Good afternoon, have a 9n tractor, it starts great, (when cold), and runs great. After running for a couple of hours if I shut it off and try to start it again it cranks but will not start. I have to wait for it to cool off. Any ideas on what might be happening? Thanks
MickeyDBC
Gold Member
Used to have the same problem with an 8n and it was vapor lock. Since the fuel tank sits over the engine when it is hot it basically boils the gas out of the fuel line and it would not start. I don't think we ever fixed it "right" but I do remember when we parked it at lunch we would set a box fan to blow on the engine so it would start again.
Tractorable
Veteran Member
- Joined
- Feb 15, 2017
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- Marshall, Va
- Tractor
- Tractorless, 2019 Toyota Tundra, 1980 Toyota Land Cruiser FJ40
Sometimes the old coils on the N tractors were known to be affected by heat. They’d work well when cool, but after heating up it partially melt the material inside the coil leading to a weak spark. It’d be enough to run but not enough to start while cranking. Once the motor cooled down the coil would work normally again and the engine would start.
Is your 9N 6V or converted to 12V?
Is your 9N 6V or converted to 12V?
The line is over the engine but there is 2-3 inch space. I can try the fan to see if that helps. Thanks very much.
It is a 6V. Will try replacing the coil. Thanks
AWSubie
Platinum Member
Before you replace coil, try troubleshooting it first. The next time you run the tractor and shut it down and then have trouble restarting, disconnect a sparkplug wire at one of the plugs and see if you get a spark while cranking. If you do then your coil is ok.
If the coil checks OK, check your main jet adjustment screw setting and your idle air adjustment screw setting. First make note of the existing settings by counting the turns required to close each screw. Turn each screw clock-wise until lightly seated (closed) and record the number of turns. Now you have your current baseline and can return to those settings if need be. Then set the screws at the factory initial settings for both screws which is one turn open from the closed position and see if you have better luck starting when the engine is hot.
If the coil checks OK, check your main jet adjustment screw setting and your idle air adjustment screw setting. First make note of the existing settings by counting the turns required to close each screw. Turn each screw clock-wise until lightly seated (closed) and record the number of turns. Now you have your current baseline and can return to those settings if need be. Then set the screws at the factory initial settings for both screws which is one turn open from the closed position and see if you have better luck starting when the engine is hot.
This is great stuff!! It has been a while since I had any issues with my 9N. Last time I did I came to this forum and got the advice that fixed my problem. Thanks to everyone that has responded. AWSubie, I will do as you suggested. Thanks very much.
Tractorable
Veteran Member
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FWIW, the carb settings on my ‘52 8N are 3/4 turn out for both the idle air and the main jet. The idle speed is adjusted on the linkage on the backside of the carb and should be set to about 400rpm. As low as you can go without it stumbling.
Set the idle speed first, then the idle mixture, then rev it up and set the main jet.
Set the idle speed first, then the idle mixture, then rev it up and set the main jet.
DJ54
Elite Member
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- IH Farmall 656 gas/ IH 240 Utility/ 2, Super C Farmalls/ 2, Farmall A's/ Farmall BN/McCormick-Deering OS-6/McCormick-Deering O-4/ '36 Farmall F-12/ 480 Case hoe. '65 Ford 2000 3 cyl., 4 spd. w/3 spd Aux. Trans
If after you do all of the above, and it still does it, and it truly is vapor lock. Do the easiest cure for vapor lock known to mankind, on Ford products. Get you 3, or as many as it takes, spring type clothes pins, and clamp them on the fuel line, in the "hot spot", like in the picture below. You may scoff at the idea, but it works. They act as a heat sink, to dissipate heat away from the fuel line. I can't count on both hands, how many Ford products from tractors, to large farm trucks, from the 50's, up into the 60's I've seen at least 2 wooden clothes pins on the fuel lines.
It worked on my little Farmall A several years back, when bush hogging on a 90ｺ day, working it pretty hard. It shut down after mowing for approx. 45 minutes, like it had dirt in the fuel system, somewhere. After taking the carb. apart, and checking the screen in the elbow going into the carb. and finding them clean as a pin, I deduced it was vapor lock. I went to the house, and got 3 clothes pins, clamped them on, and mowed for another 3 hours in the heat of the day, without a problem.
It worked on my little Farmall A several years back, when bush hogging on a 90ｺ day, working it pretty hard. It shut down after mowing for approx. 45 minutes, like it had dirt in the fuel system, somewhere. After taking the carb. apart, and checking the screen in the elbow going into the carb. and finding them clean as a pin, I deduced it was vapor lock. I went to the house, and got 3 clothes pins, clamped them on, and mowed for another 3 hours in the heat of the day, without a problem.
