuel pump as well as checking the fuel tank for debris.<br /> the maint schedule has a calander as well as hours. how much has been done ?

 

[Texasmark]

Re: Power Loss when gears engaged

Following on rodbolt's suggestions...<br /><br />Fuel starvation is my first guess. Sea Foam should have loosened up your rings if they stuck and attack your fuel varnish issues too. Butttt<br /><br />If it idles ok you are using your low speed jets in the carb and when you try to go the high speed too. The other thing is fuel quantity. If all cylinders are starved, you have a fuel starvation problem at a common point...inlet fuel filter, fuel pump, fuel line, squeeze bulb (don't overlook a defective squeeze bulb).<br /><br />One test would be to squeeze the bulb at the same time you get into gear and try to go. If this helps it supports the fuel delivery problem in the fuel line, or fuel pump.<br /><br />Now if you are only running on 1 cylinder all of a sudden (when going into gear) that's another story and would be most confusing as to the mechanism responsible for that behavior.<br /><br />One last thing is that if you left fuel in your tank for an extended period, the pickup screen may be varnished over which would reduce the available fuel.<br /><br />Mark

 

[slapshotjh]

Re: Power Loss when gears engaged

try giving it some choke while its doing that. If it speeds up, clean the carb(s)