8n only runs with full choke

[Soundguy]

easy to test the tank....

 

[LD1]

Any feedback yet on what others have posted???

All some good pointers:thumbsup:

1. Check intake for leak. (spraying carbcleaner around manifold)
2. Check gas tank vent.
3. Check screens.


The 8n has 3 fuel filter screens. Most people dont check ALL 3.

There is one INSIDE the tank. On the tube that goes up into the tank from the sediment bowl.

There is another in the sediment bowl housing.

And then the one in the elbow where the fuel line hooks into the carb.

We need a little more feedback (answers) to some of these checks so we can help you get here purring like a kitten again.

 

[Treemonkey1000]

Surprised no one has told him to put Seafoam in it yet. Tank vent wouldn't have prevented it from running bad at first then cleaning out his carb and it ran good for so long. I like the leaky gasket or fuel connection theory myself.. I am guessing there is not a clogged air filter either?

 

[fibrostic]

Sorry been dealing with other issues at the farm. I havent gotten around to testing the air leaks, though it could be the issue. Checking the tank, would that just entail pulling the cap off when it is under a load. I guess i never really looked at the cap to see how it is vented, can they go bad? I can pull the tube for the air filter and give that a shot, but dont think that is the issue.

Yes i checked all the screens, and since they were all new when i installed them (last week), they are pretty clean.

I have a 3 day weekend coming up so i should have time to test some of the other suggestions. Thanks for all the help on this.

 

[ultrarunner]

Not an 8N... but similar.

Three most common cause for the symptom describe on a Model A Ford...

Restricted Fuel Flow... Sediment, Tank Vent or Wrong Filter.

Sediment: Had a rash of problems with some of the older, unrestored cars with the new California Fuel which would loosen decades of gum and varnish all the way to the carb.

Vent: The vent hole is relatively small and easily obstructed...

Filter: Most of today's filters are not designed for gravity systems... they depend on the fuel pump pressure to work... I don't know if the 8N has a pump? I've found motorcycle type filters work well because they are designed for gravity flow fuel systems.

 

[g0rd0]

with gas engines it is fuel, air, and spark. if all 3 are there in the right amount :thumbsup:.
Since you have cleaned out your tank and lines the fuel should be no problem (did your new carb come with setup instructions?) if so double check to be sure. After that all there is to check is spark, are the wires in good kit? Is the coil delivering the right voltage, is there a crack in the distributor cap, are the points set correctly? If you have a vacuum advance on the system is the vacuum line clear?
Now if all of this checks out is the timming set correctly?
Good luck, Hummm I like deisel.

 

[Egon]

Go back and twiddle with the hi/low jets. If that does not work look at float and needle seat setting.

 

[Soundguy]

carb twiddling is the worst thing you can do BEFORE figuring out the problem.

A incorrrect idle air jet setting won't cause a no start.

a lean mainjet can be checked by tugging choke.

8n ag engine had no fuel pump.. industrials could have a mechanical one.

fuel tank has the vent.. not the cap.. and is easilly plugged.

soundguy

 

[Charolais]

Had a Wisconsin air cooled irrigation pump motor that after years of running had to use the choke to make it run correct. That worked for a while till the choke was being used at full choke position and the engine wouldn't run correct. The problem with that was burned valves. As the valves got worse had to keep adding more choke. Pulled the engine down and put in new valves and seated them and the problem went away. We went through the same process as you have with carb. settings and fuel flow. Just happened to be the valves on this engine.

 

[ultrarunner]

Had a Wisconsin air cooled irrigation pump motor that after years of running had to use the choke to make it run correct. That worked for a while till the choke was being used at full choke position and the engine wouldn't run correct. The problem with that was burned valves. As the valves got worse had to keep adding more choke. Pulled the engine down and put in new valves and seated them and the problem went away. We went through the same process as you have with carb. settings and fuel flow. Just happened to be the valves on this engine.

Good point, especially if the problem came about gradually...

Whenever I bring home something with a gas motor... the first thing I do is a compression test and record the data...