Ford 841 Carb: Sticking Float, or ???

Hi - Ford 841 gas with TSX 662 carb.

Runs great BUT will occasionally starve on gas. When it does, it idles low ok, but increase RPMs and she dies.

It's often like this at cold startup, but can then happen after a couple of hours running.

Best way to get it running is pound upside the carb with something heavy. Hit it hard a few or many times and eventually it clears up the problem and it's back to work.

Has a fairly new tank and shutoff valve and fuel line made from brake line. Glass gas filter seems ok...I think...

So...seems like it's a sticky float. I've rebuilt it twice, and opened it up numerous times, but can't see any reason for sticking. Measured float tang, it's ok, don't see float rubbing on the bowl anywhere.

So before I (gulp) buy a new carb, does anybody have any thoughts? Why the float might stick? Any way to verify it's the carb and not the delivery system? I'd hate to buy a new carb for big $$$ and have the same problem...

Thanks...
 
Does choking it hurt or help?? When was the last time you dumped the water and mud out of the air cleaner and fill it with fresh oil?? When you had the carb off could you flip it upside down and then right side up and hear the float moving?? Do you have a good blue/white spark the will jump a 1/4 inch gap or more
 
(quoted from post at 05:47:22 09/18/17) Does choking it hurt or help??
It always starts right up with nothing wrong, but dies either within moments, or keeps running until I increase the RPMs. No choke necessary when warm.

When was the last time you dumped the water and mud out of the air cleaner and fill it with fresh oil??
I keep it real clean.

When you had the carb off could you flip it upside down and then right side up and hear the float moving??
Yes, that's what baffles me. I can hear it move, doesn't stick or hang or rub...but when it's back on the tractor it acts up (not always, just periodically...)

Do you have a good blue/white spark the will jump a 1/4 inch gap or more
Yes, I've pretty much eliminated the electrical system as the culprit. There's full 12v to the points and coil at all times, the coil is solid (I had suspected it to be intermittent at one point, don't think so anymore...)

Also, this happens at all angles but it does seem more common when the tractor is pointing uphill...

I believe it to be the float but when inspected can't see any evidence. It could be some dirt or obstruction in the tank or shutoff valve or fuel line or filter, but don't see any, and things are pretty new and clean.

Any kind of test to pinpoint this to the float or some kind of obstruction along the fuel path?
 
I had a somewhat similar problem and the issue was a vacuum leak - in my case nuts securing the manifold to the head were a bit loose - worth checking in any case -
 
Two or three taps should jar float loose if it were sticking. Set a fire extinguisher within reach before draining any gas and catch gas as it drains. You can somewhat test wherther float is free. Remove plug to drain carb. If float stick's in raised position,flow will be small. If flow is good for more than 60 seconds,cover drain for 60 secounds with finger so that bowl refills. Remove finger and flow should be strong then taper off as bowl empty's. Repeat a few times to see if bowl is near empty when finger is removed from drain. A stoppage from tank to carb will act like stuck float. I know you said tank,fuel bowl and line are new but I would double check those before buying a new carb.
Make sure a large object isn't floating in tank and occasionally covering hole in valve. Drain tank,remove valve to clean and inspect passages. Clean the screen in glass bowl with carburetor cleaner. Either replace steel line or cut ends off, make sure line ends aren't restricted by rust then splice with fuel hose. The carb isn't supposed to have a filter on inlet nor is line supposed to have an in-line filter (only need the glass bowl),if it has either,remove them. Most in-line filters are desighned for pressureized fuel system. Instead of going through all the above,temporarily mount a clean small tank and run new line without filter to carb to see if problem go's away.
 

"can then happen after a couple of hours running. " eliminates sticking float or float needle valve. It is pretty much impossible for a float valve to stick while running. It is just coincidence that it will run OK after knocking on the side of the carb. What does it mean where you say screen in filter bowl "seems OK" ? have you removed the filter bowl and checked for something in the carb inlet?
 
Ah but have you in fact check that your spark is a good blue/white and jumps a 1/4 inch gap when the problem happens??? Just because you have a good spark at first does not mean it stays good and a weak spark can/will act like a carb problem
 
Good stuff, thank for the responses.

(quoted from post at 08:20:08 09/18/17) I had a somewhat similar problem and the issue was a vacuum leak - in my case nuts securing the manifold to the head were a bit loose - worth checking in any case -
Hadn't considered that. I rebuilt the engine a couple of years ago and come to think of it I haven't gone back and checked torques after the first month. Will inspect.

You can somewhat test wherther float is free. Remove plug to drain carb. If float stick's in raised position,flow will be small. If flow is good for more than 60 seconds,cover drain for 60 secounds with finger so that bowl refills. Remove finger and flow should be strong then taper off as bowl empty's. Repeat a few times to see if bowl is near empty when finger is removed from drain.
Have tried that, never definitive. Gas always flows strong. Makes me wonder if I'm freeing up a stuck float by draining the bowl...

Make sure a large object isn't floating in tank and occasionally covering hole in valve. Drain tank,remove valve to clean and inspect passages. Clean the screen in glass bowl with carburetor cleaner.
Have done that. Also checked flow from bottom of fuel line when problem occurs: very strong.

When I rebuilt everything I made a new fuel line from steel brake line. Recently saw a post here where some rubber line was added to remove stress from both ends...any thoughts on that? I used steel, not rubber, because the line runs so close to the engine. I'd wonder about vapor lock-type issues but this happens when cold too.

Instead of going through all the above,temporarily mount a clean small tank and run new line without filter to carb to see if problem go's away.
Yes, great suggestion. I'll strap a gas can with outlet at tank level and see if problem persists. That should provide near-definitive evidence.

It is pretty much impossible for a float valve to stick while running.
Why is that? The jiggling/movement would prevent it?

It is just coincidence that it will run OK after knocking on the side of the carb.
Sigh...could be...haven't been able to establish a 100%-certain pattern. Gotta do something standing out in a field in 100-degree weather...hitting the carb is as good as anything, no? ;)

Have you removed the filter bowl and checked for something in the carb inlet?
Yes, the system's been disassembled several times. Not that that guarantees perfection. Done this type of thing enough to know that when (or if) the problem is finally found it's often a head-slapper... :oops:

Ah but have you in fact check that your spark is a good blue/white and jumps a 1/4 inch gap when the problem happens??? Just because you have a good spark at first does not mean it stays good and a weak spark can/will act like a carb problem.
...and I know that the real solution is often one which I've previously dismissed as "no way" :roll: You're right, I should re-examine the electrical. I've got an LED on the dash that goes out if the 12v at the coil or points EVER drops...even for a millisecond...it's rock solid. And I've replaced the coil. But you're right, that doesn't test the actual spark. So that's now on the list again too.

Thanks for all the responses. I'm going to try the temporary tank first, see where that takes me. I'll repost when I get it fixed or (more likely) when I need more help...
 
Also:
A new needle and seat is cheaper than a whole carburetor
For sure. I've rebuilt the carb twice but as I recall the basic rebuild kit only provides a needle, not a seat. Any recommendations on a source for a decent rebuild-kit (or individual parts) that would include a seat?
 
I buy my carb kits from O'Reilly's auto parts Walker brand kit and they have to much stuff in them as in the kits cover more then one carb and have gaskets for more then one carb. I'm not 100% sure but I think the 778-505A kit covers that carb and the carbs on the 8N
 
(quoted from post at 22:10:40 09/18/17) I buy my carb kits from O'Reilly's auto parts Walker brand kit and they have to much stuff in them as in the kits cover more then one carb and have gaskets for more then one carb. I'm not 100% sure but I think the 778-505A kit covers that carb and the carbs on the 8N
Just checked the Walker catalog...for the TSX-662 they recommend 778-508 kit. It's got the needle seat. Unless you correct me on the kit info, I'll get one and see if it fixes things...
 
I have never seen a bad needle or seat preventing fuel flow, bad needle or seat fail's to stop flow and result's in flooding. I have seen trash lodge in seat stopping flow but that will occur with new seat as easily as an old one. As many times as this carb has been cleaned,new trash would have to be coming in with new fuel and would continue after needle and seat were replaced. The point I want make is,if you do replace needle and seat,carfuly check for trash in old seat when carb is taken apart. Why? So that you know to take measures to prevent more trash entering new seat.
 
(quoted from post at 10:46:16 09/19/17) I have never seen a bad needle or seat preventing fuel flow, bad needle or seat fail's to stop flow and result's in flooding. I have seen trash lodge in seat stopping flow but that will occur with new seat as easily as an old one. As many times as this carb has been cleaned,new trash would have to be coming in with new fuel and would continue after needle and seat were replaced. The point I want make is,if you do replace needle and seat,carfuly check for trash in old seat when carb is taken apart. Why? So that you know to take measures to prevent more trash entering new seat.

Chico is determined that it is the float needle. I don't know why he even came looking for advice.
 
Chico is determined that it is the float needle. I don't know why he even came looking for advice.
Whaaaaat?

I never said I was determined that it was the needle. In fact I rather doubt it is, based on the advice I've gotten.

I said all the advice was good advice, although I'd acted on some it previously.

These forums are great. I've greatly benefited from them. I came looking for advice and got good advice. Please don't put words in my mouth. Or troll me, if that's what this is...
 

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