4.75 hp B&S lawnmower revs then sputters

Reply

  #1  
Old 11-12-05, 08:21 AM
juchmu
Visiting Guest
Posts: n/a
4.75 hp B&S lawnmower revs then sputters

My 4.75 hp B&S lawmower engine would run normally for about 5 minutes, then sputter and then quit. I replaced the carburetor diaphragm (which appeared damaged) and that solved the problem for about 2 weeks. The problem I'm having now is that the engine runs normally for about 5 seconds after starting and the goes through fast cycles of revving up for a few seconds and then sputtering for a few seconds and then revving again and sputtering again and on and on. I took off the air filter and noticed that the smaller one of the two springs between the governer and the carburetor had broken off. Thinking I had a quick fix, I replaced it with an identical spring exactly according to the specifications. But, this failed to solve the problem. Watching the carburetor as the engine revs and sputters I can see the intake valve opening and closing and the governor flapping back and forth. How can I make the engine run smoothly?
 
Sponsored Links
  #2  
Old 11-12-05, 08:57 AM
puey61's Avatar
Member
Join Date: Apr 2004
Location: Upstate New York
Posts: 3,224
You need to clean the carburetor not merely replace the diaphragm. Pay special attention to the pick-up tube, it likely has debris covering the screen or jet.
 
  #3  
Old 11-12-05, 09:55 AM
juchmu
Visiting Guest
Posts: n/a
When I replaced the diaphragm I gave the entire carburetor and gas tank a thorough cleaning.
 
  #4  
Old 11-12-05, 09:29 PM
v8driver's Avatar
Member
Join Date: Sep 2005
Posts: 767
did you soak the carb? you made absolutely sure to clean the tube? the governor on it, should be a windvane governor, that is if you see a plastic flap connected to the carb. they pretty much for newer ones, use two springs( make sure they are not stretched out) one link, and a windvane. make sure the butterfly isn't sticking, and the windvane isn't as well. you didn't fold the new diaphragm?
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes