70 JD won't start

I installed a diaphram kit on the fuel bowl assembly for my 70 JD gas. I poured in a couple gallons of fresh gas and got it started, but it was missing on Number 1 cylinder, so I shut it off. 'No sweat' because plugs foul up easily on this tractor and it is common for me to wire wheel clean them or sandblast them. Then it starts and runs perfectly for a good number of hours. After I cleaned plugs this is where the plot thickens.

With plugs cleaned, now the tractor won't start. Every once in a while there is just a hint of a fire on one cylinder, but that is all. Now, I have gone from believing that it is not getting any gas to believing that it is flooded. I have taken out the plugs, dried them, and cranked it to make sure if it is flooded, that I have ran excess gas out of cylingers.I have also screwed out the plug on bottom of carb bowl twice, and had gas gush out of it until it drains the bowl. I have checked during cranking to make sure the little spring loaded stem valve is going down to allow gas, because I put in a new rubber washer, and it seems to be working. Anyway, I can't rule out flooding but it is unlikely that it is not getting gas at all. The tractor has always been a good starter and runner, and all I have done is worked on the fuel bowl assembly. Any thoughts?

Have you checked that you have fire at the plugs, check the points too, they may be too close or have a film on them.

Gas gushes out till it drains the bowl---Shouldn't you get a steady flow of gas till it empties the gas tank if you leave it out long enough. Just till it drains the bowl kinda tells me that you have a restriction in the fuel. pull your gas line off and see what you're getting--should have a steady stream there too, if not you need to go a little farther, like pulling the sediment bowl from the tank, it may be partially plugged. If you get a steady flow from the line, then your problem is in the carb. Jet may be sticking or dirt. Just my thoughts, Keith

Even with that oil pressure controlled shut off, if you are able to drain gasoline out of the carb and it won't run you have some other problem . Might be in carb itself. I am not that familiar with that model, but some two bangers have seperate metering systems for each cyl. I have't had much luck with manually depressing that control on the sediment bowl, I just take the oil pressure line off and give it a little air pressure before trying to start so it fills the carb bowl. Then I throw away that system and install a conventional manual shut off sediment bowl assembly. I know, I know, not true John Deere then and you have to remember to shut it off.

Replace the plugs. They may fire outside the cylinder and not fire in the cylinder.

OOPS, forgot about the shutoff on the Deere. My mistake, Keith

I"m leaning towards plugs I"ve cleaned them before in a pinch sometimes it works sometimes not they never work as good as a new plug. There not very expensive so I"d start there if it were me

Agree that you should check to see if there is spark at the plugs.

Started "1011" our 53 Model 70 the other day and it was running on one cylinder.

Pulled the plugs to check if there was spark to the cylinders.

One plug was fouled and replaced it; didn't even bother to clean it.

Usually let the gas run out when shutting down our tractors.

Let the gas run out on "Vernon" our 56 Model 70 and forgot to turn off the switch.

"Fried" the points and it would not start.

Replaced the points and now it runs good.

Had a similar problem with "15" our 53 Model 70 starting and then running out of gas after a couple of minutes.

Pulled the gas line between the sediment bowl and carb and cleaned it really good.

Solved that problem.

Pull the plugs and reconnect the plug wire and hold the plug tight and have someone make an attempt to start the engine. If you don't have a hot blue spark you may have a weak coil. I would use a new sparkplug when trying this. Hal