Briggs-Mower idles fast then slow

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  #1  
Old 06-02-07, 05:18 PM
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Briggs-Mower idles fast then slow

Hello!
I have a 4 hp Briggs push mower Model #110982, Type# 3211-01, Code# 85013004
After I get it started and set on fast mowing speed the thing revs up and down. I have rebuilt and cleaned the carb and also have messed with the air mixture screw and put it at all different turns. I got it running pretty good with about 3 turns out and it used a tank of gas in 5 minutes or less. Cleaned out air filter, gas tank, and muffler. I have the air filter off when running. When I put the air filter holding screw in without the filter the thing acts like it is being choked out and dies. When I put the air filter on and just hold it in place it doesn't make any difference as it still revs up and down. I thought I was having some success when I had the throttle at half way but, then what good is that for mowing? Any ideas on what I can do next would be greatly appreciated. This is a one spring governor model and old with the carb bowl being on top of the gas tank and the self propel being on the back wheels. Thanks!
 
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  #2  
Old 06-02-07, 06:14 PM
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This is a Pulsa Jet carburetor and is prone to warpage. This sounds like your trouble and there is a repair kit available but I can't recall the part number right now. I'll be in my shop tomorrow and have a look and let you know the number.
 
  #3  
Old 06-03-07, 05:24 AM
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Thanks and I will be looking forward to the info!
 
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Old 06-04-07, 06:48 PM
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Sorry, decided to go to camp rather than work on Sunday. The warpage repair kit is Briggs part number 391413 but can only be purchased in a package of ten which is part number 4184. If you can find a Briggs dealer in your area that has these kits, they should certainly sell you just one single part, not the bulk number of ten. But even if you must to get the job done, the price is under $5 for the ten count. Ideally, you'd like to find a dealer that has one so that you can bring the carb and tank in with you so that they can point out the exact location of the installation of the repair kit. I'm sure, if needed, I can walk you through the install.
 
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Old 06-05-07, 06:40 AM
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Thanks Puey and I sure don't blame you for going to camp instead of work! I am off to get the part now. I'll let you know how it turns out.
 
  #6  
Old 06-05-07, 02:00 PM
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OK. It looks like I need to be walked through the install...I put that pin and paper thin washer in the hole next to the main jet on top of the gas tank. Was I suppose to set it or something? Maybe I screwed it up because I read on another site where someone had the warped tank problem and they made a gasket out of a cereal box. Well, I didn't do that but, I took the old gasket and cut out the inside of it (diaphragm, etc.) to add an extra outside lining to help seal any warping. So I get it all back together. I also read the the air filter doesn't need to be on but, the screw should be in six or seven turns, so I put it in. No start or fire. Take screw out and starts right up and runs great...until I push the mower then it sputters and quits. I do it again. Sits there and idles full on great until I push it. So I mess with the air mixture screw again and now it sputters while just sitting there after I start it. I can keep it running full blown by using my hand as the breather. So next I get the bright idea of checking the gas cap by taking it off. Runs better/good/decent with it barely on or totally off. So I poke bigger holes in it and then take out insert in trying to give it more air. Nothing helps. Every time I tighten it all the way down the thing dies. Besides buying a new gas cap, what should I do next? By the way, I am done looking for info on other sites!
 
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Old 06-05-07, 06:10 PM
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Let me make sure the choke is hooked up before addressing my last post.
Thanks
 
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Old 06-06-07, 02:31 AM
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Have you installed a new diaphragm between the carburetor and gas tank? I'm unclear if you did or not. Or, any new parts for that matter?
 
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Old 06-06-07, 06:15 AM
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Yes, I did a total carb rebuild which of course isn't much on this thing so it has all new parts. I may of unhooked the choke/flap lever when I took it off to put the pin in because the choke stays closed all the time now. So, today I will take it apart once again to check it all out.
 
  #10  
Old 06-06-07, 03:50 PM
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Rusted Tank

Choke was good and so was everything else carb wise. What wasn't good was when I drained the gas tank for the umpteenth time, there was a bunch of debris floating around. This thing is rust city. So I took it to a shop and they bathed it in the carb bath and now all the loose stuff is gone. There is still a heavy layer of rust in there which I know over time the gas will break up. What can I do to get rid of it? I got some battery acid left over-will it work? No sense in doing anything until I get that tank super clean so I can rule out the debris factor. Thanks.
 
  #11  
Old 06-06-07, 06:43 PM
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Get yourself a new or good used gas tank. The rust will be nearly impossible to get rid of economically reasonably. The rust should have no effect on the choke operation so I'd be concerned that you may have an air leak at the intake manifold or possibly an intake valve issue.
 
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Old 06-07-07, 06:05 PM
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OK, today I changed the head gasket because noticed some oil/sludge at the top of it when I took the blower shroud off. Also took extra gasket seal off carb. Put it all back together. It started right off and ran real rough. Started messing with the air mix screw. I had put the new plastic insert in. Nothing happening until I tightened it like crazy and then the mower ran like a scalded dog. It was great until I messed with it again and then it quit. Oh, also I can put the breather on now and the screw doesn't choke it out but, I have to take it off to get it started. So now I am pretty sure it is all about that air mixture screw and that plastic part that I don't think is set right because it came out once when I was messing with the screw. The other thing is that I tightened it down so much that now when I back it off it turns easy real quick. It does seem that my surging is gone which was the original problem and now it is just getting it to run full on which seems to happen when I put the super tight on the air mix. Tomorrow I am going to take the air mix out and tap the plastic part in and start over. Any advice? Thanks.
 
  #13  
Old 06-08-07, 02:21 AM
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I'm thinking the carburetor warpage (If indeed present) is excessive and the repair kit may not be enough to get you going. I'm now thinking you need to forget this carburetor and look for a new or good used carb/tank assembly. As far as the adjusting needle is concerned, this must be installed correctly with the flat side of such going down, into the carb body and using a light coat of WD-40 on the o-ring to help it slip into place.
 
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