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8N CARB ISSUE

dan I have a 8N that ran when it was parked last fall but will not start and run now. I have completely disassembled the carburetor, boiled, cleaned and blown out all ports 2 times. All fuel filters have been cleaned and I do have good spark. It will fire but only if I seal the air intake with my hand. It pulls a good suction then fires and starts running, if I let in only a tiny amount of air, let in to much air and it quits.

Any ideas?
Dan

Jim Loveridge The only thing I can think of is to check that the manifold isn't cracked and all the bolts are tight. What about the gas? Could it be bad? Even though you cleaned all the filters, are you getting good flow? But it seems like if there wasn't, it wouldn't even run with your had over the intake.

Bob will come along soon and throw in some more ideas.

Bob G It would be nice if you had a different carb you could try. Do you get good flow thru the carb when you pull the drain plug? I would measure it. let it fill a pint jar and see how long it takes to fill it. Should fill a pint jar in 2 to 3 minutes. I had one that the filter screens were all clean but the stand pipe in the tank was plugged.

If you get good flow then I would go thru the carb again and run a wire thru every passage way. It would like something is blocking the fuel someplace.
a good spark means that it will jump a 1/4" gap!
good luck

dan Fuel delivery was fine 1 pint in just over 2 minutes. I replaced the plugs with a new set of AUP 437 plugs and have great spark. Now it's back to the carburetor but I need to find a good set of wires to clean the passages. Up to now it,s only been air.

Dan

Bob G You are making headway. as a side note,i would double check the firing order. 1,2,4,3 front to back.

some people use welding tip cleaners, I use whatever I can find for wire!

you will get there, keep at it!

Jim Loveridge If I'm wrong about this let me know, but if it will run while you are completely blocking the intake with your hand, it's pulling air in from some where else. It was running fine last fall, right? What could have happened to it during the winter? Were kids playing on it and fooling around with it?
Bob G Jim does not the fuel get sucked in at the venturi and the air has to passing thru it in order to work? Sure would be nice to my hands on some of these problems myself! Real hard to diagnose online sometimes. Little thing ands big things et overlooked! still fun tho!!!
Jim Loveridge Bob, he says he is getting good suction at the intake, but the engine won't run unless he holds his hand over the intake, so it's getting a close enough air/fuel ratio to run. Where is the air coming from? In theory, you are correct about air having to pass over the venturi I think. But perhaps in an up-draft carburetor, all it takes is vacuum.
Bob G What pulls the fuel out of the bowl is the reduced pressure created by the air speeding up goin thru the venturi, but like you say maybe it is the extra vacumn sucking it out.
dan Let me try to add more clarity.

It ran fine when it was parked and covered last fall.

It won't start and run with the intake completely covered, but it will pull vacuum and fuel. If it is covered and you crank, it starts to pull a vacuum and fuel to a point where the engine wants to fire. At that point if you remove your hand it will start and burn the fuel that has been delivered when covered and then quit. It will run only 2 to 5 seconds, but if you continue to cover the intake and let in only a tiny bit of air you can keep it running longer but much slower. About 15 seconds is my record.

By the way you guys are welcome to come over and see it for yourselves, coffee is on me.

Dan


Bob G What you just said makes more sense. I think something is blocking the fuel in the carb.

If you are near Portland Oregon, coffee always works!

Jim Loveridge Dan, thanks for the re-fresh of the problem. Have you tried spraying some starting fluid into it while cranking? If it responds to that, then it might be stale gas or do you use gas treatment? Where are you located just for grins.
dan I am a long way from you Bob, afraid the coffee may get cold on the way over from Grand Rapids MI. It's new fresh gas Jim, but I am still working over the Carb. By the way Jim, what part of the world you stationed.

My next step is to check to see if it is covered under my homeowners fire insurance. (lol)

Bob G Darn, thought I was going to a free cup of coffee!! Jim is a bit closer but not much!

When you are running wires thru every thing don't forget the main jet. I got a rebuilt carb sitting here in front of me that I need to install one of these days and see if it will work or not. Been waiting for one of the others to stop working but they keep right on a going. I don't run them much but have fun with them when I do. a bit of mowing and road work. I also have JD MC that I like to play with.

Good luck!

mark sr Hi Dan, it is a small world. While I've lived in tenn for the last 20+ yrs I grew up in GR. At least these old tractors are simple to work on compared to a lot of the new stuff.
Bob G http://www.ntractorclub.com/howtos/pdfs/Cleaning-Carbs.pdf

Check this out!

dan Ha thanks for the shout Mark. when did you grow up and where did you go to school? I went to Godwin and graduated in 63.

Ha Bob, you are a great source of information. I have been looking for something like that report for over a week. My fingers are crossed.

mark sr Dan, I went to Central High. I left GR back in 72 after I graduated, haven't been back since the mid 70's. My mother and brothers now live in east mich.

Between Bob and Jim you can find out most anything you need to know about these old fords!

dan Well guys, I gave up and ordered a new carburetor. I will let you know the verdict turns out to be. But regardless I just want to let you guys know how great it is to have a resource like you around. THANK YOU for the help!!!
Bob G If the old one is a MS carb, don't throw it away or throw it in my direction!
Bill I am having 8N Ford issues also. I have to crank and crank to get my tractor to start, but once it is running, if it doesn't die, it runs like a champ until I shut if off and try to start it again....Any ideas on the problem? Anyone?

Bill



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