John Deere A misfires when I hit a bump/odd sediment bowl b

pmarkel · Sep 26, 2019

Posting a picture here of an odd air bubble at the top of the sediment bowl of my 49 A. Been having trouble with the tractor misfiring when I hit a bump or at high idle under load. Also makes a big pop when you engage the clutch. Idles nice and runs nice otherwise. Thinking I need to soak the carb again and doubt this has anything to do with the sediment bowl but I thought it looked odd. On all my other tractors the gas fills the bowl completely. Incidentally, I took the aircleaner system apart this spring and soaked it and that corrected some of the occasional hesitations but not all. Thanks,

Pete

susandiane · Sep 26, 2019

These old eyes can't really see the air bubble, but there should not be one. The fuel comes in the center from the top, squirts down to the bottom where the U-turn throws out dirt and water, then rises back up and goes
through the screen to the discharge side. If there's a bubble, something's wrong. Open the drain on the carb and see what happens. There could be an air lock in the line that's keeping the gas from this down, up and
out path. Opening the bottom of the float bowl, or even the plug at the filter on the side of the carb should let gas flow freely through the sediment bowl and out in a solid stream, no bubbles. Now that I think of it, there's
another possibility . . .On some tractors there's a little wad of what looks like machine turnings stuck in the hole in the tank. Filters out clods and frogs, I guess. If gas doesn't come streaming out with bowl plug
or carb filter plug removed I'd check for that or something like it in the tank. Could also be a leaf or dead bug. Let us know--that's strange!

Joel Sanderson · Sep 26, 2019

My A misfires when I hit a bump too. Just thought that was an A thing.

I have a sediment bowl that leaves an air bubble in the top unless I get it out by loosening the bowl and getting it out past the rim. It's on a stationary engine and not a tractor.

Have you tried adjusting the carb any? I'd guess you're running a bit lean, but I'm no expert.

Lon in NE · Sep 26, 2019

Loosen the screw that holds the sediment
bowl on , crack the bowl loose and let
the air bleed out. Gas coming in should
force the air out. Then retighten the
bowl screw and hope it doesn't drip.😀

pmarkel · Sep 27, 2019

(quoted from post at 18:44:43 09/26/19) My A misfires when I hit a bump too. Just thought that was an A thing.

I have a sediment bowl that leaves an air bubble in the top unless I get it out by loosening the bowl and getting it out past the rim. It's on a stationary engine and not a tractor.

Have you tried adjusting the carb any? I'd guess you're running a bit lean, but I'm no expert.

I had tried to bleed the air out by loosening the bowl since I noticed on other tractors that when I took the bowl off for cleaning it would never refill all the way upon reassembly. But it didn't seem to work that bubble out (it's been like this for months). Ran it for an hour, bubble was still there. Now last night I go to pull the carb and see the bubbles gone. Carb looked clean inside. I know about drilling the idle passages but are there any load passages that can be drilled?

Mike M · Sep 27, 2019

Does it puff some black smoke when that happens ? I've had the B do that. The late tractors they raised the float level setting to 3/8" ? can't remember for sure. All the older ones were 1/2" setting. So I use the lower setting on them.

pmarkel · Sep 27, 2019

(quoted from post at 07:09:06 09/27/19) Does it puff some black smoke when that happens ? I've had the B do that. The late tractors they raised the float level setting to 3/8" ? can't remember for sure. All the older ones were 1/2" setting. So I use the lower setting on them.

yes usually the pop is accompanied by a little puff of black smoke

John Deere A misfires when I hit a bump/odd sediment bowl b

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