joshuamanning
New member
2000 Yamaha 200 V6 2 stroke Saltwater Series II- compression 110-112psi across 6 cylinders- carbureted motor- (non OX66)
So, starting from scratch, last year (7/15) i was taking a cruise one evening and (have never had an issue with motor-flawless performance) i hit a choppy part of the river and all of a sudden the motor drops power like its out of fuel(3/4 tank) drops like 800-1000 rpm and starts cycling between running good for a second then dropping rpms like its running out of fuel. I turn around and head back to ramp, take to local reputable certified yamaha dealer and describe issue. They change the fuel pumps and say "its running great"(on muffs albeit).. so i pick up the boat and take it out and its doing the same thing only its dropping(stumbling) 3-500 rpm in a chop for a few seconds then picking up and running ok for 1 or 2 secs. So i carry back and describe the deal and they say its the carbs need rebuilt. So i have them rebuild the carbs and they say its ready, so i pick it up... get out and run it and once i hit the chop(1'-1.5' waves) it starts again.. only its dropping 200 rpm for a sec and then jumping back up and running fine, then dropping 200 etc...stumbling enough to notice the loss of power- and i smell fuel. At this point i shut off the motor, pull the cowling and there's fuel dripping out of the bottom of the airbox/breather so i crank it and the fuel begins pouring out of the breather box... soooo i swing around and head towards the ramp, return the boat and describe everything and show a video clip of what its doing(including the fuel pouring from airbox/breather) starting to get a little frustrated. (each time i take boat back they put it in line and it takes a week to get the boat back).. i also ask them if it could be a coil pack or electrical and they say no, that all the coils checked out ok... they say i needle and seat was bad(after a fresh rebuild???) so they fix the needle and seat issue- i ask them to take the boat out and trial test it politely, which they do and also carry an aux tank. They return and say the problem is a crimped fuel line at the lower cowling inlet grommet(where all the lines enter the motor) well, i had them replace all the fuel line from tank to onboard filter on motor/external micron filter/bulb/fuel tank bulkhead fitting with check ball/pickup tube in tank/screen on pickup tube/...(all brand new stuff complete from tank to motor).. soooo, i didn't ask them to trial run after replacing all that because i figured that would do it... well, a week later i was able to take the boat out and it happens again... 200 rpm drop in chop. at this point i have my wife drive the boat and i start pumping the bulb while its stumbling.. at this point the added pressure (from the bulb being pumped) the engine picks up 300 rpm and runs awesome as long as I'm pumping the bulb.. so once the water slicks off everything runs great again..so i get the idea that I'm losing fuel pressure from lack of ?? vacuum? maybe? i get back to my house and double check everything the mechanic did (i am a decent mechanic but not an "outboard" mechanic) so i know enough to double check all the hose clamps and even put 2nd hose clamps on everything to ensure for secure fits.. go back to the river and same thing... 200 rpm drop. At this point i put my own idea in place, an inline fuel assist pump making 2-3lbs of pressure. wire it in with fuseable link and heat shrink and head to the river.. same thing... i pump the bulb and it picks up the pace and runs fine again..hit the chop and it drops 200 rpm again.. soooooo.. here we are a few months later coming up on a years worth of waiting and tinkering and i figured id run this story by the field of experts and see if this sounds familiar.. any ideas would be appreciated.. i am now considering an inline pump with a regulator and dialing the pressure to whatever a squeezed primer bulb would be (10-13lbs?) and seeing if that corrects it? or checking the float settings? again if it didn't run perfect when i pumped the bulb then id be thinking electrical.. but it straightens out once i pump the bulb.. I'm lost for fixes.. thanks again for your time.. any help is appreciated.
So, starting from scratch, last year (7/15) i was taking a cruise one evening and (have never had an issue with motor-flawless performance) i hit a choppy part of the river and all of a sudden the motor drops power like its out of fuel(3/4 tank) drops like 800-1000 rpm and starts cycling between running good for a second then dropping rpms like its running out of fuel. I turn around and head back to ramp, take to local reputable certified yamaha dealer and describe issue. They change the fuel pumps and say "its running great"(on muffs albeit).. so i pick up the boat and take it out and its doing the same thing only its dropping(stumbling) 3-500 rpm in a chop for a few seconds then picking up and running ok for 1 or 2 secs. So i carry back and describe the deal and they say its the carbs need rebuilt. So i have them rebuild the carbs and they say its ready, so i pick it up... get out and run it and once i hit the chop(1'-1.5' waves) it starts again.. only its dropping 200 rpm for a sec and then jumping back up and running fine, then dropping 200 etc...stumbling enough to notice the loss of power- and i smell fuel. At this point i shut off the motor, pull the cowling and there's fuel dripping out of the bottom of the airbox/breather so i crank it and the fuel begins pouring out of the breather box... soooo i swing around and head towards the ramp, return the boat and describe everything and show a video clip of what its doing(including the fuel pouring from airbox/breather) starting to get a little frustrated. (each time i take boat back they put it in line and it takes a week to get the boat back).. i also ask them if it could be a coil pack or electrical and they say no, that all the coils checked out ok... they say i needle and seat was bad(after a fresh rebuild???) so they fix the needle and seat issue- i ask them to take the boat out and trial test it politely, which they do and also carry an aux tank. They return and say the problem is a crimped fuel line at the lower cowling inlet grommet(where all the lines enter the motor) well, i had them replace all the fuel line from tank to onboard filter on motor/external micron filter/bulb/fuel tank bulkhead fitting with check ball/pickup tube in tank/screen on pickup tube/...(all brand new stuff complete from tank to motor).. soooo, i didn't ask them to trial run after replacing all that because i figured that would do it... well, a week later i was able to take the boat out and it happens again... 200 rpm drop in chop. at this point i have my wife drive the boat and i start pumping the bulb while its stumbling.. at this point the added pressure (from the bulb being pumped) the engine picks up 300 rpm and runs awesome as long as I'm pumping the bulb.. so once the water slicks off everything runs great again..so i get the idea that I'm losing fuel pressure from lack of ?? vacuum? maybe? i get back to my house and double check everything the mechanic did (i am a decent mechanic but not an "outboard" mechanic) so i know enough to double check all the hose clamps and even put 2nd hose clamps on everything to ensure for secure fits.. go back to the river and same thing... 200 rpm drop. At this point i put my own idea in place, an inline fuel assist pump making 2-3lbs of pressure. wire it in with fuseable link and heat shrink and head to the river.. same thing... i pump the bulb and it picks up the pace and runs fine again..hit the chop and it drops 200 rpm again.. soooooo.. here we are a few months later coming up on a years worth of waiting and tinkering and i figured id run this story by the field of experts and see if this sounds familiar.. any ideas would be appreciated.. i am now considering an inline pump with a regulator and dialing the pressure to whatever a squeezed primer bulb would be (10-13lbs?) and seeing if that corrects it? or checking the float settings? again if it didn't run perfect when i pumped the bulb then id be thinking electrical.. but it straightens out once i pump the bulb.. I'm lost for fixes.. thanks again for your time.. any help is appreciated.