2001 50 up Yamaha bogging in throttle

[Jbeauchamp]

My 2001 Yamaha 50 hp sometimes bogs on throttle. It's real random and occasionally when you are running at full throttle it will start slowing until you are at full throttle but only running at idle speeds. I can usually give full throttle (which will cause motor to die), restart motor and give full throttle again repeating about 3 - 4 times and the boat will take off fine. It usually idles fine but lately seems like a hard miss. I have rebuilt all three carbs, changed plugs, changed fuel line, fuel tank, battery and nothing has helped. I'm starting to think maybe coil buy am unsure. I took it to a mechanic which runs fine and throttles up great on the muffs but once in the water and under load it start acting up.

Any ideas? All posts would be appreciated!

[Jbeauchamp]

My 2001 Yamaha 50 hp sometimes bogs on throttle. It's real random and occasionally when you are running at full throttle it will start slowing until you are at full throttle but only running at idle speeds. I can usually give full throttle (which will cause motor to die), restart motor and give full throttle again repeating about 3 - 4 times and the boat will take off fine. It usually idles fine but lately seems like a hard miss. I have rebuilt all three carbs, changed plugs, changed fuel line, fuel tank, battery and nothing has helped. I'm starting to think maybe coil buy am unsure. I took it to a mechanic which runs fine and throttles up great on the muffs but once in the water and under load it start acting up.

Any ideas? All posts would be appreciated!

Also to mention, I unplugged fuel line going to the three carbs and turned the motor over to check the fuel pump which is pumping great.

[Ldavidgrover]

Did you lynk and synk the carbs

[99yam40]

Check compression, spark, timing, and fuel pressure/vacuum. Make sure timing is advancing to spec at WOT
If all of that is good then you are left with carbs still

Good possibility you had stuff break loose from inside lines or pump that plugs up jet/passage.
He is right about link and sync, needs to be done each time carbs are reinstalled

[Jbeauchamp]

Did you lynk and synk the carbs

No, shade tree mechanic here. I just took the carbs off and never changed the linkage at all. Just put them back on like they were. I will check that this weekend.

Would it cause this to be so random? i ask because it does not do it every time. It may run fine the trip out fishing but later in the day it will start acting up. But then again, it may do it right off the trailer. One thing i did last trip out, i only ran it at 3/4 throttle and it never bogged down while running but towards the end of the week i ran it full throttle and nearly everytime after running at full throttle for about 10 minutes it would start bogging and slow down.

Thanks for the help.

[Jbeauchamp]

Check compression, spark, timing, and fuel pressure/vacuum. Make sure timing is advancing to spec at WOT
If all of that is good then you are left with carbs still

Good possibility you had stuff break loose from inside lines or pump that plugs up jet/passage.
He is right about link and sync, needs to be done each time carbs are reinstalled

Thanks Captain, i will check all that and get back with you. But out of curiosity do you think it could possible be a coil going out?

Thanks for the reply

[99yam40]

No, shade tree mechanic here. I just took the carbs off and never changed the linkage at all. Just put them back on like they were. I will check that this weekend.

Would it cause this to be so random? i ask because it does not do it every time. It may run fine the trip out fishing but later in the day it will start acting up. But then again, it may do it right off the trailer. One thing i did last trip out, i only ran it at 3/4 throttle and it never bogged down while running but towards the end of the week i ran it full throttle and nearly everytime after running at full throttle for about 10 minutes it would start bogging and slow down.

Thanks for the help.

Sounds like you have a restriction in fuel supply and it cannot keep up with fuel needed to run at WOT. plugged vent or restricted pick up tube. Fuel pressure/vacuum test will show this.