Throttle Lever to Screw stalls engine?

SnapperOwner

LawnSite Member
Location
Ohio
B&S Vanguard V-Twin 23hp
Model 386777
Type 0111-E1
Code 0705241
Part 2690752
TK Carburetor
550 hours right now
Purchased February 2009
Snapper YT2350 YT400 Series 50" Lawn Tractor (aka Riding Mower)

Warning: I always sound like I know more than I do! Please don't be afraid to ask the simple questions.

Just took over maintenance on our home mower, after 12 years of neglect and abuse. Been working at this for five solid weeks now, and I feel like it's never going to end. My daughter is mowing two acres of rural-Ohio grass with a weedeater and would like to see this fixed. Very limited budget, and I have to have all my parts ordered and shipped in from a city, so I can't afford to just start replacing everything without thinking it has a problem. I only use OEM parts anymore.

Thanks for being here, because I need all the help I can get.

Checked and/or replaced in the last five weeks (always OEM parts):
* Valve lash was spot on at .005 on all four arms but replaced both valve-cover gaskets and breather-to-valve seal on the breather assembly that sits on top of C2 valve.
* Dipstick filler tube with both o-ring seals replaced (had leak at bottom, which this fixed).
* Fuel pump replaced.
* Carb pulled off and cleaned twice now. Float and needle valve (the one with the rubberish red tip) look fine and passed the "blow test". Replaced the air-filter-to-carb gasket. Probably should have replaced the Intake gasket, but it looked okay. If I have to pull the carb again, I'll replace it. Idle mixture screws no longer have limiter caps.
* Spark plugs and air filter replaced with Briggs as specced (not so before).
* "Dethatched" flywheel fins when the cover was off for the valve adjustments. It was SOLID matter in there.
* Changed oil three times, because it had gas in it when I took over. Doesn't lose or gain oil level overnight or after use.

Choke and throttle cables have been recently reset by someone who didn't know what they were doing, so they may be in the wrong position. Since the manuals only says "replace ***** cable and move on", I can't find instructions for setting them.

I'd like to take the problems one at a time, if I may. My first problem right now is that I can't get the engine set to idle speed of 1200 the way the page says to (see attachment), using a cheap but seemingly reliable non-contact Tach from Amazon. When I push that throttle lever against the bottom of the Idle Speed screw, the engine stalls within 5 seconds. If I don't push the throttle lever up, the engine has a bad surge on low at 1340 (can't get it lower without stalling) and not quite so detectable at 3400 on high.

Problem -- If I can't hold the throttle lever to the screw, I can't get the Idle Mix screws to have any affect whatsoever. Also, I can't get the Low to 1200 or the High to 3600, because to adjust the Idle Speed screw, you're back to the same lever-to-the-screw problem.

Any advice for me? I'm "stalled" in my repairs, until I can get past this.

Briggs Op Manual Carb Adjustments page 15.jpg
 

hal

LawnSite Fanatic
Location
Kansas
Does the engine cut off due to no gas or is there a wire connected to the low idle screw to ground it out, shut it off?
 
OP
SnapperOwner

SnapperOwner

LawnSite Member
Location
Ohio
No wire that I can see or know of. It sounds like it's a no-gas issue. When you're on Low, before you move anything, it's chugging and surging like "The Little Engine That Could". Not good, so it doesn't take much to stall it once you get the lever touching the screw. Here are some photos. If you need more, let me know.
 

Attachments

  • DSC07756.JPG
    DSC07756.JPG
    169.4 KB · Views: 36
  • DSC07757.JPG
    DSC07757.JPG
    177.5 KB · Views: 37

hal

LawnSite Fanatic
Location
Kansas
Can you back the low idle mixture screw all the way out and spray some carb cleaner in there? Or does the limiter stop that?
 
OP
SnapperOwner

SnapperOwner

LawnSite Member
Location
Ohio
Limiter caps are gone. Carb's been cleaned 3X in the last five weeks, but it doesn't mean that the person knew what they were doing. I took one of those mixture screws out this weekend, and it appeared to be clean as a whistle. Buuuuut, I know that doesn't necessarily mean it's clean inside. Should I take both screws out (I can reset to the 1-1/2 CCW preset) and spray carb cleaner in there? Do I need to take the carb off the engine to do that, or will it be okay still installed? After I do that and reset the screws, do I just try starting it again without doing any other adjustments and see what happens? Or am I looking for something in particular? (Sorry, I warned you that I'm pretty low on the learning curve.)
 

hal

LawnSite Fanatic
Location
Kansas
Yes take them out one at a time and spray in there. Reset the screws, try and start it, adjust to get it to run. Usually after I spray in the screw hole I screw it all the way in, not too tight and back it out to the reset position, the jet may have some crud in it still. Check and make sure the governor is adjusted correctly too.
 
OP
SnapperOwner

SnapperOwner

LawnSite Member
Location
Ohio
Okay, can do that with the screws. Now, how do I know if the governor needs adjusting? Could the throttle cable be too loose or too tight?
 

hal

LawnSite Fanatic
Location
Kansas
You will need a more knowledgeable person for those details....
 

JoeRagMan

LawnSite Senior Member
Location
Near TMI
Have you checked to see how much a replacement carburetor would cost? I have cleaned many carburetors, one on a Stihl trimmer just would not cooperate after I sprayed carburetor cleaner in all passageways. Lost my patience, pulled it apart a third time and blew passageways out with 100 psi of compressed air, saw a slug of crud go flying, problem solved. If a new carburetor is not an option, is there a local small engine repair shop close by that could help? Barter if you have to, he helps you, you return the favor?
Do you have the manual? Have you searched the web for repair videos? There are many guys and gals that have helped me how things work.
Before you started this project, did you completely drain the fuel tank/lines? Even remove the fuel tank, pour an ounce or two of clean fuel and shake then flip over and pour out to see how it looks?
I had read somewhere that 90% of small engine problems are fuel related.
Good luck.
 
OP
SnapperOwner

SnapperOwner

LawnSite Member
Location
Ohio
Replacement carb was $270 a month ago, but it would have to be modified. Apparently, Briggs no longer makes a model to direct-fit this 12-year-old engine. New is not an option at this point. Besides, I still think the carb must be worth repairing, with only 550 hours on it (over a 12-year period). I'll try the clean again, this time with the compressor running (thanks for the advice), but I'd like to have some other ideas about the stalling when throttle lever and screw are touching.

Unfortunately, there's no small-engine repair shop around here that I'd trust to do troubleshooting. Plenty of parts changers, but not a lot of diagnosing. (And at $75/hour, I couldn't afford it anyway.) This thing has been "serviced" every spring (to the tune of $400-800 per year). Obviously, little was done most of the time. This past June, the earliest I could get an appointment with a mechanic within a 35-mile radius was February 2021 ($90/hour). The mechanic we usually use isn't writing new tickets anymore, he's so backed up. The other two in our area were put out of business by Covid restrictions. And I've never met a mechanic who would barter for anything except cash.

Have all three manuals (Service, Parts & Operator) for the engine and have invested an estimated 300+ hours in reading and watching videos online over the last five weeks. This Vanguard model is "unique" (Briggs' own words) and has "special requirements". I'm willing to learn and do the work myself. A little advice would help me along, though. So, I'll keep reading and watching. And thanks for the advice.

By the way, will a small compressor give me the 100 psi (I know someone who has one), or do I need to use a can of air?
 

Top Forums



Top