8n still has problems

Originally this tractor would not run without the choke 1/3 to 1/2 out. It was hard to start and run inconsistently.
With help from members on this forum, particularly Bruce, The tractor will start and run without having the choke out. However it still has issues,
Still no gas flowing from the carb when it is running and I remove the drain plug on the bottom.
I static timed it per the shop manual instructions, then hooked up my timing light to it and checked it.At 450 RPM's it is at 4deg BTDC. (That is the slowest it will run.)

at 1200 rpm it was 10 degrees,
at 1800 rpm it was 15 degrees. That is as fast as it would go. I should also mention that the timing marks jump very rapidly about 1/2 degree.

With brush hog hooked up it will not mow unless I am in first gear and the throttle is all the way open.

When I had to run it with the choke open, I could mow in 3rd gear.

One thing I am going to do is pull and clean the plugs.
 
(quoted from post at 15:52:05 07/25/14) Originally this tractor would not run without the choke 1/3 to 1/2 out. It was hard to start and run inconsistently.
With help from members on this forum, particularly Bruce, The tractor will start and run without having the choke out. However it still has issues,
Still no gas flowing from the carb when it is running and I remove the drain plug on the bottom.
I static timed it per the shop manual instructions, then hooked up my timing light to it and checked it.At 450 RPM's it is at 4deg BTDC. (That is the slowest it will run.)

at 1200 rpm it was 10 degrees,
at 1800 rpm it was 15 degrees. That is as fast as it would go. I should also mention that the timing marks jump very rapidly about 1/2 degree.

With brush hog hooked up it will not mow unless I am in first gear and the throttle is all the way open.

When I had to run it with the choke open, I could mow in 3rd gear.

One thing I am going to do is pull and clean the plugs.
ooks like you have identified the problem in, "Still no gas flowing from the carb when it is running and I remove the drain plug on the bottom." Now to find the why. Tank venting, in-tank filter, sediment bowl valve & passages in same, sediment bowl screen, line, elbow screen at carb inlet, carb path to needle valve, needle valve/float assembly, and finally the two small holes(only right hole can be seen in picture) connecting the bowl to the bowl drain plug.


 
With the engine running at full throttle, open the main jet & see if it will smoke black. If it doesn't, clean the carb. If no gas drains from it with it running, the drain is plugged up.
 
Have you taken the carb off the tractor & soaked it overnight in carb cleaner? (the stuff that costs $15 & comes w/ a wire basket) And blown out every passage w/ a rubber tipped air gun? If you have, you missed something as JMOR suggested. If you haven't given that carb a good soaking & blown it out, that's your problem. Replacing parts from a rebuild kit doesn't get you much.
75 Tips
 
I soaked it in carb cleaner and blew all the passages out with 120psi air with a rubber tipped airgun.
I am going to try the drain plug test with the engine running at idle speed. I suspect then it will work. Probably doesn't work at 900rpm's because of the higher fuel demand.
 
Yep, all them parts and holes are clean. Actually, mine are a lot cleaner than the ones in the pictures.
My next test is going to be a compression test to determine why plugs 3 and 4 get fouled and wet. Plugs 1 and 2 don't, so I can eliminate everything not engine related.
I am also going to put hotter plugs in to help with this problem.
I suspect the reason I wasn't getting flow from the bowl drain is because I had the tractor running faster than an idle.
 
one other thing i will mention as it happened to me, is check the float level, if its not droping enough you wont have enough gas to run out the float bowl when the engine is running, and you wont have much power under load, as its simply leaning out, push it hard and it will quit running, i have a farmall that did exactly this after i rebuilt the carb, the float level was ok, but the float drop was almost nothing,it would idle and run by itself ok, but ask it to do some work, and it would shut down in a minute or so, i adjusted that and its unstoppable now
 
Bought a compression tester because I like owning the tools I am using. Readings were taken before and after injecting a little oil in the cylinder. Cold engine. I don't like burning myself on that hot manifold.
#1 85 --- 85
#2 90 ---95
#3 105 ---110
#4 90 --- 95

Looks like maybe the valves may be leaking a little.

I was right about the carb. When I idled it down and pulled the drain plug the gas flowed free.
That is a counter intuitive test. Opening the carburetor and dumping out raw gas with the engine running isn't a test I would ever perform on a car or truck engine. Just sounds like a good way to blow something up in a ball of fire.
Put new plugs in it and started it with no choke, and standing on the ground beside it. Sounds like it is running good. Going to take it out and see how well it will pull the brush hog through ironweed.
 

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