Fuel problem 8N

I am new on the forum, but I have read some of the past posts.
I have a 1952 8N, the problem is it will run for about 30 min or so, then sputters/spits until it quits running. It will fire up again, then die. If let set for 30 min or better, it will run longer. It has been converted to 12v. has new coil, points, rotor, spark plugs, fuel bowl, etc. I tried an experiment and used a translucent fuel hose and noticed that when it starts acting up, the fuel line had bubbles that got bigger and bigger until no fuel got through. Pulled the tank off 3 times and cleaned best I could (all kinds of stuff including dragonfly wings!). Any ideas? Last year the tractor ran perfectly fine.

Did you clean the fuel tank vent? That is the bulge on the top of the tank. Has a pin hole that gets plugged. If not, you can buy a vented fuel cap that years ago was originally traded free by dealers because of clogged vents. Now you have to buy them.

Get a can & put it under the carb. Remove the bolt in the bottom of the carb; as long as the fuel is turned on, you should see gas flowing out of the carb. It should fill a pint jar in less than 2 minutes. If it?s a dribble, or runs for 5 seconds & stops, or none at all, you have solved half the problem: it?s fuel related. If gas flows well out of the carb & only stops when you turn it off at the sediment bowl, chances are very good it?s not a fuel problem.If it does not have gas coming out of the carb at a steady stream w/ the bolt out for at least 30 seconds, you have a fuel problem. First, remove the gas cap. Your vent could be clogged & it vacuum locked. If that doesn?t work, tap the carb bowl w/ a hammer handle in case the float is sticking closed. (don?t whack it w/ the head of the hammer; you can crack the bowl). If you still don?t see gas flowing, the N has three fuel screens; one in the brass elbow, one in the top of the sediment bowl & one on the stem of the sediment bowl in the gas tank. (see tip # 45) Check the screen in the elbow (see tip # 56) & the screen in the top of the sediment bowl. (don?t worry about the one in the tank) Both probably need to be cleaned. If you have the fuel knob turned on all the way, & 1 gallon or less in the tank, it may be trying to feed off of the reserve inlet which is probably clogged. Only open it 2 full turns. Put at least 2 gallons in the tank. (and do not forget to turn the gas off; see tip # 9)
75 Tips

Yes, cleaned the vent hole in the tank. The gas cap (worked last season) I actually drilled a off-set vent hole as an experiment...no change.

Actually removed, cleaned and replaced the fuel bowl and components. When I experimented with the translucent fuel hose I had removed the fuel bowl (and filters) for the test.
I will try the carburetor check you suggest. May take a few days, everything is under ice right now!

(quoted from post at 11:10:40 01/16/17) Actually removed, cleaned and replaced the fuel bowl and components. When I experimented with the translucent fuel hose I had removed the fuel bowl (and filters) for the test.
I will try the carburetor check you suggest. May take a few days, everything is under ice right now!

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If all else fails , You can install a 1/8" npt hose barb on the bottom drain and run the translucent hose above the carb to see your fuel level during operation . I would zip tie it to the steel fuel line above the carb and tighten the zip tie enough to hold it but still leave the hose open for air to pass through .

Once you rule out fuel as the problem, then move on to spark.

As soon as it stops running, not 5 minutes later, see if the spark will jump a 1/4" gap. (see tip #13)
75 Tips

[b:71d742388f]"When I experimented with the translucent fuel hose I had removed the fuel bowl (and filters) for the test."[/b:71d742388f]

i'm confused. what did u have the translucent fuel line attached to at the tank end? did u install a barbed fitting in place of the sediment bowl assembly?

Yes, you are correct!

in which case, i can only think of one way air bubbles could get in the fuel line - and that's if u were nearly out of gas.

It was vented, even removing the cap. And I had over 1/2 tank. Has to be something else....I will keep searching.

where else do u suppose air bubbles got into the line from? are u sure u had the properly sized fitting and it was tightened properly, and the line has no holes in it? there's nothing in the tank that would allow your fitting to pull air thru half a tank of gas.