BN Troubles

OK, guys, I need a little help. My ol' BN hasn't been started for about four/five months. Always started easily before. It cranks fine. I'm getting spark, and getting gas to the carb. If I let it sit for a few minutes, it'll fire and go for about one full second, then shut down. Any ideas?
 
Several things could be in play here one gas low is not what you think. Check flow 2 float not allowing fuel flow through it or plugged air cleaner body not letting air in to fire. Points or condenser could be working part time ignition switch could be not making good connection. You 't don't say if it is a mag or distributor some possibilities there too.
 
I would say it's the condenser..... Absolutely drive you nuts, chasing what appears to be a fuel issue......
 
How are you determining it has adequate gas flow? There are drain plugs on the carbs that is where you need to check for flow. Get a glass jar to catch it in so you can determine if the fuel is clean. At first it will be emptying the carb bowl which holds a cup or so but then should continue to flow steady and not slow to just a dribble. If fuel flow is low you need to check the elbow fitting in the carb the fuel line screws into.the carb has a fine screen you need to check off that is clean. It should also flow well out of the line from the tank.
Edit to add..
How area you determining you have spark? Just opening the distributor and see a spark in there when you move the points is not telling you the spark is getting to the spark plug. You need to see if spark is getting to the actual spark plug. If you have a new spark plug is best or if not rob a plug out of another running machine like your lawnmower. Plug one of the spark plug wires on it and take a leather glove and hold the plug against a metal part or the engine. You should get a consistent spark across the plug gap of each plug while turning the engine with the stater. If not consistent you need to find out why. Is your description accurate of it only running for ..one.. second accurate? That is not very long. What do the spark plugs look like? Are they black and sooted. If so replace them or clean them. Clamp hex of plug in a vise. Spray with carb cleaner and wire brush then blast with compressed air.. then repeat again. Then test for firing as you did with the test plug above.

This post was edited by used red MN on 09/18/2022 at 10:44 am.
 

Also check flow out of strainer on the bottom of fuel tank. My BN had a problem where it would run good for a long time them quit like it ran out of fuel. Let it sit for some time and it would fire right up.

Turned out it was flecks of sealant in the tank coming off and plugging the valve in the strainer. Ended up putting a piece of fine screen over the inlet to the strainer and it's run good for over a year.
 

Like they say 90% of carburetor problems are ignition problems or is that 90% of ignition problems are carburetor problems?

Point being sometime you have to go by process of elimination and go from there. If it quits and you can check for spark by holding a pug wire near the block and crank it over and it has spark move over to the fuel side of things.
 
That's exactly what I did. The spark seemed strong, so I went to the carb. Was getting fuel to the carb, so I took out the screen
filter and cleaned it and it's running great again! Drove it for quite a while today, with several shut downs and starts. No
problems. Thanks!
 

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