Can you tell what is wrong with my Ford 8N's engine?

[macecase]

If you listen to this engine in this video, the engine sputters and almost dies... then, revs back up.

You will notice that the engine is never stable and a half throttle it almost dies and then it races. What could be wrong with it? It never dies all together.... just does this non-stop.

 

[George2615]

Sounds like a fuel starving problem to me. Could be bad fuel, water in fuel, sediment in fuel line, blockage in fuel line, carb needs rebuild, float problem in carb.
Forgot to mention air filter could be plugged too.

 

[Soundguy]

I agree, could be fuel starved, then gov guns it to keep rpms up, over revs and goes back down, starving again.

If it is not a fuel issue, a adjusted gov spring/rod can do this making it osscilate up and down in revs hunting.

 

[Looking4new]

What does it do when you loosen the fuel cap?

 

[macecase]

I agree, could be fuel starved, then gov guns it to keep rpms up, over revs and goes back down, starving again.

If it is not a fuel issue, a adjusted gov spring/rod can do this making it osscilate up and down in revs hunting.

I replaced the carb today with one I had on the shelf which was recently rebuilt....... Same problem although not quite as bad sounding. However, when you go to use the tractor it bogs down and dies...

I am wondering if it is more timing.... That is my guess considering air and fuel should be good at this point... So, spark... or something with the distributor?

 

[macecase]

What does it do when you loosen the fuel cap?

Didn't try... But, I have one of those gas caps that has the fuel float in it. It has hole drilled in it to relieve pressure. Should I take that out (completely remove the gas cap) and try it?

 

[Soundguy]

Have you checked the governor. Does it fight you if you manually open the carb butterfly flapper, while throttle is set at idle?

On the issue of timing, is your adv mech moving freely?

 

[Looking4new]

Didn't try... But, I have one of those gas caps that has the fuel float in it. It has hole drilled in it to relieve pressure. Should I take that out (completely remove the gas cap) and try it?

I wouldn't remove the gas cap completely.
If you have a set of tip cleaners for oxy/acetylene torches, try cleaning the vent holes. IF not then a very small drill bit will do the same job.

 

[skylarkguy]

I'm not sure you have eliminated all the fuel starving options. The carb now has been replaced. But you have a tank with crud in it fuel bowl and maybe filters that limit fuel flow.
My naa had similar symptoms and after cleaning out the tank no more issues.

 

[ironnut]

Is the exhaust sooty? Does it smell of unburnt gas? I would lean towards carburetor problems, as it sounds like an overly rich mixture. If the carburetor has an adjustment for the main jet I would try to lean the mixture ( turn the adjustment screw clockwise). Typical starting point is to turn the main jet adjustment knob in until it seats, don't force it, and then back it out 1 1/2 turns. The engine should start and run reasonably well and then you can fine tune it as it warms up. If you can't get it to run smoothly then the carburetor needs cleaning or it was not assembled correctly. I would also check the ignition system to make sure you are getting good spark to each of the cylinders though the way it is running suggest fuel mixture problems. I would expect the spark plugs to be black and sooty.

gordon