Unusual symptoms, needle valve restriction?

[braol]

Farmall H did this the other day: I was discing a new hayfield to prep it for planting. We used the tractor for several hours without a hiccup...and then suddenly it would sputter while pulling the disc when making right-hand turns but idled just fine. It also would run at full throttle just fine as well. We were done anyways and so i disconnected the implement and went to eat lunch. When I came out later to put the tractor away, it would start, run fine, and then die (like someone just pulled the plug). I got it to the point that when it started to die I could pull the choke out a little bit to keep it running, it would catch, run for a bit, start to stumble, repeat.

At this point, I pulled the carb, cleaned the fuel bowl, looked in the tank, split the carb, inserted my cleaning wire into all different places, carb cleaner, etc... Checked plugs, the whole 9 yards. The next phase was that it would idle fine (not die all the time) but still sputter when making right hand turns and it would pull the disc straight ok for a bit...stumble for a bit...run ok, etc...and on and on. Last night it would almost die when making turns while pulling a drag through very loose soil (left AND right) but still seemed to run ok at full throttle when just standing there. I tried enrichening the mixture a few turns with the load screw, it made it a little bit better, but didn't fix the issue. Plus opening the screw three turns when it was adjusted fine for 2 years isn't right. I don't let the tractor sit all winter and I use ethanol free fuel and almost always close the fuel valve when parking the tractor.

What gives? It there something slightly clogging the needle seat? Why only under load when making turns (mostly)? If the tractor runs pretty well at full throttle (meaning that the needle/float/seat is open providing fuel) why would pulling a steady load and then turning kill it? It's not like the needle is sticking closed. Is it possible that there is dirt clogging the passage from the load screw into the carb somewhere?

Any help or anecdotes would be MOST welcome!

This post was edited by braol on 04/16/2023 at 11:39 am.

 

[rustyfarmall]

Something in the tank maybe? The object floats around and partially covers the fuel inlet when the gasoline sloshes while making right hand turns.

 

[used red MN]

Hopefully, you are aware that the fitting that the fuel
line screws into to connect to the carb has a screen on
it, see link. Is it clean? If that is good what is the gas
flow like out of the carb drain plug? Does it flow
continuously a fair stream for at least 15 - 20 seconds?
It should not slow down to a dribble. Since you may be
just on the verge of enough gas flow you should
probably do an actual measured flow test. Have a pint
measure ready and a timer. Open the drain and let it
flow for 10 seconds, this drains out the fuel stored in
the carb bowl you cannot measure that for an accurate
test. After the 10 seconds start catching the gas in the
pint and let it flow 3 minutes. If it at least fills that pint
measure you should be good. That is 2.5 gallons per
hour. Per the engine testing the consumption is 2.4
GPM under full load. It may use a bit more than that
because it very likely has been overhauled with over
bore pistons. Just FYI if you have an inline fuel filter
added to it some of those do not allow enough flow on
gravity flow systems. If that seems to be good next
time it acts up feel the coil and see if it is hot, by that I
mean not being able to hold your hand on it hot. If this
is the case it is probably bad. What did the plugs look
like that you said fouled in your other post?
YT H carb fuel fitting and strainer

 

[braol]

Back when I had the no-start issue a few years ago, the plugs were black and oily. (It will need new sleeves and/or valve guides at some point.) I pull wires to check for non-firing plugs once a week and pull plugs when they start to foul. I checked the plugs when I had the issue this time.

I have great flow out the fuel line from the tank. I made sure to pull the line, run wire through the line, blast with carb cleaner, empty the sediment bowl, etc...

It is also a brand new carb last spring (2022) and new intake manifold. (No, I did not pull the strainer fitting...it slipped my mind.


This post was edited by braol on 04/16/2023 at 12:45 pm.

 

[504]

I bought a nice 504 Farmall that had been in a garage
for a few years. I had moved it lots of times always
ran good. I bought it from the owner, and I decided to
just run it home instead of hauling it. 10 miles later
I just made it into a driveway before it quits.I
cleaned the carb,cleaned the sediment bowl. It ran 1/4
mile and quit again. I finally made it home after
three days of cleaning everything along side of the
hwy over and over. 6 miles if you are counting. All it
was, was fine rust in the tank,slow speed it would
run,high speed it ran out of gas. I pulled the tank
cleaned it,took an old mig gun liner and rodded out
the fuel line and added a 3/8 inline filter and kept
it around for 10 years before I sold it.

 

[Janicholson]

An ignition wire that is internally broken (or a bad switch (really)) can do that. The wire can also be shorting on something! turns and vibration make it fail. Jim

 

[13fx]

So the key here is you say that
it dies like someone just pulled
the plug. This is going to be an
ignition system problem. You are
not getting good spark all the
time. Inspect all the wires for
any cracking of the insulation,
check the boots. If you can't
find anything visual try
swapping out plug and coil
wires.

 

[rustyfarmall]

You have all missed the point that the tractor exhibits the problem ONLY while making turns.

 

[13fx]

Only right hand turns, the
ignition system is on the right
hand side, when turning right
the wires will slightly sway
towards the block allowing a
wire with cracked insulation to
arc out causing a miss fire.
When turning left there isn't
any problems for him do to the
wires slightly swaying away from
the block. If it was a fuel
problem it wouldn't matter what
way you turned it would act up.
If this was a coil system I
would have him first check the
wire from the coil kill switch
to the coil for rubbing, but as
it's a magneto system we can
rule that one out.

 

[rustyfarmall]

(quoted from post at 11:09:33 04/17/23) Only right hand turns, the
ignition system is on the right
hand side, when turning right
the wires will slightly sway
towards the block allowing a
wire with cracked insulation to
arc out causing a miss fire.
When turning left there isn't
any problems for him do to the
wires slightly swaying away from
the block. If it was a fuel
problem it wouldn't matter what
way you turned it would act up.
If this was a coil system I
would have him first check the
wire from the coil kill switch
to the coil for rubbing, but as
it's a magneto system we can
rule that one out.

Provided the spark plug wires are of the correct length, there is no way that they could sway enough to ground themselves against the engine block.

 

[Janicholson]

A mag has a wire going to the kill switch. It can ground!! Internal wiring in the mag and the pass through are also issues to check. Jim

 

[braol]

PROBLEM SOLVED: It turns out that the graphite packing that surrounds the load screw (#24703DA...number 19 in the Case/IH diagram, only $4) was deteriorating and pieces of it had broken off and was plugging the main jet. Why it was worse when turning, I believe, was because it put the tractor under more load and it just wasn't flowing enough fuel to keep up. It now runs flawlessly (whew!). The new one is on the way but i am making due with how it is until then.

I never would have found the problem if I hadn't finally removed the drain valve. Only then could I visualize the the parts of the packing lodged between the needle valve and the back of the drain passage. No amount of draining or flushing would have gotten rid of it on it's own. Oh, and get this: On my old carb (which always dripped and had it's own problems) had nothing but particles where the old packing had been. I've ordered two of them from Case so now I will have a good spare carb avail. Thanks to all who posted. Man, am I glad it wasn't ignition. Enough was enough.

 

[rustyfarmall]

I have rebuilt MANY of those carburetors, and replaced that packing in every one of them. Removing the old packing was always a real challenge. Had to use a small, pointed pick and basically dig the old packing out, one tiny crumb at a time. Never encountered one that was coming apart while still in the carburetor.

 

[braol]

I also encountered an additional problem just a month ago when the tractor started acting up again and SOLVED it. There was a round, plasticky-ish item in the bottom of the tank that I was able to see with a mirror and a strong flashlight. I was able to fish it out with a yardstick and a long piece of stiff wire working in tandem. Just another thing people can look out for when investigating fuel problems...

 

[BarnyardEngineering]

(quoted from post at 10:15:37 04/21/23)Why it was worse when turning, I believe, was because it put the tractor under more load and it just wasn't flowing enough fuel to keep up.

That's exactly what was going on.

Same reason it would run smooth at full throttle with no load. You can't see it happen on an H because the governor linkage is in a tube but if you have another smaller tractor like a Cub, A, B or C, you can watch the carb linkage when you pin the throttle to full. The governor will shove the butterfly open momentarily, but return it back to almost idle as soon as the tractor revs up. Yet, the tractor will be running "full throttle!" That's because it takes very little fuel and air to make the tractor run at "full throttle" with no load.