IH 354 carb issue

[Ogrumpyone]

Good morning all. I'm working on an IH 354 gas with the British Zenith downdraft carb. I have rebuilt this several times and am stumped. Hoping you all can help. I am pouring fuel from the emulsion tube as soon as I crack the throttle blades. Fuel fouling the plugs instantly. I have gone thru this carb and played with float levels. It will do this even with the fuel supply disconnected. Only pours fuel when cranking and throttle is not completely closed. I can't seem to find an issue, everything had been cleaned and blown dry. I don't see any visible cracks. Gaskets are good. I'm sure I'm missing something simple. Thank you!!!!

 

[Janicholson]

Making sure the needle and seat are holding is critical. with the carb off the tractor, and the fuel bowl off, put light air pressure (5 or 6 psi max) into the carb fuel
intake fitting then see if the sir flow stops when you turn it upside down, or gently lift the float. If it flows, it is in need. Jim

 

[used red MN]

Hello Ogrumpyone welcome to YT! Never worked on
one of them carbs they look to be a little more complex
then needed for an old tractor, probably make anybody
grumpy. What is the condition of the tractor? Are you
trying to get it running after it had been setting unused
for a time. A crudded up fuel system from setting with
bad gas in it is not an easy problem to overcome. It
looks like the screen in the fuel pump number 5 in the
link is the only filtration in the system. Did you
look at it is it intact? If dirty fuel is a problem with your
machine you may just have to bite the bullet and cut
the fuel line between the fuel pump and the carb and
install an in-line fuel filter. I am guessing as Jim
suspects that your float needle valve is simply not
shutting off because of debris in it and the fuel level
gets to high in the carb. Since it will not just drip out as
it would in an updraft carb you may have to loosen the
carb and pry it up a bit and slide a screwdriver under it
to hold it up a bit. Pull the coil wire and crank the
engine 5 seconds or so. Now watch the bottom of the
carb through the gap, I bet you soon see gas dripping
down from the carb because the float needle is not
sealing. I would add the filter in down after the pump
so the hoses for it are exposed to less heat. You will
also have to make sure the inside of the fuel line going
up to the carb is clean inside so nothing is coming
loose to get in the float needle, rod it out with a wire,
then a shot of carb cleaner and finish with a blast of
compressed air.
CNHI IH 354 parts catalog

 

[Ogrumpyone]

. Thank you for getting back to me. I have checked the needle and seat. The issue is I can disconnect the fuel line so it's just running off what's in the bowl and it still pours fuel during cranking if the throttle is open. As for condition, it is or was a running functioning tractor. The dizzy was getting really bad but my friend said it acted like it ran out of gas. It just died. The plugs were soaked but I figured at that point it was due to him cranking on it with bad or no spark. I replaced the dizzy and know the points and static timing is good. I had it idling for a few seconds last night but then fuel fouls the plugs within seconds. They are soaked.

 

[Fritz Maurer]

Did it run before you took the carb apart, or did it start
this fuel dumping on its own?

 

[Janicholson]

Has the air cleaner been checked for restriction? a bad intake hose, or frozen water in the oilbath system can make this happen? Jim

 

[used red MN]

If the fuel level is to high when you disconnect the line
it will flood over to much fuel when you change the
static pressure in the carb throat by opening the
throttle plate. Doing what I suggested should let you
see if the float needle is leaking by. If debris is getting
in the float needle it will continue to not be able to
seal. At least check to make sure that screen is intact
in the fuel pump. After you get that back together
before connecting it back to the carb crank it over and
flush out the line to the carb of any debris that may
have been dislodged. The manual I have says the float
is not adjustable so maybe you have something
tweaked out of position and the float is dragging. All I
can do is give you suggestions as to what may be
causing your problem.

 

[560Dennis]

Heres Messicks link to the the carburetor for petrol 354
https://www.messicks.com/cas/192810
Suggest check the float for leaks.

 

[Ogrumpyone]

It was running good. Friend said it acted like it ran out of gas. Found out it flooded.

 

[Ogrumpyone]

I will do. Thanks. I've tried 2 different needle and seats but I'll give what you suggested a try.

 

[Ogrumpyone]

The air cleaner is good. This is happening with with or without the air cleaner.

 

[the tractor vet]

Welp never worked on one of them so i have no idea . When stumped on and odd ball then i give harry a call at Benchwick carbs in Youngstown ohio. They have been around a lot of years .

 

[used red MN]

If there is dirt or other crud coming in with the fuel the likely hood of the needle not sealing is pretty high, especially if it is rubber tipped. It gets impregnated into the rubber and then it will not seal. Many carb configurations have a filter or fine screen right inside where the line connects to the carb. This problem is a lot of the reason for that design. On that carb it looks like it connects with a banjo fitting, so no where to place the filter. There is a trick I forgot to mention. You can turn the gas off and run it until it starts running out of gas in the carb. Then open the gas and tap on the carb where the float needle is. When you do this the float needle opens as far as it can, sometimes this flushes the crud out of the needle and then it starts sealing again.