Briggs 10.5 surging. About to pull my **** hair out

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155
Location
iowa
Ok have a swisher pull behind mower with a 10.5.bought it without it have being used in a few years. This is gonna be kinda long but I want to go through exactly what I've done.
Engine numbers 215802-0115-e1

Got it to pop off but it yanked the cord out if my hands.
I replaced the recoil starter as it was broken and adjusted the valves. Started right up. But it had some surging.
Since then I've put on new fuel lines, filter, fuel pump, spark plug, air filters, I replaced the head gasket (they're notorious for going bad so I figured why not).
I've cleaned the carb twice and new mixture screw (old one was pretty rough), needle, seat and float, and its been cleaned again.
I could NOT get the nozzle out (walbro carb, no jet) and I actually stripped the head of it so its staying in there but I'm confident its clean, though its possible I'm wrong.
I'm still getting surging. It does not have the solenoid on the bottom, and it doesn't seem to surge under load (when blades are engaged). It does smooth out a little when I go a couple clicks on the choke.

I'm kinda lost here. I didn't, and don't know why I didn't spray some carb cleaner to check for vacuum leaks but ill do that tomorrow (the crank case breather tube is loose a little bit but thats before the carb?) Also im going to ditch the big clear fuel filter for a more free flow disc style.

I've read it could be the governor but I know NOTHING about governors, even in plain English.

I'll post a link to a video below so we're on the same page, my engine is running somewhat (not quite as bad) as the guys mower in the video at the 50 second mark

Lastly if there are any briggs pros.. the parts list has my walbro grayed out and doesn't offer a part number, only offers a Nikki number. If I need a new carb will the nikki be a direct replacement to my walbro? I'm assuming they discontinued the walbro.

Link to video, having a similar problem aa the guy at 50 second mark
 

sh40674

Thread starter
Messages
155
Location
iowa
Cheap Ebay/Amazon carb is where I would head to next.

Surging like you describe can be caused by a bad idle circuit, but that usually brings with it poor or no idle.
This is where I have the question of the nikki/walbro... lots of decently reviewed aftermarket on the nikki part number
 
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1,730
Location
Athens, GA

sh40674

Thread starter
Messages
155
Location
iowa

Says it fits the 215802. My experience with cheap carbs....they usually work and for $15 its well worth it especially since you've thrown way more than that at it already.
That is the number for the nikki carb, like I said just looking for confirmation the nikki is a direct replacement to the walbro.

And no I haven't, how do you check timing?
 
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2,945
Location
Georgia/Retired
Surging is usually caused by a plugged or partially obstructed pilot circuit. Remove the idle mixture screw from the side of the carburetor and flush the circuit with carburetor cleaner. If this doesn't resolve the issue then remove the carburetor and trace the circuit from the bowl to the venturi and ensure there is no obstruction.

I have found that nearly all surge issues are caused by a dirty pilot circuit. Be sure to note how many turns the idle mixture screw is set to before you disassemble it.
 
Messages
6,494
Location
Connecticut
Based on what you have already done (head gasket, valve adjustment, cleaning carb, etc) my thoughts are it could be 1 of 2 things:

1. The gasket between the intake and the head is not sealing all the way causing it to run lean and surge

and/or:

2. The carb idle circuit is still partially blocked

These engines are set to run very lean for emissions reasons, so any tiny bit of build up inside the carb passages will cause the surging. I've had carbs still cause surging even after being in an ultrasonic cleaner a few times, so replacement was the only solution.
 
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3,338
Location
USA
Engine running, blades not engaged, push and hold the throttle lever on the top of the carburetor against the screw stop. This overrides the governor to make it run slower than normal. It should run slow and steady. If it just dies hold it not quite to the stop and if that works, turn the screw out some. If it really doesn't want to run slow, see the multiple posts above about clogged idle circuit. If you can't get the carb apart for a complete cleaning, replace. Air leaks are theoretically possible but really uncommon.

Also some of them just surge with no load, no matter what. The only thing it really needs to do with the blades disengaged is somehow stay running.
 
Messages
658
Location
Kevil,Ky
Even though you can see through the jets just fine, There is a residue from old fuel that makes them smaller. Get yourself a tool that welders use for gas welding. It has many size fine wires that you can push through the jet. You will be surprised at what you see.
 
Messages
222
Try about 2 to 3 ozs. of Seafoam per quart of fuel and just run it. That has worked for me a few times.
My dad had suggested this when my gcv160 was surging last summer. Worked like a charm and that's been the only issue with that engine in 7 years.
 
Messages
2,370
Location
Texas
Surging is usually caused by a plugged or partially obstructed pilot circuit. Remove the idle mixture screw from the side of the carburetor and flush the circuit with carburetor cleaner. If this doesn't resolve the issue then remove the carburetor and trace the circuit from the bowl to the venturi and ensure there is no obstruction.

I have found that nearly all surge issues are caused by a dirty pilot circuit. Be sure to note how many turns the idle mixture screw is set to before you disassemble it.
+1
 

sh40674

Thread starter
Messages
155
Location
iowa
So weird thing... went to start it today and it yanked the cord back. Checked the valves and the intake was off at .009... it was set at .003-.004. Now this could be coincidental since I just adjusted them and maybe it went out some. Adjusted it but it seems the compression release(when the intake valve bumps off during the compression stroke) bumped off fairly early in the compression stroke. Maybe it's just me? Could it be a timing issue?

Anyways got it started and sprayed carb cleaner from the head where the intake tube is to the carb. Sometimes it seems like it helped a little others not. Kinda confusing. So I can't say I definitely have an intake leak.
I did replace the fuel filter with a disc style and I noticed when it ran on the high side it ran a little better, but didn't solve the problem (maybe making up for a lean issue but still surging/waffling)
I also tried above with over riding the governor with no success.

So as if now I'm calling it a carb or timing issue.

So ill start with the carb and get an Amazon job to see if there is a difference. That brings me back to the walbro/nikki question.

And thanks so much fellas for the help so far. Really appreciated
 

sh40674

Thread starter
Messages
155
Location
iowa

I cant say I did all of this, however as stated the nozzle is stripped so I cannot service that. Thats why I'm looking at if the nikki is a direct replacement to my walbro as the off brands are much more readily available and better reviewed. There are too many variables on the off brand wlabro carbs I might not get an exact replacement and I cannot find a part number as I believe briggs scrubbed it. However I will be bookmarking that page!
 
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