Help with fuel problem

[jorswift]

I know there are a series of tests to try, but wanted to see if anyone has had the same problem before I dig in... Problem is...

I replaced the fuel sediment bowl as it was kind of leaking and the gasket was in bad shape. I replaced the gasket with a cork homemade gasket. I believe I got all the air out, but now my problems start. It starts and idles fine, but when I open up the throttle it acts as if it is starved for fuel. I pull the choke out and it seems to help run normal. It also does it with a load on the back. Would air in the line do this? I am hoping it is a clogged line. Thanks.

 

[Bruce (VA)]

Pulling out the choke gives you a richer mixture. So, you could have either a fuel or spark problem.

A carb out of adjustment will also cause this problem; set the main jet at 1-1/2 turns out & leave it alone.

A dirty carb can cause the problem as well; start by cleaning the fuel screens. (see tips 45 & 56)

Dirty/old gas, or water in the gas can cause this problem.

Restricted fuel flow can cause this problem; remove the bolt at the bottom of the carb & check for flow. The flow should fill a pint jar in under 2 minutes.

On my 1950 frontmount, needing choke to run is the first sign that the points need adjusting/replacing.

A vacuum leak can do the same thing. Get a hand propane torch and carefully spray it (unlit of course) around the intake manifold at the carb to manifold interface & the manifold to block gasket of the tractor while it is running. Or, you can use carb cleaner or WD40. If it speeds up, you found the leak. Sometimes (rarely) manifolds crack or get rust holes.

Lastly, when all else fails, you could have an air leak around the carb metering section. The likely suspects are leaky throttle shaft seals and/or a worn throttle shaft. Or, just a real dirty carb w/ clogged passages.

Bottom line: Probably 90% of "needs choke to run" problems are fuel related, but do not rule out ignition problems, contrary to what others may tell you. I?ve had that very same problem before w/ a rebuilt carb, fresh fuel & good flow & a tight manifold.......and it was a spark problem. But, that was unusual. Just check the likely fuel problems first.

Please be sure to post back & let us know what the fix was. We all learn something if you tell us what worked!
75 Tips

 

[HCooke]

" I believe I got all the air out, "

Not your problem and not necessary to remove the air. Air in the bowl when you replace the gasket and bowl is good - it means no leaks.

Like Bruce says you probably have a spark problem. When was the last time you replaced or cleaned and gapped the points?

 

[jorswift]

(quoted from post at 07:33:48 06/01/17) " I believe I got all the air out, "

Not your problem and not necessary to remove the air. Air in the bowl when you replace the gasket and bowl is good - it means no leaks.

Like Bruce says you probably have a spark problem. When was the last time you replaced or cleaned and gapped the points?

Points are relatively new. It is weird because the tractor ran fine right before. I jacked up the front, changed oil, oil pan gasket and fuel bowl gasket. Ever since, I have had these issues. I did let the tractor run with the fuel turned off to use all the fuel left in the carb before I changed the gasket.

 

[Bruce (VA)]

And that probably filled the carb with crap.

 

[HCooke]

If you are confident that the points are not corroded and that the gap is correct and you have a good spark that will jump a 1/4" air gap,
then a carb overhaul may help.

 

[Royse]

Welcome to the forum!
I rebuild these carbs for folks. ~75-100 per year.
I was testing one this week and it had similar issues.
Since it was already suspect, I took it apart and re-cleaned it.
Same issue, so I put my own carb back on. Yep, same issue.
I cleaned and re-gapped the points and both carbs are fine.

So, I would check spark. It's free and easy.
Cleaning and re-gapping points is also free.
I know you said your points are fairly new, but if your points
have a plastic rubbing block, I've had them wear off in a few hours.

If it does turn out to be a carb issue, let me know.
I'd be glad to help you rebuild it via email or phone.
Or I could do it for you if you prefer. That's not free though.

 

[jorswift]

Well, you all have being doing this a lot longer than myself... But I think the tractor gremlins have me! I let the tractor sit overnight in the field I was working in and went back the next day to rework the field. Low and behold the tractor ran fine without a hiccup! I have no idea?!?!

But I know I am do for a carb rebuild for sure. I may make that my next winters project!

 

[Nutty]

(quoted from post at 05:54:29 06/01/17) I know there are a series of tests to try, but wanted to see if anyone has had the same problem before I dig in... Problem is...

I replaced the fuel sediment bowl as it was kind of leaking and the gasket was in bad shape. I replaced the gasket with a cork homemade gasket. I believe I got all the air out, but now my problems start. It starts and idles fine, but when I open up the throttle it acts as if it is starved for fuel. I pull the choke out and it seems to help run normal. It also does it with a load on the back. Would air in the line do this? I am hoping it is a clogged line. Thanks.

i had this problem too, but first, take the plug out of the bottom of the carb and make sure that about a pint of gas flows out in 3-4 min. If thats fine, it's probably spark related. What i did wasI drained the gas out of the tank, took the sediment bowl off, and found some rust covering the sediment bowl intake. This was my problem, but you might have a plugged fuel line, or something in the carb broke. Just my 2 cents.
Nutty

 

[HFJ]

(quoted from post at 15:41:45 06/02/17) Well, you all have being doing this a lot longer than myself... But I think the tractor gremlins have me! I let the tractor sit overnight in the field I was working in and went back the next day to rework the field. Low and behold the tractor ran fine without a hiccup! I have no idea?!?!

But I know I am do for a carb rebuild for sure. I may make that my next winters project!

u didn't happen to pour more gas in when u came back out to it, did u?

 

[showcrop]

(quoted from post at 11:41:45 06/02/17) Well, you all have being doing this a lot longer than myself... But I think the tractor gremlins have me! I let the tractor sit overnight in the field I was working in and went back the next day to rework the field. Low and behold the tractor ran fine without a hiccup! I have no idea?!?!

But I know I am do for a carb rebuild for sure. I may make that my next winters project!

How do you know that the carb is due for a rebuild? I have never heard of a service interval for that.