18hp Briggs will not go FULL THROTTLE

[Kentguy13]

Hey all! I've been on here a while... and even have the cart this motor is on listed in a few different spots. I finally pulled this cart out of the shed last month and it seemed to run as good as the day I put it away. After a few tanks of gas, and several yard doughnuts later, the engine will not rev up past half throttle. I have tried:

- fresh gas
- removing the air filter
- adjusting the carb screw
- adjusting the idle

Not any significant changes with any of them. It will rev all the way with the choke in the starting position, but even then its spotty at best. The motor sounds good, and is not blowing smoke, and when I do manage to get it fully rev'd it sounds healthy. Any suggestions to getting my engine back to normal?

It is in the 90's today... probably the hottest I've ever tried driving this.

This is the thread build... 18hp rigid frame

 

[anderkart]

The Main jet in your carb might just be partially plugged up, probably wouldnt hurt to clean the whole carb. But first you could check to make sure your carbs mounting bolts aren't just loose, and that your getting a good flow of fuel from the tank.

 

[Kentguy13]

Thanks, I was thinking about this problem last night and that's kinda where my thoughts went. I do not have a fuel filter on this thing (YET, but I will by tomorrow lol), so it is a very likely culprit. I added some injector cleaner to the gas and am running it thru now. I'll report back with my findings.

 

[Bluethunder3320]

try taking the belt off and manually revving the carb butterfly

 

[Kentguy13]

Well I have not made it up to the parts store yet for a fuel filter and carb cleaner spray. I have run about half a tank of gas with injector cleaner and no positive changes.

I did try taking the belt off and running the motor up, doesn't make a difference. I'm going to try the carb cleaner tomorrow, and if that doesn't help I'll pull the intake manifolds and carb off for a good cleaning. I just really did not want to do that! grr.

 

[Bluethunder3320]

not sure if this is what you did, but i mean to rev the engine directly on the carbeurator, not by the linkage. the governor could be out of adjustment or have a worn spring causing it to not pull back all the way.

 

[Kentguy13]

not sure if this is what you did, but i mean to rev the engine directly on the carbeurator, not by the linkage. the governor could be out of adjustment or have a worn spring causing it to not pull back all the way.

Your right... I did not do that. I wish I would have read this post an hour ago. I just took the top half of the carb apart and sprayed it down and cleaned it out real good. In the process the gasket fell apart, so up to the mower shop in the morning for a new gasket to put it back together. If it still does the same thing after cleaning her all up, I'll do what you said. Thanks for the input.

ryan

 

[Kentguy13]

Well I made it down to the mower shop and bought the $2 gasket, put the carb back together, hooked up the fuel filter... and started her up. It acted a little funny for the first minute, but then it sounded as if what ever was causing the problem broke loose and she is almost as good as new.

I do however.... think Bluethunder is on to something when mentioning the governor. I don't think that was the problem... but it is slightly out of adjustment, so when I get some more time I will mess around with that as well. Thank you everyone for the input and advice. I do love this forum.

 

[Bluethunder3320]

glad to hear its working, you should get a fuel filter