won't idle

[SteveS]

8N side mount won't idle except with choke. New points, wires, spark plugs,cap and rotor. Carb rebuilt once and taken apart again to check for blockage-- none that I can find. Checked for intake leaks with propane. Interesting part is it ran about the same way when I brought it home but it wouldn't start very good.It must be a simple problem but I am not seeing it. Before I but the carb back on, any ideas?

 

[Dan in CO]

I am dealing with exactly the same issue. I recently rebuilt my old carburetor and couldn’t get it to run right, so I splurged & bought a new one, the black one sold at many on-line sites. I put it on and the tractor would run fine at high idle and above, but needs ½ choke to idle. After a lot of work (on and off the tractor many times) I discovered that there are cracks in both the top and bottom casting. It is so bad that it leaks gas from the bowl and from above the float valve into the throat and then out of the vent. No amount of spraying with WD-40, carb cleaner or propane caused the air leak to show itself because the air leak was from the throat to the idle jet. That air leak also shows up as a gas leak when the tractor sits for more than 30 minutes, and it doesn’t matter if I run the bowl dry before I shut it off. This probably doesn’t help your situation, but you might want to look for cracks.

 

[Jerry/MT]

Your idle adjustment screw adjusts the idle airflow so it works backwards from the typical jet. That is, when you screw the idle screw in, it enriches the mixture. So make sure that you have the adjustment correct.
There maybe two different problems causing your difficulty; air leakage around the carb metering section or a weak spark.
Tackle the spark issue first. Pull the center wire from the distributor cap and hold it near a good ground. Try a start. You should have a FAT, BLUISH-WHITE SPARK. If its reddish, yellowish or orangey, you have a problem with the primary ignition circuit. The points are not set correctly, are burnt or corroded, bad connections, bad key switch, bad coil, etc. Your weak spark will ignite a rich mixture but not a lean one so the engine will run with partial choking.

The other issue that could cause this problem is a leakage of air around the carb metering system. This will cause a lean condition that will be alleviated by partial choking. The leak could be around a worn throttle shaft, at the carb to intake manifold connect flange or at the intake manifold to block or cylinder head connection. To check for this problem, CAREFULLY spray starter fluid around the above mentioned joints and if you hear the engine pick up speed when you spray a particular joint, you"ve found the problem area.

hope this helps.

 

[souNdguy]

Needs choke to run:

Obstructed fuel flow.

Weak sparks.

Vacume leak.


Soundguy

 

[jack in walllace]

Just had a similar problem w a 47- 2n. would not idle with out 1/4 choke, progressivly got worse. took the distrbutor out, found the points closed up to almost zero. regapped, runs fine now.

 

[SteveS]

new sump. new line. new screen in carb fitting. I'll go over the vac leak procedure again.

 

[souNdguy]

Fuel obstruction does cover all the way thru the idle/main jet circuits.. so don't overlook them.

soundguy

 

[SteveS]

Changed float setting. now idles with idle screw almost all the way in--maybe set float again-maybe not. Thank you all for the help.