All-Terrain Lawn Tractor Forum
Would you like to react to this message? Create an account in a few clicks or log in to continue.

All-Terrain Lawn Tractor Forum

Like riding lawn tractors through mud, woods, rocks, and snow? Then this is the place for you! Share your ideas, Post your projects and more!
 
PortalHomeSearchRegisterLog inTop Tractor Challenge

 

 briggs 12.5 Idle Surge HELP!

Go down 
5 posters
AuthorMessage
WilliesBuilds
Screwdriver
Screwdriver
WilliesBuilds


Age : 26
Join date : 2013-06-19
Posts : 329
Forum Rep : 0
Location : Florida

briggs 12.5 Idle Surge HELP! Empty
PostSubject: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitimeTue Jan 14, 2014 9:30 am


any ideas guys . icleaned the carbs and checked the plugs twice. and im still learning about troubleshooting the carbs a bit
Back to top Go down
T-Dub13
Monkey Wrench
Monkey Wrench
T-Dub13


Age : 52
Join date : 2013-12-06
Posts : 540
Forum Rep : 2
Location : Central MA

briggs 12.5 Idle Surge HELP! Empty
PostSubject: Re: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitimeTue Jan 14, 2014 10:07 am

Too lean.  Wink 
Low speed Jet, Pilot jet, whatever you want to call it... If it's a screw adjustment, go CCW until it smoothes out. If it's a brass jet, then use a torch tip cleaner to clean it out.
Could also be an air leak or you forgot to put in the air filter.
Good luck, keep us posted.
Back to top Go down
WilliesBuilds
Screwdriver
Screwdriver
WilliesBuilds


Age : 26
Join date : 2013-06-19
Posts : 329
Forum Rep : 0
Location : Florida

briggs 12.5 Idle Surge HELP! Empty
PostSubject: Re: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitimeTue Jan 14, 2014 1:15 pm

that didnt help . im starting to think its the governer. because when i hold the butterfly with my finger it runs smoothly . but when i dont it starts surging and going back and forth  briggs 12.5 Idle Surge HELP! 2429134702 
Back to top Go down
T-Dub13
Monkey Wrench
Monkey Wrench
T-Dub13


Age : 52
Join date : 2013-12-06
Posts : 540
Forum Rep : 2
Location : Central MA

briggs 12.5 Idle Surge HELP! Empty
PostSubject: Re: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitimeTue Jan 14, 2014 1:51 pm

Still too lean.

When it surges like that, it's because it's not getting enough fuel from the low speed circuit, RPM's drop and the governor opens the throttle to compensate.
BUT nothing happens in that split second, so the governot opens the throttle even more. Enough so that it pulls from the high speed circuit.
By the time the motor gets enough fuel to start recovering, the throttle is way more open than it should be and the RPM's overshoot the target RPM. Then the governor closes the throttle and it happens all over again.

It's commonly referred to as "searching for fuel" where I'm from.

Does your carb have a low speed adjustment or a fixed jet?
Back to top Go down
WilliesBuilds
Screwdriver
Screwdriver
WilliesBuilds


Age : 26
Join date : 2013-06-19
Posts : 329
Forum Rep : 0
Location : Florida

briggs 12.5 Idle Surge HELP! Empty
PostSubject: Re: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitimeTue Jan 14, 2014 2:29 pm

Yeah it make sense the searching for fuel term . but heres a pic of the carb ive been fiddeling with that main screw tho only that one dont know of another one to move

briggs 12.5 Idle Surge HELP! P1140710
Back to top Go down
T-Dub13
Monkey Wrench
Monkey Wrench
T-Dub13


Age : 52
Join date : 2013-12-06
Posts : 540
Forum Rep : 2
Location : Central MA

briggs 12.5 Idle Surge HELP! Empty
PostSubject: Re: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitimeTue Jan 14, 2014 2:38 pm

Sorry Buddy, I forget what the idle circuit looks like so I can't help you other than saying that the screw in your pic should regulate the idle mixture to a certain point. It won't help if you've got a blockage elsewhere though...

The other screw obviously will raise the idle speed. Take 'er apart again and find the path for the low speed circuit and clean it again. Find the brass jet and clean it to the point of removing a tiny bit of brass. These carbs run lean from the factory usually anyway.
Back to top Go down
WilliesBuilds
Screwdriver
Screwdriver
WilliesBuilds


Age : 26
Join date : 2013-06-19
Posts : 329
Forum Rep : 0
Location : Florida

briggs 12.5 Idle Surge HELP! Empty
PostSubject: Re: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitimeTue Jan 14, 2014 8:32 pm

I backed off that brass screw at the back just a lil bit and it seemed to fix it . Is this good or bad ? Have mo idea what this screw is
Back to top Go down
Dipshaw87
Screwdriver
Screwdriver
Dipshaw87


Age : 26
Join date : 2014-01-02
Posts : 135
Forum Rep : 0
Location : Vanderbilt, Pa

briggs 12.5 Idle Surge HELP! Empty
PostSubject: Re: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitimeTue Jan 14, 2014 9:13 pm

If you backed off the screw you richened the air fuel mixture (if I'm correct) and yea that's good
Back to top Go down
WilliesBuilds
Screwdriver
Screwdriver
WilliesBuilds


Age : 26
Join date : 2013-06-19
Posts : 329
Forum Rep : 0
Location : Florida

briggs 12.5 Idle Surge HELP! Empty
PostSubject: Re: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitimeTue Jan 14, 2014 9:25 pm

Now I have 2 questions how can I keep this screw in place and No.2 my mower ran just fine is it normal for this to randomly happen  scratch 
Back to top Go down
Dipshaw87
Screwdriver
Screwdriver
Dipshaw87


Age : 26
Join date : 2014-01-02
Posts : 135
Forum Rep : 0
Location : Vanderbilt, Pa

briggs 12.5 Idle Surge HELP! Empty
PostSubject: Re: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitimeTue Jan 14, 2014 9:33 pm

It should have a spring on it to keep tension on it so it won't vibrate itself out when the motor is running. And it depends on a few factors. Bad gas can do bad things to a carb. It can make it run like crap. Type of fuel would have something to do with it as well. These new gases with the ethanol in it make my briggs run pretty bad and I have to put ethanol treatment in it then it runs great. I have cleaned everything on my carb a few times and tuned it and it still does it. And overtime a carb will need to be re tuned in order to make it run at it's best
Back to top Go down
WilliesBuilds
Screwdriver
Screwdriver
WilliesBuilds


Age : 26
Join date : 2013-06-19
Posts : 329
Forum Rep : 0
Location : Florida

briggs 12.5 Idle Surge HELP! Empty
PostSubject: Re: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitimeWed Jan 15, 2014 8:05 am

so this morning i put a pin sized drop of thread lock and now it stays in place and it runs great
Back to top Go down
willis923
Hammer
Hammer
willis923

1000 Posts
1K Posts!

Age : 25
Join date : 2013-04-10
Posts : 1408
Forum Rep : 0
Location : Galway NY

briggs 12.5 Idle Surge HELP! Empty
PostSubject: Re: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitimeWed Jan 15, 2014 8:27 am

you should still get a small spring for it. thread lock may have been a bad idea. i'd just go get a spring. hell, one from a ball point pen may work (the clicky kind of pen)

_______________________________________________
-1974 bolens 1055 (Rolling Thunder)
-1989 Craftsman GT6000 (Blockhead)
-2004 Ford F-250 super duty FX4
-1999 Ford F-350 Superduty 4x4 7.3 Powerstroke


Lt wrote:
Feel free to try... Dont let anything but fear and common sense stop you. 


briggs 12.5 Idle Surge HELP! Pbucket

Chat moderator

1st Lieutenant, Volunteer Firefighter, EMT-B, Galway Vol Fire co. Galway NY
Back to top Go down
Dipshaw87
Screwdriver
Screwdriver
Dipshaw87


Age : 26
Join date : 2014-01-02
Posts : 135
Forum Rep : 0
Location : Vanderbilt, Pa

briggs 12.5 Idle Surge HELP! Empty
PostSubject: Re: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitimeWed Jan 15, 2014 8:32 am

Yea thread lock isn't the greatest cause it could go in between the threads of the screw and block the holes for the fuel to pass inside the carb.
Back to top Go down
willis923
Hammer
Hammer
willis923

1000 Posts
1K Posts!

Age : 25
Join date : 2013-04-10
Posts : 1408
Forum Rep : 0
Location : Galway NY

briggs 12.5 Idle Surge HELP! Empty
PostSubject: Re: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitimeWed Jan 15, 2014 8:34 am

@Dipshaw87 wrote:
Yea thread lock isn't the greatest cause it could go in between the threads of the screw and block the holes for the fuel to pass inside the carb.
then, well... were right back where we started... lol

_______________________________________________
-1974 bolens 1055 (Rolling Thunder)
-1989 Craftsman GT6000 (Blockhead)
-2004 Ford F-250 super duty FX4
-1999 Ford F-350 Superduty 4x4 7.3 Powerstroke


Lt wrote:
Feel free to try... Dont let anything but fear and common sense stop you. 


briggs 12.5 Idle Surge HELP! Pbucket

Chat moderator

1st Lieutenant, Volunteer Firefighter, EMT-B, Galway Vol Fire co. Galway NY
Back to top Go down
WilliesBuilds
Screwdriver
Screwdriver
WilliesBuilds


Age : 26
Join date : 2013-06-19
Posts : 329
Forum Rep : 0
Location : Florida

briggs 12.5 Idle Surge HELP! Empty
PostSubject: Re: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitimeWed Jan 15, 2014 8:39 am

yeah ill go check it at lunch. but i put it right at the top of the screw threads very little and right at the top because i thought it could clog things too lol
Back to top Go down
T-Dub13
Monkey Wrench
Monkey Wrench
T-Dub13


Age : 52
Join date : 2013-12-06
Posts : 540
Forum Rep : 2
Location : Central MA

briggs 12.5 Idle Surge HELP! Empty
PostSubject: Re: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitimeWed Jan 15, 2014 10:16 am

I wouldn't worry too much about the threadlocker. If you applied it to the outside of the screw with it assembled, I don't think it will wick in far enough to clog anything.

Willis is right about the spring though. It's the correct way to retain the screw.
Back to top Go down
WilliesBuilds
Screwdriver
Screwdriver
WilliesBuilds


Age : 26
Join date : 2013-06-19
Posts : 329
Forum Rep : 0
Location : Florida

briggs 12.5 Idle Surge HELP! Empty
PostSubject: Re: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitimeWed Jan 15, 2014 11:03 am

i got a spring from a pen and i will try that lol
Back to top Go down
1997 Murray
Hammer
Hammer
1997 Murray

1000 Posts
1K Posts!

Age : 23
Join date : 2013-11-13
Posts : 1311
Forum Rep : 2
Location : NW USA

briggs 12.5 Idle Surge HELP! Empty
PostSubject: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitimeWed Jan 15, 2014 11:13 am

don't it already have one?
Back to top Go down
T-Dub13
Monkey Wrench
Monkey Wrench
T-Dub13


Age : 52
Join date : 2013-12-06
Posts : 540
Forum Rep : 2
Location : Central MA

briggs 12.5 Idle Surge HELP! Empty
PostSubject: Re: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitimeWed Jan 15, 2014 11:26 am

@1997 Murray wrote:
don't it already have one?

lol, you're right! Looks like there is already a spring on there. If he loosened a different screw, that's not good.  lol! 
Back to top Go down
WilliesBuilds
Screwdriver
Screwdriver
WilliesBuilds


Age : 26
Join date : 2013-06-19
Posts : 329
Forum Rep : 0
Location : Florida

briggs 12.5 Idle Surge HELP! Empty
PostSubject: Re: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitimeWed Jan 15, 2014 12:10 pm

yeah its the second screw behind the main one
Back to top Go down
WilliesBuilds
Screwdriver
Screwdriver
WilliesBuilds


Age : 26
Join date : 2013-06-19
Posts : 329
Forum Rep : 0
Location : Florida

briggs 12.5 Idle Surge HELP! Empty
PostSubject: Re: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitimeWed Jan 15, 2014 12:10 pm

is it the pilot jet?
Back to top Go down
T-Dub13
Monkey Wrench
Monkey Wrench
T-Dub13


Age : 52
Join date : 2013-12-06
Posts : 540
Forum Rep : 2
Location : Central MA

briggs 12.5 Idle Surge HELP! Empty
PostSubject: Re: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitimeWed Jan 15, 2014 1:34 pm

In your picture, the top screw shown is the idle speed. The second one down, at an angle is the pilot adjust screw. The smaller one just below and to the right is the pilot jet (I think). Have you taken out the jet to clean it?
Back to top Go down
WilliesBuilds
Screwdriver
Screwdriver
WilliesBuilds


Age : 26
Join date : 2013-06-19
Posts : 329
Forum Rep : 0
Location : Florida

briggs 12.5 Idle Surge HELP! Empty
PostSubject: Re: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitimeWed Jan 15, 2014 1:54 pm

yup its super clean
Back to top Go down
Sponsored content





briggs 12.5 Idle Surge HELP! Empty
PostSubject: Re: briggs 12.5 Idle Surge HELP!   briggs 12.5 Idle Surge HELP! Icon_minitime

Back to top Go down
 
briggs 12.5 Idle Surge HELP!
Back to top 
Page 1 of 1

Permissions in this forum:You cannot reply to topics in this forum
All-Terrain Lawn Tractor Forum :: Technical Forum :: Engine Tech :: Briggs and Stratton-
Jump to: