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Old 01-25-2015, 10:42 PM
1 posts, read 30,103 times
Reputation: 10


It sound like the engine is not getting enough fuel. Is the shut off valve tired all the way on?
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Old 01-25-2015, 11:54 PM
48,519 posts, read 81,563,794 times
Reputation: 17990
Likely you need to rebuild the carb with a kit. That includes all gaskets plus the diaphragm .The first sign that is going in non reed valve engines is at full throttle it surges. In time it gets worse and eventually fails. Basically it can't draw enough fuel with bad Diaphragm.
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Old 01-26-2015, 08:59 PM
2 posts, read 59,993 times
Reputation: 14
If the engine only runs with the choke full on it means you have a vacuum leak and the engine runs too lean with the choke off. Some times a back fire into the carburetor will blow a pressed-in BB out of a drilled passage way. You will not know if the BB is missing cause it will look like another hole in the carburetor. Feel around on the carburetor for a hole with the engine running and plug it up with your finger then open the choke to see if that fixed the problem. If you find the vacuum leak hole you can epoxy it shut with JB Weld. Takes about 24 hours for the epoxy to cure. Also you can find a vacuum leak with engine running by spraying WD-40 around carb. If the engine revs up you have a vacuum leak somewhere. Your other alternative is to get your light weight plastic shovel out and get some good exercise.
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Old 01-28-2015, 10:15 AM
Location: Billings, MT
9,175 posts, read 7,225,405 times
Reputation: 12659
Just a couple of nit-picky things I noticed in this thread.
1. If it is a Sears snowblower, it is doubtful it has a B&S engine. Nearly all of those had a Tecumseh engine.
2. I used to work in the shop for an outdoor power equipment dealer. We worked on all types of snow blowers and throwers, and I NEVER saw one that had an aircleaner on the carb. The paper element gets wet with snow, plugs (ices) up, and the engine won't run!
3. Every year, we got lots of snow machines in that would only run when choked. Every time, we cleaned the carb, adjusted the jets, and it ran fine. Then in the spring, it was lawn mowers. Same thing.
4. Once the passages in a carb are plugged with varnish from rotten gas, there is nothing you can put in the gas tank that will clean them. The carb MUST be removed, disassembled, and thoroughly cleaned before it will work right.
5. WD-40 is not a carb cleaner. Don't waste your time or money, do the job right the first time.
6. Sta-Bil is your friend. Read and follow the instructions on the bottle. It works! Maybe Sea-Foam is just as good, I don't know, I have never used the stuff.
7. If you get a carb kit, and some cleaner, and "rebuild" your carb, but don't have an air compressor to blow the passages out, you are wasting time and money
8. If you get the carb rebuilt correctly, and it has an adjustable needle on the bottom of the bowl, you must adjust that needle valve (main jet) properly or the engine won't run right.
9. If you don't know what you are doing, leave it alone and take it to the shop to start with. Your mechanic will appreciate not having to fix your mistakes!
10. Yes, the problem MIGHT be a vacuum leak, but in all the problems I dealt with on a daily basis, I never found one. The problem was ALWAYS rotten gas!
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Old 02-10-2015, 12:35 PM
2 posts, read 59,993 times
Reputation: 14
On a 1999 Powermate Coleman 15 HP Vertex Generator with a B&S engine the engine would not run smoothly when taken out of the box 15 years later. It had been stored in a garage and never used till 2014. Upon opening the choke fully it would speed up and slow down. At half choke it would run smooth but did not have full power. After several carburetor dismantles I found the emulsion tube was stuck on a burr and needed to be screwed in about 4 more turns. That fixed the problem. On a two cycle moped engine I found a BB that sealed a drilled passage missing making the engine run lean and quit running.
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Old 04-12-2015, 08:50 PM
1 posts, read 29,625 times
Reputation: 10
I have a horizontal shaft 212cc 4 stroke harbor freight motor on my go kart. When I turn the choke off it takes off and will run up to 15mph with out me hitting on the gass. Any ideas I just bout it around 1 month ago
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Old 07-31-2015, 04:38 PM
1 posts, read 28,902 times
Reputation: 10
Was just given a 6250 generator with a 10h.p. B&S motor, because it didn't work.
would run on full choke until it warmed up. I know the problem, but I'm lazy.
So, I removed old gas replaced with 2l new and 1l lacquer thinner. Still took a bit to come off choke, but gradually it came around. Now it purrs as best as a Briggs can.
I don't know the thinner did to the pot metal carb though, but hey, it was free.
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Old 10-04-2015, 03:48 PM
1 posts, read 28,638 times
Reputation: 11
Default Fantastic! thank you!

Thanks to the OP and the many who answered questions.

I have a generator with a briggs 8hp that only ran on full choke.

I took the air cleaner off and float bowl and sprayed the carb liberally with carb cleaner, no change.
fuel filter flushed, tried to run it til hot, no change. I read this forum and went back in.

I removed the float bowl. Up inside the screw port, where the bowl screw goes in, is a narrow hole. I ran a thin peice of wire in there and freed up some blockage. I sprayed carb cleaner through this tiny port, then the wire again. observing the brass tube inside the carb. I did this a few times until carb cleaner blew threw there in a much increased volume. Like it went from a tiny spurt out the end to the full volume of the brass tube.

Generator fired up to full output on the first pull.

Thanks to everyone here. If you have a Briggs that only runs on full choke, it's the tiny brass tube inside the carb is clogged below. remove float, run wire through, flush...perfect!
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Old 02-24-2016, 09:07 AM
1 posts, read 27,726 times
Reputation: 10
I am having same trouble with my 4 wheeler ATV's , wont run without choke engaged. Also weedtrimmer and chain saw ///
I am no guru but no novice either. but taking carb apart , cleaning , in small engines I installed gasket kits and bang , same story . HELP !!!!!!!!!!!!!!
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Old 03-19-2016, 01:21 PM
1 posts, read 27,561 times
Reputation: 10
Cleaned the carburator out several times with sea foam spray added sea foam motor treatment to fresh fuel, replaced all gaskets and still have no luck. Pressure washer only running with choke on. Any ideas? Thanks.
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