8n only runs with full choke

[radrock]

Is this a tractor you have had for awhile and used to run good or one you just got? Altitude?

 

[Sawdustsmb]

did that carb have new screen filter elbow where the fuel line connects and is it clear?


getting a good flow to the carb when you turn the fuel on?

 

[Jerry/MT]

I have an 8n that was running a little rough and needed to have the choke out to run smooth. I thought it was a carb issue, so I bought a replacement and replaced it, still pretty much doing the same thing, that requires it to almost be full choked to run. Is this a gas mix issue? I have tried to alter the fuel mixture screws but not getting anything that seems to work, ideas? Could this be a points issue? I put new wires on as one had a small cut, but cant imagine that is doing anything.

There are at least two possibilities: a weak spark requiring a richer mixture(the usuual suspects are maladjusted, burned, dirty, corroded or oily points, high resisitance in the primary ignition circuit), or an air leak around the metering section of the carb (the usual culprits are worn throttle shaft, leaking carb to manifold gasket, cracked or rusted intake manifold, or a leaking manifold to cylinder head gasket).

Which distributor do you have, front mount or side mount?

 

[Soundguy]

needs choke to run:

plugged fuel delivery ( rank to carb and all inbetween must be checked )

weak spark

vacume leak.

choke enriches a mix.

rich mixes fire easier ( weak spark )

vacume leak leans a mix.. choke re-enriches it.

post back what ya find.

 

[fibrostic]

OK so today I installed all new fuel sediment trap with both screens, and a new elbow with screen going into carb. Fuel flow from line going into carb is solid stream, the flow coming out the drain on the carb is more than a trickle but not a solid stream.

Currently if you let it sit for a couple minutes you can keep it going for about a minute, then it starts and dies after a couple seconds. Thus my thought is something is clogging the fuel getting into the carb. Could this be a needle valve issue? If so, what can i do? are there adjustments on it?

*Update*
I think i mean float valve and not needle valve.

*Update 2*
So i pulled the carb off again, tore it apart and really checked the action on the float and the float valve. Noticed that it seemed to be sticking a bit...maybe..., so i took it all apart flushed everything with cleaner and polished the little float needle and the seat. put it back together and it ran much better, though still running weak. I turned the gas valve all the way open and it runs like a champ (note the little circle that acts as the handle on the sediment bulb came off when i opened it all the way up, and of course i lost the screw) Now the question is, problem fixed?

 

[Soundguy]

likely the fuel flow issue is fixed.

the old fuel taps, had 2 settings.. open and open with reserve. it was 2 different heights of pipe in the fuel inlet.. nowadays there is only 1, so just open the valve all the way. plus some valves have the lil orifices not drilled perfectly, so anything less than full open can impede flow.

if it is a bras needle and not a viton needle for the float, then yeap.. a lil polish with rubbig compound or toothpaste ont he needle, and a toothpick into the seat helps. also making sure adjusted to 1/4" ( i use a drill bit stem as a gauge ) and making sur ethe flaot does not hang up, nor has a pinhole in it.

if it seems weak, enrich the main needle 1/8 a turn at a time and gun the hand throttle .

lean fuel setting will make a slow rise or stumble and rise of the rpm.

correct setting provides a good acceleration of rpm, and no heavy smoke out the exhaust, though a puff is ok.

rich meaks sooty black smoke out the ehaust upon throttle up, and may gurgle an semll rich and stumble a bit int he top end as if you were choking it ..

soundguy

 

[fibrostic]

So was running the 8n last night, drove all over the property without issue in 1st to 4th gear. Was extremly happy that it sounded bettter than any other time i had owned it. Went down to the barn and hooked it up to a spreader (ground driven). About 2 minutes into the field it started to bog down and started to learch, die and rev, die and rev, etc. Had to limp back to the barn and switch tractors. This is getting old fast.

 

[E/S]

Did you check the vent on the fuel cap ?

E/S

 

[murphy1244]

Sounds like a intake leak might be the culprit here.

There you go,, That sucker is sucking air some where.

 

[E/S]

There you go,, That sucker is sucking air some where.

Or vacuum locking the tank.

E/S