Makita 4 cycle blower bogs down at max rpm

[katit]

Have this backpack blower for about 3 years. It was running good, now it started to do this.

Everything works as normal, I can do small jobs with low-mid rpms. But when I set it to max RPM it will start bogging down in couple seconds. If I let off gas and accelerate again it will accelerate and then rpms will dip in couple seconds.

What should I look for?

Model: BBX7600N

 

[Kodie's Lawn Service]

common problem on 2 cycles is the screen in the muffler if there is one in the blower take it out an let us know

Thanks Kodie

 

[reynoldston]

Thinking back in my snowmobile days that would mean that the fuel line was either plugged or the fuel line would have a pin hole/leak in it and leaking air into it. It just wouldn't get full fuel flow for higher RPM,s. Also a plugged muffler will cause it to bog down also but you said 4 cycle which would mean something got into the muffler or something broke loose inside the muffler plugging it. I know from running 2 cycle mopeds that carbon build up would plug the mufflers and have to heat them to burn the carbon out and I think that what the earlier post was talking about.

 

[katit]

Do you suggest taking muffler off completely?

I checked screen - pulled it off and it's nice and clean.
I noticed that intake manifold came loose and thought "a-ha!". Tightened, started again, it was working good for about 5 minutes and then started again. It would run almost full RPM and then vary, it may stay running for a while, it may almost stall when I accelerate and hold. But it doesn't run smoothly on top

 

[Mad Mackie]

Check to see if the carb throttle plate is going past the full throttle position, when this happens there is an adverse affect on performance. Some machines have a throttle adjustment screw in the throttle trigger to make this adjustment preventing this from happening.

 

[katit]

I took carb apart, cleaned it. Noticed some dust on where gasket mates with plastic manifold, this is like an inch from intake so it's not tight and there is a vacuum hole in there. Made new gasket, put just tiny bit of silicone around that spot on a gasket.

Seems to be working good now!

 

[lawn mower fanatic]

I took carb apart, cleaned it. Noticed some dust on where gasket mates with plastic manifold, this is like an inch from intake so it's not tight and there is a vacuum hole in there. Made new gasket, put just tiny bit of silicone around that spot on a gasket.

Seems to be working good now!

Glad you figured it out. :thumbsup: