Up draft carb issues.

[Ron Bailey]

Tractor running like crap under load after I e done all this. Replaced all ignition components and put a new up draft carb on.
Ive went into the carb a few times to make sure no keys was clogged, tried doing a little carb main jet adjustments. But my feeling are its something with the carb, its actually icing up
Any ideas ?

 

[Ron Bailey]

I meant jets, not keys. Is there not a way to edit ??

 

[Masseyharrisnut]

Frosting up like that is common. Quite a few of my Massey Harris tractors do that on a regular basis.

 

[Dieseltech]

That's common in cool/damp weather, and why intake manifold heat is needed to overcome the frosting. A preheat stove around the muffler to draw warm air int air cleaner inlet will help too. The old Massey-Harris 44 with it's long intake will frost over even worse than the pic shows.

 

[used red MN]

Is that gauge showing fuel pressure? Does it hold pressure under load when running bad?
Edit: There is no edit feature in Classic View, you have to log in on Modern, then the ..Edit.. button shows in your post.

This post was edited by used red MN on 12/04/2023 at 08:22 am.

 

[Ron Bailey]

Yes I put the gauge on so I could see if it was loosing pressure. But it stays steady.

 

[Ron Bailey]

Oh. Ok. I have never seen that. Thought maybe it might be a symptom of my problem.
Thanks

 

[Ron Bailey]

Ok. Thanks. I have never seen it before. Lol. My first updraft.

 

[M-MAN]

What are you working on? Looks like you bought an aftermarket zenith? What was the original?

Try adjusting the load needle. At full throttle ease it in and out until it's smooth. Then back it out until it barely stumbles. Then ease it in until it evens out and stop.

 

[wore out]

Even with intake manifold preheat they can ice up a little!

 

[Ron Bailey]

Yea its an after market carb. It had the original carb on it. The fuel cut off on the carb broke and was no longer available So new carb it is. When I first install it and all the new ignition parts it ran great. Then it started popping and cutting out. Ive went back through everything checking. Maybe something simple, like I got a bad plug and it only misses under load. Thats about the only think I havent checked, maybe another set of plugs would do the trick.
Just running out of ideas.

 

[Ron Bailey]

Lol. Wow. Thats crazy!! Thanks for the picture!!!!

 

[JD Dave]

We don't know what model tractor you are working on. I'm not a fan of aftermarket carbs. Sometimes they cause more problems than one had in the first place. Need more specific information to comment further.

 

[Ron Bailey]

I got this carb from YT. Seams well made.
I had no choice.
1980 350B crawler

 

[RobCons]

I see you replaced all the ignition components but verify spark, voltage, and wiring condition. I recently went though similar conditions and discovered the negative wire from my distributor to the coil was broken. Tractor would run for various amounts of time great then sputter or stop depending on how the wire vibrated.

 

[Ron Bailey]

10-4. Thanks for the info. Got to be something Im just over
looking!! Ive regapped the new points, a new ground wire, new
dist cap, new plug wires and new plugs. New carb. Lol. Im
pretty good with mechanics Ill just have to keep digging

 

[rustred]

perfectly normal on any up draft carb. its called the venturi effect. have u ever felt the carb in the summer time, it gets pretty cool also but not like that in the cold weather. they usually just get wet. the air goes through the venturi which speeds it up causing a vacuum to suck the fuel. this speeded up air cause this.