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Post by mangetout on May 19, 2022 10:10:34 GMT 1
I've got a mower problem and don't know how to fix it. It's a sit-on with a Briggs and Stratton engine. She starts and one of 2 things happen. Either she stalls almost immediately, or sometimes she goes for a few minutes and then stalls. I'm new to mechanics but trying to learn as my husband is no longer able. I've checked the fuel line, not blocked. Put in a new spark plug. Cleaned the air filter. Haven't checked the fuel filter and there is some residue in the fuel which came out when I checked the line. Haven't touched the carb. Any ideas guys?
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Post by Polarengineer on May 19, 2022 10:23:31 GMT 1
You said it. Check the fuel filter. If some gunk came out of the fuel line (Possibly water condensed in the tank) then you should remove and clean the carb float chamber. Watch this video, fortunately it is in English UK and not terrible American.
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Post by annabellespapa on May 19, 2022 12:20:49 GMT 1
I have two Briggs and Stratton engines, both 12.5 horse power and fixed to a McCulloch and an Alpina ride on mowers and both have to be started differently, one I need to pull the choke out full but as soon as it fires up I have to push it in or it will splutter and stall the second likes the choke out on full for a couple of minute, once warm the choke is not required for restarting, hope that helps
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Post by hal on May 19, 2022 12:51:12 GMT 1
You are going to get as many different suggestions as there will be replies from an armchair, and even then none will be right! I agree with annabellespapa above - with Briggs motors, each one seems to have its own peculiarity.
Do you have anyone locally on the ground that knows about these things? I agree the fuel filter is a possibility, equally it could be inside the carburettor - especially if you noticed some muck in the fuel line. Do you get any warning if it is about to stall, or it just stops for no reason..? Does it start easily after it stalls?
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Post by cernunnos on May 19, 2022 13:11:16 GMT 1
If you have muck in the fuel line , then there is probably muck in the fuel tank. I have no experience with Briggs motors ,just MF, but it sounds like a fuel blockage .
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Post by chrisell on May 19, 2022 17:24:57 GMT 1
Did you leave fuel in over winterFuel filter first but..
I had to replace the carb with similar issues on mine. If the engine runs at any idle speed you can try one of the carb cleaners you add to petrol or you can clean the carb (or buy a cheap Chinese one and spend a quarter of the time)
There are usually local mobile mechanics around - I paid 120 ISH for a basic service. Or local motoculture although they wanted 100 for collection/delivery and they're 2km away - and if I hadn't been so irritated at that price I had thought about driving it there.
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Post by landmannnn on May 19, 2022 18:31:31 GMT 1
Similar to others, I have a couple of ride ons with 11 and 12hp motors.
Suggest you turn off the fuel, remove the float chamber (just unscrew the nut on the bottom)
Turn the fuel back on and see if it runs out, if not likely a fuel blockage.
Actually I replaced the carbs at €30 each from eBay, saved messing about.
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Aardvark
Non-gamer
Living in soggy 22 and still wondering what's going on.
Posts: 2,172
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Post by Aardvark on May 19, 2022 19:48:54 GMT 1
I have also worked with B&S engines from 11 to 14hp. The problem is most certainly to be fuel related as suggested above. Do as Landmannnn says and remove the float chamber and drain off the water and wipe out the sand/rust/varnish sludge that you find inside. A word of warning. The extremely thin rubber seal between the float chamber and the carb body is easily broken so go slowly and try not to damage it. They are pretty expensive for what they are. On some larger/later engines there is a solenoid valve instead of a simple bolt holding the chamber in place. Sometimes it is this solenoid that either fails or sticks and prevents fuel from getting into the carb. I have recently had this exact problem.
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Post by pcpa on May 19, 2022 21:48:48 GMT 1
My money is with Chrissels proposition if its the first time it has been started since the winter lay up and especially if it wasn't run dry of fuel before laying up.
I have spent the last few days coaxing back to life my Stil hedgetrimmer, Stihl chainsaw (1960's vintage) and a Ryobi strimmer which have not been used for several years but were ran dry of fuel, all needed the carbs cleaning, the Ryobi had a perished fuel line from modern fuels yet the 60's Stihl with its made in Merica Tillotson carburettor was still OK, the chainsaw started but wouldn't run correctly after severl carb cleanings and now wont start at all to set the mixtures.
I still have an Italian disc cutter and a 60's dammeuse with a Villiers engine to resurrect, the latter may be past redemption after being on loan to an abuser.
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Post by hal on May 19, 2022 22:58:40 GMT 1
You have not come back to my questions, so I am going to assume a few things and suggest you carry out a few 'musts' that should be done once a year regardless with Briggs engines, whether primer or auto choke type.
Change the plug which you already have done. Assuming when it does run, it is smooth, then magneto should be fine. Unblock the vent in the fuel filler cap - a fine wire or a blast of air. Take off the carburettor bowl and look at the bottom. Chances are there is water there that is being sucked up. The brass nut that holds the bowl on is the main jet - run a fine wire through it or blast it with some air. If you have difficulty after this, then, you do have a problem.
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Post by cernunnos on May 20, 2022 19:59:28 GMT 1
I've got a mower problem and don't know how to fix it. It's a sit-on with a Briggs and Stratton engine. She starts and one of 2 things happen. Either she stalls almost immediately, or sometimes she goes for a few minutes and then stalls. I'm new to mechanics but trying to learn as my husband is no longer able. I've checked the fuel line, not blocked. Put in a new spark plug. Cleaned the air filter. Haven't checked the fuel filter and there is some residue in the fuel which came out when I checked the line. Haven't touched the carb. Any ideas guys? Did you get it fixed mangetout?
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Post by pcpa on May 20, 2022 19:59:53 GMT 1
I have heard my new neighbour (elderly) trying to start his vintage ride on mower a few times so today offered to help, cue another afternoon of carb cleaning!
This was indeed Briggs & Stratton 12hp with a carburettor as Hal describes and had a similar problem of starting but dying immediately, I found that the link rod of the choke linkage had become disconnected from its home somewhere behind the governor plate, he thought the choke was working because it was stiff to operate but that resitance was a seized cable.
I got it to fire up & run by manually operating the choke butterfly but it has a further problem of leaning out when the choke is removed even after removing the carb, cleaning the jets, the emulsion tube and blowing out all the galleries, it had no gasket on the manifold flange to the cylinder head and I am fairly sure the problem is a big air leak there meaning there is not enough airflow to create the depression across the venturi of the main jet.
Tomorrow I will bricolage a gasket but for the OP if your choke linkage has disconnected like this one had it would explain your starting problems so worth a look, and in that regard a question for Hal:
To save me researching on Google do you know where the choke operating rod should connect to behind the governor plate, I cant feel any holes and the end is an open loop that looks like it simply drops over a lever but without taking it all apart I cant see what or where.
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Post by pcpa on May 20, 2022 20:05:42 GMT 1
Another question for Hal, screwed into the brass nut there was what I thought was a mixture control screw, the same as on an SU carb but you adjust the screw rather than the hight of the jet, except he was adamant it was a drain screw for the float chamber, I think I was wrongfooted by him as it had a needle point and a spring and washer but missing the sealing O ring it would normally have.
Is that indeed the main jet mixture screw?
I think he wrongfooted me and that is why it will only run with the choke strangler partially closed.
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Post by hal on May 20, 2022 22:36:53 GMT 1
I do not know the Briggs engines intimately or outside the ones I have had. However I understand the carburettor principle has remained the same since Methuselah with the exception of one they have that sits on top of the fuel tank and is a diaphragm type.
As I understand it, the common ones have the float bowl secured with a central brass bolt with a jet in the centre and two holes either side that feeds fuel into the jet that in turn is sucked up by the carburettor. I only know of three variations - one, just a bare bolt with holes as described. Two, an adjuster in the centre of this bolt that can raise or lower the jet seat (maybe you have this type) and the third, on modern Briggs engines, there is a large solenoid on the bottom of the nut that closes the jet when engine is switched off. Regardless though Briggs carburettors are so basic they just need cleaning.
If gaskets and/or seals are missing, then of course there are issues.
I cannot ever remember changing out an auto choke rod - but the rod will go through the engine cover and attach to a bi metal hinge situated near the cylinder. You will, I think, only find this by removing the engine cover.
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Post by hal on May 21, 2022 7:01:02 GMT 1
Loads on Youtube I see. You will easily find a clip on your actual model.
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