I have a Poulan Pro PP20VA46 lawn tractor that is about a year old. It has a B&S 20hp Intek V-Twin engine. Code is 40N877-0004G1-170627YG. It has run perfectly until a few months ago when someone broke into my shed and stole all my fuel, including draining the tanks of all of my gas-powered equipment (I have a suspect but no proof ). It began surging badly after that. I took apart the carb and gave it a good cleaning. I also did the same for the fuel tank and lines. After that it ran smoothly until a few weeks ago when it began surging again. Once more I took apart the carb and cleaned it but the surging continued. After taking it apart and cleaning it a second time the governor gear exploded (my fault, I misadjusted it). I have since replaced the governor (and I made sure I found all the pieces of the exploded governor) and adjusted it according to the procedure outlined in a service manual another member here was kind enough to send to me. In fact, I have given it what amounts to a full service. Here is what I have done:
replaced fuel, air, and oil filters
cleaned mower deck and frame of debris
sharpened blades
leveled deck and adjusted gauge wheels
adjusted governor and throttle linkage per service manual
changed oil
cleaned fuel system (I use 89 Octane btw)
replaced spark plugs
installed new o rings in carb float bowl
replaced carb manifold gaskets
Cleaned the fuel pump
greased all lubrication points with lithium based marine grease (recommended by another member here)
aired all tired to proper psi
replaced choke return spring
After all this, I am STILL having issues! It starts fine and continues to run but only at full throttle and that roughly. Even then it seems to be operating at a much lower rpm than Fast mode implies. If I throttle down it starts to surge badly. It also surges and loses power when I engage the blades. Even without a load it runs sluggishly just driving it around.
So what could be the issue? I've heard of other people with similar engines having to replace the entire carb. Could this be it? Or could it have something to do with the valves? Or could it be something else entirely? This is my Hail Mary effort before taking it to a professional or taking my sledgehammer to it and buying a new engine. Any input will be greatly appreciated. PS: I did use a liquid gasket maker rather than purchasing a premade gasket for the engine. I'm sure I did a thorough job in sealing the engine case however. Should I crack it open again and replace it with a premade gasket?
Mike I never use a tube of gasket maker if there is a gasket available.......... Where did you use it at.... ???
Your surge issue has to do with fuel. You carb is still dirty inside in some other hard to reach areas...... You more than likely have the Nikki 2 barrel carb on yours and those kits are pricey,,,,,
I would invest in a ultrasonic cleaner and watch a few videos on you tube on your carb... Just cleaning a bowl doesn't cut the mustard on those finicky carbs.......
Harbor freight has those cleaners for cheap......
Let us know Mon Ami ~!~!
Most of this has nothing to do with surging. Getting the carburetor CLEAN has everything to do with it. Spraying with a pressurized can rarely gets the internal passages clean. If you're not going to clean it properly, get a new carburetor.I have a Poulan Pro PP20VA46 lawn tractor that is about a year old. It has a B&S 20hp Intek V-Twin engine. Code is 40N877-0004G1-170627YG. It ran perfectly until a few months ago when someone broke into my shed and stole all my fuel, including draining the tanks of all of my gas-powered equipment (I have a suspect but no proof ). It began surging badly after that. I took apart the carb and gave it a good cleaning. I also did the same for the fuel tank and lines. After that it ran smoothly until a few weeks ago when it began surging again. Once more I took apart the carb and cleaned it but the surging continued. After taking it apart and cleaning it a second time the governor gear exploded (my fault, I misadjusted it). I have since replaced the governor (and I made sure I found all the pieces of the exploded governor) and adjusted it according to the procedure outlined in a service manual another member here was kind enough to send to me. In fact, I have given it what amounts to a full service. Here is what I have done:
replaced fuel, air, and oil filters
cleaned mower deck and frame of debris
sharpened blades
leveled deck and adjusted gauge wheels
adjusted governor and throttle linkage per service manual
changed oil
cleaned fuel system (I use 89 Octane btw)
replaced spark plugs
installed new o rings in carb float bowl
replaced carb manifold gaskets
Cleaned the fuel pump
greased all lubrication points with lithium based marine grease (recommended by another member here)
aired all tires to proper psi
replaced choke return spring
I'm not familiar with your engine, but some engines control crankshaft end play with this gasket.PS: I did use a liquid gasket maker rather than purchasing a premade gasket for the engine. I'm sure I did a thorough job in sealing the engine case however. Should I crack it open again and replace it with a premade gasket?
Most of this has nothing to do with surging. Getting the carburetor CLEAN has everything to do with it. Spraying with a pressurized can rarely gets the internal passages clean. If you're not going to clean it properly, get a new carburetor.
I'm not familiar with your engine, but some engines control crankshaft end play with this gasket.
This is my first time trying to repair anything mechanical, teaching myself and learning as I go in order to be more self-sufficient. Until yesterday I didn't even know what a Welch plug was and everything I listed was to show how thorough I am trying to be for the engine and the overall unit. Later this morning I will be taking the carb apart yet again to clean it as suggested. As far as the gasket it concerned, I haven't found anything to suggest it has anything to do with the crankshaft end play. In will research further. I am still wondering if the valves are part of the problem. Thanks for the input.
Yes Bert has a good Idea.....
Mike you have to destroy the welch plug to get it out.... Do not use anything to seal it... To install it just use a 1/4 inch punch or something equal to that size and indent the center of the new plug..... It should be flat when installed right....
Mike, in case you do decide to replace your carb, you may want to try a CHEAP chinese job, I replaced a carb on a 10 HP Tecumseh eng. and a carb on my 17.7 HP Briggs, both bought from the ROP Shop on ebay.. to my surprise they both work great, had to adjust idle speed ( only screw on these carbs ) but as cheap as they were .. (less than $20.00 ea.) I figured what the hell, saved myself a few hundred bucks against the OEM carbs. ..... just sayin ...........
Thanks for the info! Will look into that. Like you said: what the Hell, eh? At this point I'm ready to try the local witch doctor
EASY does it, PATIENCE & PERSISTANCE will over-come .........
Mike out of curiosity I checked the ROP shop AND ALL of ebay, no replacement carb !! DUH !! BUT.. there is a used carb & manifold for $55.00 + shipping (about $16.00) = $70+ bucks if that interests you, BUT it ends Monday , might try to contact seller ASAP .. if you're interested.. your engine may be too new on the market for them to mfg those carbs. NEW carb = $ 165.00 and UP ..OUCH !!
SORRY if i dashed your hopes of a CHEAP carb.. MY BAD !!
here's some info ..
https://www.ebay.com/itm/Briggs-Str...675948?hash=item4d78a6c06c:g:fJ0AAOSw7pZbXSZz
https://www.jackssmallengines.com/j...-40n899/40n877-0004-g1/carburetor-fuel-filter
https://www.repairclinic.com/Shop-F...Briggs-Stratton-Small-Engine-Carburetor-Parts
https://www.partswarehouse.com/40N877-0004-G1-Briggs-and-Stratton-Engine-s/239559.htm#
Your carb is SIMILAR to the NIKKI 1 Bbl. used on the SINGLE cyl. Briggs engines (28-30 Series) check out this rebuild procedure it might prove helpful to ya ... Boo
http://outdoorpowerinfo.com/repairs/briggs_intek_single_ohv_nikki_carb.asp
Thank for all your input! I will check into it.
Anybody living close to a Marina on the water should have no problem getting NON Ethanol gas, MOST marinas have it .
I have been intensely studying the carb (BS# 699807) in the links you sent earlier. Although it is not listed as being used/compatible on my particular engine (40N877-0004G1-170627YG) it appears to be virtually identical to my present carb (BS# 594207). The only difference I can easily see is that the rocker tab on the end of the choke shaft is slightly different. However, the placement for the linkage seems the same. Everything else looks to be a match. I am beginning to wonder if manufacturers sometimes make a very minor change to a part and assign it a brand new code so they can say it is a different part and charge an arm and a leg for it. I am definitely going to keep 699807 in mind, even if the one in the links is a knockoff. Thanks again!
Usually it's just a change in the main jet size or the linkage, you could possibly swap the choke rod assy. from your old carb to the replacement if really necessary. I checked the parts lists and the carbs use most of the same P/Ns ... my engine is th 404500 series if you care to check,
https://www.ereplacementparts.com/b...engine-parts-c-16758_17347_240657_240714.html
Got the new Welch plugs yesterday. Soaked the carb in cleaner overnight, ran wire through the holes, sprayed it down with another can of carb cleaner, etc etc etc. Got it all back together this morning and it started and ran smoothly, except...
The engine is still running at a low rpm and does not respond to the throttle control. Fast or slow, makes no difference. All the linkages seem to be moving correctly, all springs are present. Guessing now I need to get a tachometer and check the RPM? Pull the flywheel and check the key? Reset all the linkages? ??????????
OK Mike, it sounds as though you have a linkage issue, are you sure the throttle /choke cable(s) are properly adjusted and moving their full travel ?? here's a few vids to check on your governor spring and throttle setting, check it out, and let us know what's happening ....
https://www.youtube.com/watch?v=U7rvHH0IPPk
https://www.youtube.com/watch?v=BL6WmE7pPKs
Mike, I know it's frustrating, MANY of us have been there, why do you think this site exists ?? it has to be something we've overlooked, something simple .. are you absolutely positive you have the governor adjusted and tightened correctly, ?? have you tried to push on the governor arm with your finger to see if it will increase RPMs ?? I hate to give you more vids but it might spark a thought, from memory of something.. as usual, keep us posted.....
https://www.youtube.com/watch?v=tOoArROpM_o
https://www.youtube.com/watch?v=mi3uEdiRD2A
PATIENCE Mike .. PATIENCE & Persistence !! ..:thumbsup:..:thumbsup:
Congrats Mike !! I'm hopin when you do a final test (under load) .. all is well, I suspected you had the throttle cable in the wrong hole on the throttle bracket, ( am I correct ..?? ) and about running HOT... have you removed the engine shrouds to clean the cooling fins,.. correct oil level,.. the flywheel "vane" linkage hooked up & working correctly ..??? Lets NOT cook an engine at this point !! ..:thumbsup:
Success!!! Today was the first chance to mess with my mower since my last post. I fine tuned the linkage, used my new tachometer to set the idle speed, tightened the belt, and...it worked!!! It starts up on the first turn of the key, idles smoothly, and runs perfectly when the blades are engaged. I'm still thinking it seems to be running hot but I will address that later. At least it is working now!!! Thanks to everyone who offered their opinions, comments, and suggestions. I've learned a lot and now want to fix something else. BTW: to anyone in the hurricane path, stay safe.
Stay in touch Mike ... :thumbsup:
Good morning! I finally had the chance to give my mower a full workout yesterday and spent it mowing my entire several acre property. It worked great, even cutting through the thickest grass with ease. It seems my concerns about it running hot were unfounded. It did get hot, of course, but operated even better once it warmed up. Now to diy a grass catcher...