The Surge

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  #1  
Old 06-27-07, 08:43 PM
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Exclamation The Surge

I just picked up a Huskee Lawn tractor from a co worker and am currently working on getting it running correctly. Right now, to keep it running ( it fires up after a few cranks ) I have to keep the choke closed or partially closed, no matter how long the things been running. I can drive it around the yard in all 4 gears with no problem. However, I'm still missing the air cleaner for it and will be getting it before I start putting serious hours on the engine.

It's got an 18hp Briggs and Stratton twin cylinder. Model 422707 type 138 01 code 8503012.

I literally get fuel spraying up through the carb when the engine is under load ( going up a hill ) or if the throttle/choke are misadjusted. Today it started sounding like it was running really smoothly, but then I got a surge that I couldn't control via the throttle, only the choke. The throttle seems to act in the way that the cable moves the lever to allow the throttle to open up, but the throttle will close as needed by the engine. It's been years since I've messed with a small gas engine, which is why I'm here. I know this motor isn't working right.

To get it started up when it was first brought home, I had to spray fuel into the carb, it'd run and then die once the fuel was spent. After spraying the carb orifices and the entire carb down with carb cleaner and then giving it a good shot of compressed air, it ran on its own. The fuel diaphram was replaced recently and I cleaned that area out and cleaned the mating surface as some of the old diaphram was still on the carb.

I'm concerned about the fuel spray back up through the carb, the surging and the basic inability to run without choking the motor.
 
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  #2  
Old 06-28-07, 02:42 AM
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It appears you have a carburetor starving for fuel as supported by the fact that if you choke it (limit the air supply) you can get it to smooth out. At a minimum, I'd replace the main jet with a Briggs part number 699173 or if you feel the carburetor could use a complete reconditioning (which I recommend) then pull the carb off, disassemble it, soak it in a bath cleaner (I like Napa's # 6402), spray it off with a spray carb/choke cleaner (I like Briggs # 100042), rebuild it with Briggs kit # 694056 (if it has a 3-screw fuel pump - as opposed to a 4-screw pump) and reassemble and reinstall. If you have a 4-screw pump then the kit will be 693503.
 
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Old 06-28-07, 05:04 AM
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Thumbs up

I was thinking it'd probably need a rebuild of the carb, especially since it had been sitting idle for so long, who knows what kind of varnish has built up in the thing. What's a good source for parts? Am I better off going through B&S online, or finding something local like an ACE hardware that services lawn equipment?
 
  #4  
Old 06-28-07, 10:43 AM
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I recently had an old rider in my shop that had sat for over five years. 10hp Briggs. The owner was an elderly gent with limited income so just for kicks, I tried some SeaFoam in the tank with fresh gas. I still had to use a bit of gas in the intake to get it running, but you could actually hear it smooth out as the SeaFoam did it's work. After running for about an hour, it would start easily with no surge. Give it a try, it's cheaper than a carb kit.
 
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Old 06-28-07, 06:16 PM
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I've heard others speak of the Sea-Foam trick but have never tried it since I run a shop for a profit and don't want to hope something works and have it not work and then spend double the time on a machine at my cost. I'd rather do it once and do it right...recondition the carb! I can't say if an Ace Hardware would have the parts you need, check if they are an authorized Briggs dealer and if not look one up in the Yellow Pages or on Briggs site and do a dealer search in your zip code.
 
  #6  
Old 06-28-07, 07:19 PM
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I've used Seafoam before with mixed results. I guess it just depends on what exactly the problem is. If something gets dislodged instead of disolved, then you are rebuilding the carb anyway. I gotta get the air cleaner on this thing and see how it runs, but what has me wondering is what is going on with the fuel spraying up from the carb with the engine under load like the exhaust from an alcohol powered tractor pull tractor. It seems as if it's dumping too much fuel.

Maybe I have a stuck float?
 
  #7  
Old 06-28-07, 10:05 PM
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No, it's starving for fuel. The fuel you see is normal on acceleration. The intake vacuum pulses are fluctuating badly because of the starvation and the wide open throttle, and causing the droplets of fuel to spray like you see. If it wasn't starving for fuel, the throttle wouldn't be wide open, causing total loss of vacuum, and the fuel would meter into the intake like it should.
 
  #8  
Old 06-29-07, 05:37 AM
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Alright, that makes some sense to me. Looking down the carb it seemed to be dumping fuel, but it was in spurts, so again...makes sense. I'll rebuild it and report back with an update.

I appreciate everyones input! Now if I can just figure out how to put on a sturdy enough hitch on this thing to move my 17ft boat around....
 
  #9  
Old 06-30-07, 02:41 AM
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Whoa, the tranny on these units are not designed for anything more that moving the weight of the mower and the operator and that's it. This is not the right tool for the job of moving around a 3000 lb., net weight, trailer. If you do this too many times you'll be posting here with instruction on how to remove, disassemble and diagnose a transaxle.
 
  #10  
Old 06-30-07, 09:46 PM
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Well, I figured the belt wouldn't handle the stress before the tranny had issues. Chances are slim that I'll get far enough along with it to try to pull the boat around anyway...it was more of a pipe dream. It yanks my 14ft aluminum around just fine tho', and that's what I'm fishing out of anyway. The big boat is my project boat, and I really don't have any problems driving my truck in the yard to move it if need be ( would be nice to be able to move it with something that has a shorter wheelbase though...but I don't have the $$ for a decent ATV.
 
  #11  
Old 06-30-07, 10:15 PM
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BTW, Does anyone know where I'd find a manual for a 1985 Huskee lawn tractor?
 
  #12  
Old 07-02-07, 02:38 AM
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With your model and serial numbers, the MTD website is your first option for any manuals.
 
  #13  
Old 07-26-07, 05:04 PM
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Question finding parts

According to the parts manual, and what the hardware store found based on my engine model number, I have a different carb on this thing because the rebuild kit didn't have any parts that fit with my carb design. I can't seem to figure out how to find the right parts on the B&S site.

The carb had been replaced with a new one apparently at some point according to the previous owner.

The numbers on the side of the carb are as follows

692812
27-531
1807

they are etched on the throttle cable side of the carb. This carb has no adjustments other than an idle screw and it has what seems to be a metering rod/orifice tube accessed only by pulling the top of the carb off.

I'm stumped...any help?
 
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Old 07-27-07, 03:52 AM
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Although the 692812, number, appears to be a Briggs part number, it does not show as a valid Briggs part number according to my lookup software. Perhaps an email directly to the Briggs factory can shed some light on your trouble with the carb identity, if this is indeed a non-original carburetor. Otherwise, bring the carb (and your engine ID numbers) in to an established, authorized Briggs service shop for their opinion and perhaps they will recognize the carb for what it is.
 
  #15  
Old 07-30-07, 05:38 PM
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Yup, something is not correct, that is for sure. Of course, this is a 20 year old motor, perhaps they may have to check parts in the book instead of with the software.

I pulled the carb and since I wasn't going to get a chance to get to my local B&S dealer soon, I dismantled it and soaked it with carb cleaner. The inside of the fuel bowl had a rusty orange colored splotchyness to it that I can only assume was old fuel turned to varnish, and I looked inside the passageways and it looked like there was some crud in them too, so I sprayed carb cleaner in the fuel bowl until it filled up and let it sit for a couple of days hoping it would dissolve the crud and then I'd have some luck after blowing it out with some compressed air... Still have the same old surge. It seems that the motor really never gets up to it's 3800rpm operating range at full throttle either...

I guess I'm just going to have to find that rebuild kit and get a good can of carb dip...

It's strange, the carb utilizes a brass tube with 4 holes on the sides that is screwed into the carb base when the top is removed, and the only other "metering" device is a brass screw with a taper and hole that is accessed through the side of the fuel bowl after removing a large bolt style plug ( I can only assume it meters the maximum fuel flow from the fuel bowl to prevent ever richening the mixture? Not having truly adjustable low and high speed circuits makes this carb a real mystery to me as to its operation ( Particularly as to why I'm it surges the engine with no choke )...meaning, I can't seem to point to the cause of the fuel restriction.

Where should I be concentrating on when I actually rebuild the carb?!
 
  #16  
Old 07-31-07, 03:17 AM
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By your description, it sounds as though you have a two-piece flo-jet carburetor designed for an old school horizontal shaft engine, not the vertical shaft opposed twin cylinder you have. Do you know how to post links to pictures of your engine and carburetor? Since, it appears, that this is a non-original carburetor, I need to have look at what you have in order to better advise you.
 
  #17  
Old 07-31-07, 08:54 PM
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I can host pictures on my google image account and use "[img]insert image url here[/img]" tags if that is what you use here.

How much would a replacement carb be if I end up having to buy the right one? All I seem to be able to find is just simple parts pricing.
 
  #18  
Old 08-01-07, 11:19 PM
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You can host your pics on another lite like photobucket or whatever your choice, and put up a link to them here. Codes in these forums are turned off, so no pics can be displayed.
 
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Old 08-02-07, 06:52 PM
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Ah, gotcha. Took some tonight, I'll get them hosted and put up a link ASAP.
 
  #20  
Old 08-02-07, 07:27 PM
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http://picasaweb.google.com/Redfury111/20070802

Should be pretty easy to see detail, they are all 6 megapixel pictures. If you need another shot of something else, let me know and I'll take a picture and upload it to the same link.
 
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Old 08-02-07, 07:47 PM
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Looks like the carb that is intended for this type engine. I don't know what the numbers problem is, or what the difference was in the carb kit they looked up for you. Your carb is a common downdraft carb found on pretty much all briggs opposed twin vertical shaft engines.
 
  #22  
Old 08-02-07, 08:29 PM
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Yeah, I figured the carb was common to the engine, but the problem is that the rebuild kit listed in the .pdf isn't the correct one. The one listed does not come with the 2 brass orifices that this carb has ( one through the side of the fuel bowl, the other accessed from the top of the carb with the top plate removed...in the body of the carb ).
 
  #23  
Old 08-04-07, 08:32 PM
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I was just over at my dad's place today and he's got the exact same engine ( though newer and labeled as "industrial" ) and the carb he has on his motor is the same as mine. I'm wondering if the carb that was supposed to be on this "older motor" had the adjustable enrichment screws...I may just have to pull the engine numbers off his motor and see what I come up with for a carb.
 
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Old 08-05-07, 05:06 PM
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Does the engine start kind of hard? Your same symptoms happened to me on one of these engines. After reconditioning the carb, new spark plugs, fuel filter, etc... and a LOT of time, my problem turned out to be a sheared flywheel key. It sheared just slightly to throw off the engine and cause surges without preventing it from running at all. Sounds like it would be nothing for you to check the key compared to everything else you've been doing.
 
  #25  
Old 08-05-07, 06:55 PM
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Well, I'll certainly double check. I'm not really sure if the charging system on this thing is working properly, so it'll give me a good reason to go mucking around under the flywheel anyway.
 
  #26  
Old 12-23-07, 12:02 PM
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*update*

Well, I never got around to fixing the carb or doing much work to the thing. End of year, I took the mower deck off and cleaned it up and fixed a loose bearing. One trip around the yard at full throttle and by the time I made it to the back, I lost a cylinder Idiot! I guess that's what I get for putting it off, now I get to tear the engine down and probably replace a piston or a valve if I'm lucky ( there is no compression ).

How do you get the pulleys underneath loose? Are they keyed and set screwed in place?

On an unrelated/related note my Allis Chalmers 8hp snowblower stopped starting up for me after the gas tank was run empty. I bought a can of carb dip and a rebuild kit ( total cost $45 ) and my snowblower started up on the first pull. A half turn on the high speed circuit richer and it's running like a top again...very cool. So, this summer the mower is getting the mechanical failure fixed and that carb is going through the same treatment.

I'm kinda stoked at the ease and success I had with the snowblower, I think I'll tackle the carb on my outboard next
 
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Old 12-23-07, 01:01 PM
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The pulley is held on by a bolt through the hole in the bottom. Remove it with a 5/8" socket.

I don't think the surging would have caused the engine to blow a cylinder. Was the oil low? Usually the top cylinder is the first to go when it's a lubrication issue.
 
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Old 12-23-07, 08:25 PM
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I think I burnt a valve because it was running lean. There was no noise involved in the shut down of the cylinder. I pulled the plug and turned it over with my thumb on the hole and it didn't push anything past ( nor try to ) my thumb.
 
  #29  
Old 06-19-08, 09:09 PM
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update

Couple of updates...I hate to leave threads like this unfinished.

At the beginning of the season I decided to pull the mower off to the side and do some tinkering to find out how bad that cylinder was. Pulled the head off and what did I find but a small machine screw stuck in the intake valve. I lost the cylinder because this little screw somehow found its way in there, but the head of the screw was too big to enter the cylinder ( whew! ) and it just sat there and got mashed by the valve. No apparent damage to the valve or the valve seat on a visual inspection, I reassembled the motor. A quick shot of gas in the carb and it fired right off, both cylinders strong!

So, the carb issue has been resolved also. I bought a rebuild kit and went through the carb thoroughly. The one thing that had bugged me when I had taken it apart previously was verified. My jet was partially plugged by hardened debris and I didn't have a small enough drill bit to attempt to "repair" it. The new carb kit had a new jet so I could see that where I figured it had a hole indeed had a hole! New carb kit installed, and it runs like a champ, no choke needed. It starts up like a new mower and it ran so good, I ended up damaging my drive belt smashing through snowbanks in my yard before they had all melted. It was quite fun and I'm sure I looked like a big old goofball out there with my jacket on driving my old lawn mower around the yard in the snow.... :mask:

So, all is good. Blades are sharpened, gotta get a new belt and change the oil. She's old, but now old and trustworthy. All I really gotta do now is get one of those nice John Deere style wheels for the leading edge of my mower deck so it stops gouging my yard.
 
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Old 06-19-08, 09:21 PM
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Great! Glad it was a simple fix, and thanks for the update!
 
  #31  
Old 06-20-08, 05:52 PM
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No problem. Hopefully someone else will be inspired to repair their old mower and realize that you can never make assumptions on anything, and that a little patience and effort goes a long way. Wish I would have kept that carb rebuild kit part number though so I could have posted it here for anyone else that may need to purchase one in the future. The old fella at the Hardware Hank/Toro repair shop got me the right kit after searching the microfiche with the carb in hand. I didn't get to dip the carb with my carb dip because I had loaned it out to a friend who is rebuilding 2 carbs on his boat, but considered that I had soaked in in carb cleaner before and blew it out, and sprayed it down again with carb cleaner and blew it out...it was plenty clean. I just made sure I blew carb cleaner through every possible hole in the carb body. It looks like a new carb, and I've been mowing the yard all summer with hardly an issue....other than the steering ( the original steering column hole got rounded out and I had to use a large washer, a collet and some rivets to secure the column so the gear wouldn't skip when I tried to turn the wheel. I'll fix it properly someday when I get around to tearing it down and repainting the whole works.
 
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