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skunkhome

Motor still cutting out. Please Help

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skunkhome
I am still having trouble with my 3414s cutting out under load. When cold it will stumble a couple times coming up on speed but as it warms up I keep having to back the throttle off in order to keep it from taking a time out when the governor kicks in. Adjusting the needle valve does little or nothing to help but I can reduce the speed to an idle and it will idle smooth and level at 1200 RPM steady. I hooked a timing light to it and it is receiving consistent spark even when the engine is missing. The tractor is using a little oil but there is no tell tell blue smoke. According to some of the articles I have read I am wondering if I need to go back to 30w HD oil instead of that fancy synthetic 10W30 oil . I was wondering about the springs on the governor... One spring is in a barrel at the end of the lever while the other is in the #1 hole. Is that correct for this application? I am terrified of working on the carburator as someone had already stripped out the cap screw closest to the exhaust and "repaired" it by adding a longer screw with a nut below the flange boss.


I would imagine this is common as I stripped out the same screw when I was a kid working on my B-10. I tried to hide it by drilling and tapping it out for a larger screw and really fouled the whole thing up. I can remember the motor sitting out on the bench with a screwed up carb and my Dad anything but pleased. I have a knack for being able to repair things but internal combustion engines are a bit of a mystery to me. Where should I go next?

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haykarenhardy
I had a real mess with my 712. There was about 1/2 gallon of water in it. Drained the fuel, replaced the gas line which was also bad. Cleaned the carburetor which was full of goo. You do not have a fuel pump but I think that was where I got some trouble to. You might try sea foam motor treatment and some Iso Heat for water. I have used sea foam all spring and now the motor is running better every time I mow. It would cut out also, no amount of adjusting would cure it. Stan

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skunkhome
quote:
Originally posted by haykarenhardy
I have used sea foam all spring and now the motor is running better every time I mow. It would cut out also, no amount of adjusting would cure it. Stan
Stan, So "sea foam" is the stuff! I am looking for any way to avoid taking the carb off or apart. I have already cleaned the tank and installed a fuel filter (did not have one when I purchased). Thanks!

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MrSteele
I think I would look for air leaks around the carb gaskets, on both ends of the intake manifold. Does it miss all of the time when you rev it up to above idle? Or, is the miss occasional, with the engine running ok some of the time? Water in the fuel may well be your problem, but, tell us more. For the correct linkage, run a search here for such info, it has been posted many times.

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PhanDad
A possibility: Vapor lock? Might want to try re-routing the fuel line. I never saw a fuel line routed behind the carb (between the carb and block) as shown in the pic. Every Briggs I've seen has the fuel line routed on the outside of the carb, away from the block. Since the problem is worse as the engine warms up, might the fuel line be getting hot and vaporizing some of the gas? Just a few bubbles reduces the amount of fuel available considerably.

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skunkhome
quote:
Originally posted by PhanDad
A possibility: Vapor lock? Might want to try re-routing the fuel line. I never saw a fuel line routed behind the carb (between the carb and block) as shown in the pic. Every Briggs I've seen has the fuel line routed on the outside of the carb, away from the block. Since the problem is worse as the engine warms up, might the fuel line be getting hot and vaporizing some of the gas? Just a few bubbles reduces the amount of fuel available considerably.
Bill, You may have a very valid point there. As I recall now, my old B-10, 35 years ago had the fuel line routed around the front, as at one point, it was interfering with the throttle stop causing the engine to idle too high. That could very well be the problem. I think I will change the routing regardless as I do not like the way the throttle linkage rubs against the fuel line. If my memory serves me right the fuel line came from behind the intake "stack" and around the front of the bowl.

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skunkhome
Success, success! I think. Thanks everyone for all the suggestions, I drained the gas tank, and used the Sea Foam in my carb and fuel. But I was picking the brains of an old diesel mechanic today and I figures that most diesel mechanics at some point worked on gasoline engines. He seemed to think that since the engine idled so smoothly and only cut out when the governor kicked in that the timing was probably retarded and that I might be able to adjust the points and close them down a bit. Well I tried it this afternoon starting at .020" and reduced the gap with negative results. Then I got to thinking that the spark plugs fires when the points open and the primary circuit fails. If I want the points to open earlier then they need to be opened slightly more. I re-cranked the motor and turned the adjustment screw clockwise about 1/2 turn until the motor just stopped stumbling upon acceleration. I ran the tractor for about an hour slowing down to idle then accelerating to full throttle without the slightest hesitation or intermittent miss. I did not detect any knock or signs or pre-ignition. [b]I may have solved the problem.

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PhanDad
Phil, Glad to hear the tractor's running well, whatever the cure. As far as the fuel line routing, all the routing's I've seen on on the outside of the entire carb setup like this:


However, I think with your routing the part of the line close to the engine is near the cooling air inlet shroud and shouldn't be hot. The only thing I'd be concerned about is that there's no "pinch" in the line due to a tight turn which would reduce the potential gas flow at high power loads.

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SmilinSam
I see it looks like electrical tape wrapped around the carb under the air filter base. Did someone remove the breather tube from the block to the carb and just tape up the hole in the carb?

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skunkhome
quote:
Originally posted by SmilinSam
I see it looks like electrical tape wrapped around the carb under the air filter base. Did someone remove the breather tube from the block to the carb and just tape up the hole in the carb?
Yes, someone in their infinite wisdom removed the tube... I have not replaced yet. I know that when I get one I will probably have to re adjust the whole thing over again as the fuel mixture is going to change when I hook it up. I am finding a lot of little shade tree modifications to tractor and motor that make little or no sense.

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skunkhome
quote:
Originally posted by Ragged_ol_64
Explain to the dumb guy, how do you adjust points, and what should the factory gap be? Pics please if you have them.
Josh, Welcome to the site. Who's dumb? You have already indicated that your are smarter than the average just by showing up here. The factory setting for my engine which is a BS 302400 series is .020".


I have in effect advanced the timing a bit by increasing the gap to about .023" by turning the adjustment screw clockwise while operating the throttle and stopping just at the point that the engine no longer stumbles upon acceleration. (this needs to be done on a completely warmed up motor.) You will probably need to re-adjust the idle settings after adjusting the points. Josh, If you love these old tractors you need to make the smart move and spend the $10. on a club membership that will give you full access and privileges. It will be the smartest ten bucks you will ever spend on your classic tractor.

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