Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

Sign in to follow this  
andrewk

Odd briggs problem- need advice

Recommended Posts

andrewk
Hi all- I have been working on a woods mower, which looks like it was made by grasshopper. It has a 422447 briggs twin in it- with the downdraft style flo-jet and the 3-screw fuel pump. It came in for a few different issues- intermittent spark, no charging, and it had water in the fuel due to a bad fuel cap. I pulled the engine, replaced the stator (unregulated charging system with a shorted stator) and the coil, drained and flushed the tank, replaced the gas cap, and put a kit in the carb. Engine was running pretty good. I sent it out the door, and it came back at me a week later. It was running excessively rich, and would die if you turned quickly with it (remember, it is a well balanced zero-turn) I took the carb back apart, and found that I had somehow pinched the fuel pump diaphragm. (I still think he took it apart at home, as I was very careful with this going together.) Anyway, rebuilt the pump again, pressure tested the carb, and put it back together, and got the same result. Dies when you turn quickly (not beating on it, but what a homeowner would realistically do) and runs rich. Carb is a fixed jet, has standard jet in it. Fuel solenoid tests good. I replaced all fuel lines, and the impulse line. Carb is clean, I cleaned it 3 times now. Float is level as per service manual. I have tested for intake leaks, engine has good compression, passes a leak down test. Has good vacuum. The only thing I can think of is that it is generating excessive fuel pressure, but I don't have a pressure tester to test it. My repair manual says that excessive fuel pressure can lead to gas in oil and excessively rich running, both of which I have had, the latter still happening. However, the manual doesn't say that the diaphragm pump can generate too much pressure. I know this is not a simplicity, but I am running out of ideas- Any ideas? The help is much appriciated- I am getting tired of working on this thing! Andy

Share this post


Link to post
Share on other sites
D-17_Dave
The pump can push a lot of pressure if everything is just right. But I doubtt it's the problem. Sounds to me like the bowl is low on gas described when you turn sharp and it starves. The engine will use varying amounts of fuel from idle to loaded wide open. With this in mind is the fuel level in the bowl getting to low when under load? Maybe a restricted fuel flow from the tank. It's also possible that you have a blown intake manifold gasket affecting the carb vacuum. Doesn't this engine have a split intake? Just out of curiosity does the flywheel have any endplay? This could explain the cutting out when turning also by "floating" the flywheel to one side killing the ignition. Just some thoughts.

Share this post


Link to post
Share on other sites
andrewk
quote:
Originally posted by BLT
Do you think owner up main jet?
Thought of that, but main jet is standard size- The rich jet is identified by 4 dots stamped in the jet face, and this one has none. I ruled out the high altitude jet because the tractor is running rich, not lean.
quote:
The pump can push a lot of pressure if everything is just right. But I doubtt it's the problem. Sounds to me like the bowl is low on gas described when you turn sharp and it starves. The engine will use varying amounts of fuel from idle to loaded wide open. With this in mind is the fuel level in the bowl getting to low when under load? Maybe a restricted fuel flow from the tank. It's also possible that you have a blown intake manifold gasket affecting the carb vacuum. Doesn't this engine have a split intake? Just out of curiosity does the flywheel have any endplay? This could explain the cutting out when turning also by "floating" the flywheel to one side killing the ignition. Just some thoughts.
Been thinking about the float level, and I did try both high and lower than normal settings, before going to the factory recommended setting. I thought that maybe the fuel was sloshing and closing off the bowl vent, causing it to die, (I have seen Al do this to a 725 Grasshopper,in a parade, its fun to watch;)) but it doesn't seem like it is pumping enough fuel to do that, yet it runs rich and carbons up plugs. Fuel pickup is a straw type that goes in the remote tank that is lower than the carb. I have pressure tested this fitting, and made sure it was not restricted. It does have the 'split' intake, in that the carb mounts in the middle, and there are two intake mounting points, but the gaskets are new, and I checked for leaks using some carb cleaner. Haven't checked the flywheel (didn't notice anything out of the ordinary when I had it off), but I will in the morning, as well as how full the bowl is getting now- Hopefully I can tell by shaking the driveshaft, and not pulling the engine again. Thanks all for the suggestions!! It always helps to have some input to ensure all bases are covered! Andy

Share this post


Link to post
Share on other sites
rsnik
Hah! I have a 422447 Briggs twin in a '96 Murray 48 inch deck I bought new. All my Simplicity tractors have died (don't have that "one hour" to pull the Briggs out of the 7013 and replace the flywheel key.) So, the very long furloughed Murray comes out of the shed. Fresh gas and plugs and wildly surging RPM's. Obviously the fuel pump. Tried to bring the shrunken diaphrams back to life with WD40 because I can't get parts today. No joy. Have to leave day after tomorrow for an extended sailing voyage with my 3 son's. All my tractors are dead. I think I can get my son's friend up the street to mow the monster lawn. Amazing to hear real mechanics talk about any engine, but really amazing to hear you talk about the same engine I was working on today. I got it to work perfectly for a little while but then the fuel pump failed for good and it was all over.

Share this post


Link to post
Share on other sites
andrewk
Glad to hear yours is a bit easier than this one!! I should add- I also replaced the plastic pump piece as well, as I thought that perhaps there was a hairline crack for it to suck air or something. Tomorrow it will be man vs. machine, and man will win with a clear head and lots of patience, and maybe a big hammer too, lol:D

Share this post


Link to post
Share on other sites
BigSix
Can you bypass the pump, and rig up a remote, gravity-fed tank (on a mast of some sort, if need be)? If this eliminated one or both problems, that might prove illustrative. And if it ran unchanged, perhaps it would help rule out incorrect fuel pressure/bad fuel pump? Just a thought.... Peter

Share this post


Link to post
Share on other sites
andrewk
Well, today offered no progress, after trying and double checking all suggestions, but all fingers point at the carb, So I have decided to just replace it. After all, if it looks like a duck, quacks like a duck, and has a bill like a duck- then it's probably a duck, right? Thanks all for the help, I will update when I get it fixed.

Share this post


Link to post
Share on other sites
PatRarick
quote:
Originally posted by andrewk
quote:
Originally posted by BLT
Do you think owner up main jet?
Thought of that, but main jet is standard size- The rich jet is identified by 4 dots stamped in the jet face, and this one has none. I ruled out the high altitude jet because the tractor is running rich, not lean.
Regardless of the mark as to size of the main jet, it could still be too large. Possiblity that the current owner, a previous owner, or another mechanic could have attempted to clean it at one time using something that enlarged the hole.

Share this post


Link to post
Share on other sites
andrewk
quote:
Originally posted by PatRarick
quote:
Originally posted by andrewk
quote:
Originally posted by BLT
Do you think owner up main jet?
Thought of that, but main jet is standard size- The rich jet is identified by 4 dots stamped in the jet face, and this one has none. I ruled out the high altitude jet because the tractor is running rich, not lean.
Regardless of the mark as to size of the main jet, it could still be too large. Possiblity that the current owner, a previous owner, or another mechanic could have attempted to clean it at one time using something that enlarged the hole.
Hmmm... That's one thing I have not thought of!! I'll order the jet too, and try that first! Thanks for the great idea, and I'll report in once I get the part- Thanks again all, Andy

Share this post


Link to post
Share on other sites
andrewk
Well, thought I should give an update. Jet came in today, replaced it, and it ran better, sort of. It went from overly rich to leaning out. I thought that was interesting. Anyway, I noticed that the pleated filter I had used in the tuneup was not full of fuel. I got a new one out, and compared it to the round screen type, and put a round screen type filter on it. No change under load, but sitting on the shop driveway it sounded nice. I decided that perhaps I needed to raise the float level, so I did. Much to my surprise, it was not level as I thought it was. So I set it to level, which is factory spec. Put it back together, and voila, the original problem returned. A nasty, rich sputter. I tried many different float positions, but never could get one to make it act normal. My decision at this point is to replace the carb. Not sure why I was so adamant about trying to work with the one on the tractor, but perhaps it was because I saw no justification that it was bad. There is no corrosion, but it did have some dirt in it, so maybe a passage is clogged or eroded. I hope that this fixes it. Luckily for me, the customer that owns it is a very nice, and patient person. Thanks all, Andy

Share this post


Link to post
Share on other sites
B-16_IC
I really hope that does it for you! I know how you feel, I once thought I was a wiz at flathead B&S diagnosis, until I met up with a JD 111 that I could not fix. I chalked it up to being cursed for being in a green mower.:I

Share this post


Link to post
Share on other sites
andrewk
BINGO. Turned out to be a porous carb body. I noticed today while I was running it, that the carb seemed to be "wicking" liquid. Turned out to be fuel. I painted the carb with some primer to try to seal it, and it ran better than ever, but still sputtered. I called the customer, and he elected to not fix the mower. (Carb is 138.40) But it is finally going away, so I can quit dreaming about it. Not sure what caused it, but it feels good to have finally licked this one.

Share this post


Link to post
Share on other sites
Guest
This topic is now closed to further replies.
Sign in to follow this  

  • Who's Online (See full list)

    • BruceH
    • Mach1martysr
    • FloridaRich
    • MRR
    • abu507
    • BLT
    • Brettw
  • Today's Birthdays

    1. Andust
      Andust
    2. Noly
      Noly
      (69 years old)
  • Recent Status Updates

    • Paul M.Murphy

      Paul M.Murphy

      Hello glad I got on this site. I hope to upload a couple of photos of my Simplicity Broadmoor 
      Model 707 Tractor. I have replaced all the belts on it and installed a new ignition switch.
      Have a mower deck which was in poor shape , repaced a couple of bushings and welded the
      deck where there was some holes. The tractor and mower deck came from a friend and the 
      mower deck metal was getting pretty thin. Some new metal was put in it and we also undercoated the underside of the deck. This was done by my friend Greg Toulman.
      I have not put the mower deck on the tractor yet, waiting for Greg to come home and give me a hand. Can you please tell me if there is a manual for the mower deck and where I could get one.
      I would also like to get some moon wheel discs as well.
      I will try and down load some photos of the tractor when my wife shows me how to. 
      I really love driving this tractor and also how well it is made compare today's tractors, especially the flexible rear end and the rollers.
      Tell the next time 
      Paul
       
      · 8 replies
    • jbrooks

      jbrooks  »  Talntedmrgreen

      Josh
       
      folowing  this from a link at the downloads.  I just rescued an AC 920 with the lambodini diesel. I can' t download  yet .  Where did you find the PDF copy you posted. . I would like to figure out how to adjust the injection pump. 
      I assume it's a bosche, correct
      · 0 replies
  • Adverts

×