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mongolio

lack of gas or not?

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mongolio
1977 Simplicity 7016H with single cylinder 16h.p. B&S. Have been having trouble getting it started for the last month. Of course, I had the chains, snowblower & Snow Cab installed when I ran into this issue. S/G is turning, I have compression, battery has been load tested & good, replaced plug, re-gapped & have good spark on both ends of the plug & gas in the tank as well as evidence of it getting into the bowl...... however, I had to squirt a small amount into the cylinder to get it running Wednesday night. Ran & idled great for 20 minutes, so I shut it off. Was able to start it back up 2 or 3 times, all proud of myself for getting it running, I retired inside for the evening. Went out last night & same issue, turning over but no ignition. How is it that it can't get enough gas into the cylinder for ignition, yet when I force it in & get it running, there is enough supply to keep it running? Plugged jet or not?

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HubbardRA
Another thing to check is the choke plate. Some carbs have a small spring loaded diaphragm that is supposed to open when the engine starts to prevent flooding. The springs tend to break and the diaphragm falls off. If this happens then there is a 1/4 inch hole through the choke plate at all times. Usually when this plate falls off, there is not sufficient vacuum to pull enough fuel into the carb and start a cold engine. I rebuilt a couple carbs last summer and had to go back through some old parts and find two choke plates that still had the diaphragm in them. I have also used two washers (one on each side of the plate) and pop-riveted them together to close of the hole in a plate. The diaphragm can be totally eliminated, but the engine will start to flood very quickly when it starts. This diaphragm is a very common problem.

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GLPointon
Not choking as stated above or clogged ports in "jet tube" in carb...or as Bob said I also have to start my 7010 in idle. I put full throttle w/full choke, start cranking then pull down into idle and she fires right up... Good Luck sm01

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rokon2813
Air is a possibility too. there are 3 gaskets between the carb and block. If any are leaking enough, you will not have enough vacuum to pull the gas into the engine. a really loose throttle shaft will also give you vacuum problems

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mongolio
Got home tonight & if I hold the throttle idle screw down, which I'm assuming closes the choke plate, it starts up. At least for now I have a solution until I can get it fixed. Thanks for all your helpful tips. Scott

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Tarheel
Turn the choke on all the way. Leave it like that and then loosen the choke cable clamp screw on the side of the carb and pull the choke fully closed. Making sure the choke lever don't move. If you do pull it more, I'd say that was your trouble all along.

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jcrowl
I had the same issue with my B112. This was even after I rebuilt the carb and did the valves. It would only start after holding the throttle shaft to idle and choking it. A few week ago I had enough of it and took the carburator apart. Everything looked good, so I set the float(that was set by the book) so it would get more gas and put it back together. Now it starts right up without messing with anything. I hope this helps, it worked for me... Jim

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HubbardRA
I have found that when I rebuild a carb, if I put in a new throttle shaft, I have to take special precautions or the throttle plate will not completely close on its own. I have to put the throttle plate in the shaft, install the screws (but not tight), then hold the throttle plate tightly closed while tightening the screws. This allows the throttle plate to center itself in the bore and on the shaft when you force it closed. If I don't do it this way, then the throttle will not completely close with the throttle cable. I think this may be the reason that you have to hold the throttle closed to get the engine to start. I have found some that would not completely close, that I wasn't removing the shaft, so I just loosened the screws, held it tightly closed to center the plate, and re-tightened the screws. For those of you who have to hold the plate closed with your hand to start your engine, if you have to remove the carb, try centering the throttle plate, then it should completely close with the throttle cable.

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