Admitting defeat

Bkpigs · Jul 18, 2019

Well, I finally admitted to defeat with my dad's IH 300U. It started off with a simple carb rebuild early this summer. The tractor was over fueling, black smoke and missing.
Got the carb kit from a reputable carb site. Still no improvement. Replaced the float thinking the float wasn't raising high enough. Still nothing. I adjusted the float to lower the level of fuel. Again, no improvement.
Did a compression test and got 150 psi across the cylinders, adjusted the valves, replaced plugs, wires, cap, rotor, and points since they were showing age any how. Still nothing.
Removed the carb and lowered the fuel level setting again and still no improvement.
All passages in the carb are clean and the idle jet is good.
When I shut the fuel off and let the tractor run out of fuel, it will run perfectly for about 15 seconds right before it runs out of fuel.
Finally told Dad to call someone else to fix it, I am done wasting evenings chasing the problem.
I have rebuilt several carbs and have never run into a problem that eventually I couldn't get figured out and the motor up an running.
Guess you can't win them all.

Janicholson · Jul 18, 2019

The venuri could be in upside down (possible)
The main jet could be too big.
The air cleaner to carb hose could be collapsed inside.
The air cleaner could be plugged up in the screen mesh.
Jim

Bkpigs · Jul 18, 2019

The ventri only fits in one way, right? I disconnected the air inlet to the carb to bypass anything in the intake.

Janicholson · Jul 18, 2019

Has someone drilled out the load screw seat? Is the load screw screwed in and not drilled out? (if it is, then I would replace the main jet)

Bkpigs · Jul 18, 2019

The main jet? I wouldn't think that big tube with holes would ever change to cause an issue. No one has touched the carb for 7 years since he bought it. If you think a new main jet would solve it, I would gladly buy one.

Janicholson · Jul 18, 2019

History is important. Did this issue start at some point, or gradually increase over time. What is the condition of the load screw (bottom front of bowl) they can be
screwed in and broken off, then either fail to do anything (hole plugged) or do not really shut off excess fuel. Look at pictures of new ones. A new main jet can help
if the old one is wrong/drilled/ corroded bigger. Jim

rustred · Jul 18, 2019

have you run the tractor without the intake hose hooked up. the float will not cause a flooding unless it is heavy and full of gas. float is to be set level. sure sounds like u have a restriction in the intake. I presume the choke is open.

Bkpigs · Jul 18, 2019

Dad said it ran fine last year. Started having issues this spring. I removed the load needle and replaced the packing. All looks good and shiny. No rings or ridges.

I will try a new main jet. You have helped me many of times and I really appreciate your help.

ss55 · Jul 18, 2019

Could the air cleaner be restricted, causing a fuel rich mixture? Try disconnecting the air cleaner by removing the air hose to the carburetor.

Jaden · Jul 18, 2019

Does the float still float, or could it have a pinhole allowing it to fill with gas? Shake it and listen if any sloshing sound.

notjustair · Jul 18, 2019

I did that on Saturday. They delivered my new 460m round baler yesterday. I don?t regret anything but
the price tag. Sometimes you have just wasted enough time on something.

Bkpigs · Jul 18, 2019

Jim,
Doing a quick search on the net and a good carb site, I am not finding a new main jet any where. Do you know a place to get a new one?

Ss55 and Rustred,

I have the carb disconnected from the air filter. No change.

Traditional Farmer · Jul 18, 2019

Those rubber type needle valves give me a fit with carbs,half the time they either won't shut the gas off or keep it shut off all the time.I constantly look for the old metal type ones.

fixerupper · Jul 18, 2019

Does the carb run over when the tractor is not running? If the carb does not run over the float is not the problem. I dont think a misadjusted float can make it run THAT bad if the carb is not running over with the engine not running. It might idle rough or maybe put out a little smoke at high idle but it shouldn t make the engine run so rich it won t run.

rustred · Jul 18, 2019

ok, might be a better deal to just get another carb and try it.

Andy Martin · Jul 18, 2019

(quoted from post at 16:37:51 07/18/19) Well, I finally admitted to defeat with my dad's IH 300U. It started off with a simple carb rebuild early this summer. The tractor was over fueling, black smoke and missing.
Got the carb kit from a reputable carb site. Still no improvement. Replaced the float thinking the float wasn't raising high enough. Still nothing. I adjusted the float to lower the level of fuel. Again, no improvement.
Did a compression test and got 150 psi across the cylinders, adjusted the valves, replaced plugs, wires, cap, rotor, and points since they were showing age any how. Still nothing.
Removed the carb and lowered the fuel level setting again and still no improvement.
All passages in the carb are clean and the idle jet is good.
When I shut the fuel off and let the tractor run out of fuel, it will run perfectly for about 15 seconds right before it runs out of fuel.
Finally told Dad to call someone else to fix it, I am done wasting evenings chasing the problem.
I have rebuilt several carbs and have never run into a problem that eventually I couldn't get figured out and the motor up an running.
Guess you can't win them all.

The fact that it runs fine when the gas is shut off tells me it is only the float drabbing on the bowl or something is causing the needle valve to not close. When it quits getting fuel the jets are doing their job.

Did you change the seat above the needle valve? Are you sure you got all the trash out of the inlet to the needle valve?

pete 23 · Jul 18, 2019

Question, can you screw in the main jet adjusting screw and kill the engine when it is running up
to fair speed. If so, forget about main jet because you can lean it out with screw to restrict
flow enough to run decent even if jet is over sized.

Now, on the other hand, if the main jet fell out as it is only lightly pressed in , or got blown
out on cleaning, you would not be able to adjust because needle would not reach in far enough.
Just make sure you can kill engine by screwing in that main jet. Some times too much packing will
not allow you to screw in far enough to adjust and or kill engine.

I have seen the metering nozzle unscrew and cause problem you are having but you certainly would
have corrected that, or idle jet missing. And, if it isn't running over with gas on , engine shut
off, it is not float or needle and seat.

Bkpigs · Jul 19, 2019

(quoted from post at 04:36:38 07/19/19) Question, can you screw in the main jet adjusting screw and kill the engine when it is running up
to fair speed. If so, forget about main jet because you can lean it out with screw to restrict
flow enough to run decent even if jet is over sized.

Now, on the other hand, if the main jet fell out as it is only lightly pressed in , or got blown
out on cleaning, you would not be able to adjust because needle would not reach in far enough.
Just make sure you can kill engine by screwing in that main jet. Some times too much packing will
not allow you to screw in far enough to adjust and or kill engine.

I have seen the metering nozzle unscrew and cause problem you are having but you certainly would
have corrected that, or idle jet missing. And, if it isn't running over with gas on , engine shut
off, it is not float or needle and seat.

I was not able to kill the motor by adjusting the load screw all the way in. How do I remove some of the packing to get it to go all the way in?

rustyfarmall · Jul 19, 2019

(quoted from post at 17:32:20 07/18/19) The ventri only fits in one way, right? I disconnected the air inlet to the carb to bypass anything in the intake.

On those IH carburetors, it is impossible to install the venturi upside down. It physically will not fit any way other than correct.

RBoots · Jul 19, 2019

Did you replace the condensor when you
replaced the other ignition components? A
bad condensor will make one run exactly
like that. Had a non running 35 Massey
show up a couple months ago. Ran just
like yours did. Did same things you did,
just to see where I was with everything.
Points, plugs, wires, cap, and condensor
were new. Checked/Cleaned carb, checked
spark,(plenty hot), points working
correctly, igntion/distributor timing was
correct, float height all good. Got it
started, ran like yours, black smoke,
running poor, missing. Ran better at low
rpm, but not great, ran really bad like
starving for fuel at wide open throttle.
Shot some brake clean in the carb at wide
open throttle and it didn't change a
thing. So I changed the condensor. I've
seen numerous tractors run like that over
the years, changed a lot of condensors
that weren't that old. The new ones are
junk and don't last very long. Had a MF50
the neighbor had that I put 3 condensors
in it in 2 years. The last one must have
been ok, it's been 4 years since that
one. Don't overlook it if you haven't
changed it, it throws the spark timing
off where it will be firing at the wrong
time, loading the cylinders with gas. Try
the brake clean or carb clean experiment.

Bkpigs · Jul 19, 2019

(quoted from post at 15:35:32 07/19/19) Did you replace the condensor when you
replaced the other ignition components? A
bad condensor will make one run exactly
like that. Had a non running 35 Massey
show up a couple months ago. Ran just
like yours did. Did same things you did,
just to see where I was with everything.
Points, plugs, wires, cap, and condensor
were new. Checked/Cleaned carb, checked
spark,(plenty hot), points working
correctly, igntion/distributor timing was
correct, float height all good. Got it
started, ran like yours, black smoke,
running poor, missing. Ran better at low
rpm, but not great, ran really bad like
starving for fuel at wide open throttle.
Shot some brake clean in the carb at wide
open throttle and it didn't change a
thing. So I changed the condensor. I've
seen numerous tractors run like that over
the years, changed a lot of condensors
that weren't that old. The new ones are
junk and don't last very long. Had a MF50
the neighbor had that I put 3 condensors
in it in 2 years. The last one must have
been ok, it's been 4 years since that
one. Don't overlook it if you haven't
changed it, it throws the spark timing
off where it will be firing at the wrong
time, loading the cylinders with gas. Try
the brake clean or carb clean experiment.

What is the brake clean experiment?

Bruce(OR) · Jul 19, 2019

Your comment of, "runs great for 15 seconds before it runs outa gas..."
So less fuel runs better.
Chances are the less fuel is a leaner condition in the cylinder. Less fuel molecules and the hotter the spark is needed to jump
the gap.
So.
Make a hotter spark.
Before you start the engine, loosen the coil wire.
Start the engine.
Running? Now pull the coil wire out of the coil slowly.
Got better didn't it?
Fix the electrical.

JimmyDean · Jul 19, 2019

I just went through this same issue, ended up a weak coil for me, was not hot enough spark to make it run decent.

RBoots · Jul 20, 2019

Spray brake cleaner (the flammable kind),
or carb cleaner into the intake when it's
running poor. If it picks up and runs
better, it's most likely a fuel issue.
And, like I said before, if you didn't
change the condensor, if when you hit it
with the brake cleaner and it doesn't
pick up at all, it's probably the
condensor or a spark related issue.

Bkpigs · Jul 20, 2019

The condenser was replaced. I will try a different one next time I am over there.

Bkpigs · Jul 24, 2019

Well, Pete23 had the correct answer. I didn't have the load needle adjusted. There was too much packing in there and I thought it was bottomed out in the seat. It was not. She runs good now. Thanks everyone!

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