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Isleblue65

Briggs running problems

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Isleblue65
My 326431 Briggs (on my 7016H) starts up fine and runs fine until running and warmed up about 45 minutes. At this point it starts sputtering and missing. I've adjusted the carb per the manual, finding the mid point between too lean and too rich, and I believe I have this adjusted correctly. When it starts missing, I have adjusted the needle, but there is no position between too lean and too rich that will eliminate the sputtering and missing. Pulling back on the throttle does make it smooth out. The roughness is only from about 3/4 throttle and up. Once it is cooled down again it runs smooth and strong until I run it for a while, then the rough running starts up again. Any ideas?

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Isleblue65
The stock magneto coil on the flywheel went bad earlier this year, so I replaced it with an automotive style coil. The spark is very strong and the coil is brand new, as is the spark plug, points, plug wire and wires from ignition and battery to coil. I suspect some kind of a carb problem, but not 100% sure.

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Isleblue65
The gas is brand new non oxygenated. I was using the E-85 (Ethanol) fuel before, but read about the problems it can cause with older engines, so went to a pump that sold non-Ethanol. I just filled it with the gas this week and the gas was purchased about 3 weeks ago. If there were a mouse nest under the cover, would you be able to see it without taking off the cover? Wouldn't I have to pull the motor to remove that cover? If the problem is from overheating, then you are right that there could be junk (grass, nest,etc) under there.

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rsnik
Hi Craig, I have an infra red temperature gauge and just got the 7013S red hot mowing tall grass for an hour. On the top of the head I get readings of 240-260 degrees. On the cylinder fins on the front of the engine I get readings of around 340 degrees on the side away from the exhaust pipe which rise to 400 degrees when I get close to the exhaust pipe. The temperature gun I have is a Mastercool Part #52227. It is a common short money model (I paid under $40 for the combo kit with free shipping). If you google it you will find 50 people selling them. Maybe I have a cooling problem too. If any other members take the head and cylinder temp when the engine is real hot I would be very interested as maybe I should take my tin off and clean the fins. Bad news is you do have to pull the engine. Good news is I am putting an engine picker on Santa's list this year. As richp has noted the engine comes out real easy. That is if you have some sort of cherry picker to easily pick the engine off of and gently land it back on the chassis.

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Silver E
The tractors i've collected have been mostly cheap ones some not running units, so maybe not the best care. But i have not taken one apart that wasn't full of grass or something. one 300421 briggs has scratches in the cylinder right where the stuff was blocking the air

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rsnik
I have a Murray with a Briggs 18.5 I bought new and mowed for 10 years with before taking up Simplicity tractors as a hobby. You could pull the tin off that without pulling the engine. I mow large lawn areas as well as dry, weedy areas that I mow just to remove the fire hazard. I used to have to pull the tin at least every other year to power wash and it would be packed with grass debris under the tin every time (the engine would also be running hot). I would imagine the cast iron Briggs would clog up under the tin at the same rate as it is doing the same work.

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Isleblue65
Thanks for the info! Could overheating cause the symptoms mine has? I suppose pre-detonation due to lots of heat in the cylinder could be the sputtering and popping from the carb that I'm hearing. I'll see if I can get that cover off this weekend. The guy who owned my tractor before me wasn't a mechanical guy, and he gave me all of the receipts back to the late '80s when he bought it from someone. The engine was never out of the tractor, and the repairs and tune ups that were done to it never involved removing the cover. If it's ever been removed, it hasn't happened since the 1980s when the original owner still had it. Probably due for a cleaning!

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Isleblue65
Well, today I confirmed that overheating was NOT part of the problem. I started it up cold in the shed and it sputtered at 50% throttle right off the bat. I then removed the flywheel cover far enough to peek in there with a flashlight and everything is remarkably clean. No grass or gunk or nests. I checked the new points and they are opening and closing properly. The spark plug was black with carbon, but this could be from when I was messing with the carb fuel mixture. That's as far as I got before the sun went down. Tomorrow fresh gas is going in. I suspect either bad gasoline or a carb problem. The gasoline explanation could make sense though because the non-ethanol based gas that I just put in the tractor is only sold at a few stations around town, and you can only legally buy it for collectors cars and to put in gas cans for mowers. That stuff probably sits in the underground tanks at gas stations MUCH longer than the standard E85 gasoline that everybody else fills up with. At least I hope that is the answer. I'll report back tomorrow.

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skunkhome
check you points to make sure thay are set at .020". If they are less than that it will retard the ignition. If they are at .020 it could still be retarded due to wear on the plunger and cam. I was having exactly the same problem with mine stumbling upon acceleration and when a load was applied. I was talking to an old auto mechanic and he suggested opening the points a hair to advance the spark. With the motor warmed up I adjusted the points adjustment screw CW then CCW while working the throttle to find the exact point where the engine stopped stumbling upon acceleration. I was careful not to advance beyond that point. Motor runs fine now , never stumbles but there is no sign of preignition. Points gap measures 0.023-0.025".

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Isleblue65
I started out today with new gas, new air filter and new fuel filter. Next, I checked the points. They are at .020". I started the tractor and adjusted the points. No difference opening them up a little or closing a little, except too far in either direction and the tractor stalled out. I put it back at .020" and closed the cover. Now I have a new problem, and it is that the tractor throttle control now does nothing - it stays at idle speed the whole time, but sputters and pops. I am thinking that I possibly hooked up the linkage or springs to the carb incorrectly because the butterfly never moves (it is all the way open all the time) even when I move the throttle lever up and down. Yes, the cable is attached to the arm with the springs on it, but the springs are always in tension, so the butterfly is always open. I don't remember how the linkage should be hooked up and the basic Briggs owners manual shows nothing. Could someone please post a photo of the carb linkage and springs so I can see how they should be attached? Besides this, I am sure there is another problem with the carb, but I'll have to deal with this once I've figured out the linkage. Perhaps the float is full of gas? Thanks

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rsnik
Hi Craig, Did you disassemble the carb linkage? Basically the wire from your throttle slips through the hole in the vertical rods with the tiny nuts on the top end (adjusts max engine speed). The vertical rod attaches to that swing arm that pivots on a cap screw on the side of the block. 2 springs dangle down from the swing arm and attach to the beginning and end of the governor arm. A vertical wire rod attaches to the end of the governor rod and is attached at it's top end to the inner end of the throttle plate rod. Your throttle is not connected directly to the throttle plate, the throttle plate remaining open does not indicate a linkage problem. To quote the maxims of UCD, if it seems like spark it's probably fuel and if it seems like fuel it's probably spark. Three things are necessary for the engine to run: compression, spark and fuel. I am wondering if you should begin at the beginning and perform the tests to determine what is working in terms of compression, spark and fuel. A compression test will tell you if the piston and rings are making enough compression. Test while the engine is fully warmed up. A leak down test will tell you if the valves are sealing. To do this you remove the spark plug and get the piston close enough to top dead center that both the intake and exhaust valves are closed. You secure the engine by clamping the drive shaft or by whatever means so that it will not turn over and attach an air hose with the appropriate threaded adaptor to the spark plug hole and inflate the cylinder with compressed air. If you hear air hissing out of the carb, your intake valve is not sealing properly. It is damaged or out of adjustment. If you hear air hissing out of the exhaust, your exhaust valve is not sealing properly for the same reasons. Willy has commented on the coils of battery ignition conversions failing. I would use a decent spark checker and check the spark in low light conditions (so you can really see the spark). Observe and determine that the spark is not only strong but also smooth and does not become erratic as RPMs increase. The new sputter and pop trouble may indicate that the coil is rapidly getting worse. Take the points cover off also and watch (in dark or low light conditions) to see if the points spark erratically as the RPMs increase (the points plunger may be worn or damaged or the adjustment screw threads stripped). If you have excellent compression and spark and the engine is not overheating you have eliminated those areas, at least, as possible sources of the trouble. Dave has commented that a Briggs engine repair manual is an invaluable tool. I managed to find and buy a factory repair manual for your tractor and mine (doesn't say anything about the engine itself, though) and I think a Briggs engine repair manual is next.

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Isleblue65
John, Thanks for all of the information. I ordered a carb rebuild kit from Jack's yesterday, and will be calling them on Tuesday (Monday holiday) to add a Briggs repair manual to the order before they ship it. It's something I've been meaning to get for a long time. I did remove the carb to gain better access to the flywheel cover, belt pulley and driveline, and it makes gas tank removal easier. The linkage came off, but from your description I got it hooked up properly again. Your method of determining the root problem is a good one, and I will follow it. One question I have before the manual arrives is: Does my Briggs model have adjustable valves? If so, how would I go about adjusting them if it turns out they need it? I will

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rsnik
Hi Craig, This is an archived post authored by Rod about the governor. "Have you tried adjusting the governor? To do this, first move the governor linkage till the carb is at full throttle to see which way the governor shaft turns. Then take the clamp on the governor rod loose. Push the throttle on the carb to the full-throttle position. While holding the carb at full-throttle, rotate the governor rod as far as it will turn in the full throttle direction. Tighten the clamp while holding the governor rod and carb in this full throttle position. This is one governor adjustment that many people overlook. It is critical to correct operation. An easy adjustment but as I say, most times overlooked. It usually is not necessary, but I have owned two engines that were acting really weird, and both times this governor adjustment ended up being the problem." Your new manual is going to give you better info than me on your 326431 valve adjustments.

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Isleblue65
Thanks for that governor info John. I adjusted the governor per the instructions and it was actually in adjustment. No changes necessary. So this leaves me with either a carb problem or a major mechanical problem with the valves. Fuel is definitely getting to the carb, and I saw fuel leaking from the intake to head gasket area when I had the choke pulled. As mentioned before I think, I pulled the spark plug and checked for spark, and it is strong and consistent. It was a little hard to see the spark down at the points. I can barely get it to start now, and when I do there is zero change from idle speed no matter what I do. It shakes and chuggs, and then stalls out after a few seconds. How did the tractor go from mowing the lawn beautifully one day to running good for 45 minutes and then chugging the next, to now barely running at all, and all motor controls are rendered useless? :(!:(!

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andrewk
Sounds like it is running way too rich. Have you tried leaning out the main jet again? If you had it apart, and are you sure everything is back together right? I would put money on the carb, hopefully the rebuild fixes it. Andy

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Isleblue65
Andy, I have tried leaning it out to the point where it backfires and then stalls out. The idle never smooths out between too lean and black smoke rich. It won't start without the choke on either, and that's the only time I saw the fuel leaking from the intake gasket area. Usually I only have to leave the choke on for a few seconds after starting. Then it runs great with it off and I don't need it on again to restart the tractor for that mowing session. I'm really hoping that the rebuild fixes things. Hopefully it's just a bad main jet or poorly adjusted float or something else obvious.

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boox
Before you do all the chasing around for a fix, this is about the same problem I had and inquired about here on my 3410S...after some messing around, I installed the NAPA electronic ignition module or what ever it's called, and the machine now runs like a bear. Just my .02 Cents Mb

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Simplicity314
Craig..I had a similar problem, and a suggestion by BLT actually resolved it (or got the idle in the ballpark anyway). It turned out to be the link from the governor to the carb throttle. It was out of adjustment because of wear, but you can see if it's the problem by SLIGHTLY bending that link so it is longer/shorter and hopefully get it within spec. It turned out the hole on the throttle shaft was slightly ovalized and the throttle shaft was slopping/traveling too far.

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Isleblue65
Mark and Jim, Thanks for the ideas. Mark, I bought one of those Napa electronic ignition modules but quickly realized that your magneto on the flywheel must be working properly for them to function. My magnetron had a short - which caused all kinds of running problems at the beginning of this summer - and rather than pull the motor to replace it, I converted to an automotive style (Kohler) coil, which the Napa ignition kit will not work with. See this thread: (Edit: I guess HTML doesn't work on here) http://www.simpletractors.com/club2/topic.asp?TOPIC_ID=80434&SearchTerms=magneto Jim, I will check out that link from the governor to throttle once I get my parts and get back out there this weekend. I suspect however that the problem goes much deeper than that because it is so far from running right that I think it's got to be more than just linkage. I can manually move the throttle open and closed, manually move the governor arm, manually move the throttle cable and linkage and manually move the choke, and none of these things does anything to make the tractor smooth out or run faster than a very rough idle speed. I got the manual on it's way too. That should be a big help. I'll post back on my progress. Craig

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UCD
Gaskets, Gaskets, Gaskets, Carb base gasket, manifold gaskets, when cold these gaskets are sealing when run for any amount of time metal expands and warps causing a gasket to leak. If one of these gaskets leaks vacuum it will act just as you described. I doubt if it is throttle shaft as it would do it from start up. To check this when it acts up spray some water with a spray bottle around the base of the carb and intake manifold if the engine smooths out you have found your problem

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