Carb Issues

   / Carb Issues #1  
slhilbert

slhilbert

Bronze Member
Joined
Aug 21, 2013
Messages
75
Location
Noblesville IN
Tractor
Massey Ferguson 135
I am in the process of putting my tractor back together after replacing the clutch. One of the last issues I am facing is that the Carb is "Butterflying". I use to have a solenoid that went into the bottom of the carb and would shut it off the fuel to the carb when you turned it off, that solenoid went bad so I replaced it with a needle that seems to work fine. This tractor ran just fine before I split it for the clutch. I have messed with the mixture screw, but maybe I am doing it wrong. Here is a video showing what it is doing at idle.


If I give it gas I get some flames coming out of the air intake and lots of back fires.

Thanks,
Stuart
 
   / Carb Issues #2  
How long has it sat not running ? It is firing back through the intake valve. valve is sticking or possible spark plug wire in wrong order or cracked distributor cap.The erratic pattern sounds like sticky intake valve. Unplug and plug back in each spark plug wire until you find the cylinder that stops the backfire.
 
   / Carb Issues
  • Thread Starter
#3  
I last ran it, early September, but it really hasn't been used since May when the clutch went out.

Yes, it is firing back through the intake valve.

I am pretty sure the spark plug order is right as any other combo and I get crazy back fires out the tail pipe.

When you say unplug the plugs, I assume while it is running?

Stuart
 
   / Carb Issues #4  
It would be best if it was running to hear the difference, but you might get a shock if the wire is leaking. three cylinder it wont take long. When and if you have to remove the valve cover so you can work penetrate around the valve stem and work it up and down it would be nice to know for sure which one it is, it is most likely just varnish in the valve guide and might come out of it with some Bardah and let it run long enough to get hot and oil in the head area.BARDAHL Pro -Strength Engine Tune Up 11 z | eBayl
 
   / Carb Issues
  • Thread Starter
#6  
   / Carb Issues #7  
It will be on top two times, one will be on exhaust and one on compression, you want the compression, this will be with both valves shut, put your finger over the spark plug hole and turn the engine over until the compression blow your finger up off the hole. It wont have to be exact just close enough to pick a spark plug wire hole on the cap as number one . lift the cap and see which hole it is pointing at and plug in the spark plug wire from number one cylinder. You need to know which direction the rotor turns so you can plug in the other two wires, it was firing order 123, counter clockwise ? or clockwise?
 
   / Carb Issues
  • Thread Starter
#8  
I messed with the carb tonight some more and I ended up with a tractor that can idle like a champ but pops when you rev it.

I got the idle working by messing with the "main jet" which controls fuel entering into the carb. Once I get that pretty cranked down then I can mess with the mixture to get a good idle, but when I try to give it gas it hates it.

Does that tell you anything?

I know the spark order is 1,2,3 and it goes clockwise. I believe I have the plugs in the right order because if I try the other orders it backfires and carries on.

Stuart
 
   / Carb Issues #9  
slhilbert said:
I messed with the carb tonight some more and I ended up with a tractor that can idle like a champ but pops when you rev it.

I got the idle working by messing with the "main jet" which controls fuel entering into the carb. Once I get that pretty cranked down then I can mess with the mixture to get a good idle, but when I try to give it gas it hates it.

Does that tell you anything?

I know the spark order is 1,2,3 and it goes clockwise. I believe I have the plugs in the right order because if I try the other orders it backfires and carries on.

Stuart
Click to expand...

Check the ignition timing and make sure the centrifugal advance is working. If you don't know how, get back to me a and I'll tell you how to do it..
 
   / Carb Issues #10  
Hi Stuart, I am having trouble believing the valve stem started sticking in a few months I keep searching in my mind other popping back and coughing tractors I have had. I remember one that did not charge and I had to put it on a charger for awhile to use it. When the battery would get down to around 11 volt it would loose horse power and start coughing and popping and get worse as voltage dropped . Because I know your history with the wiring I would like for you to check the voltage at the coil when it is running. The idling fair and getting worse as the rpm increase would agree with this theory, A quick and simple test would be wire direct from your positive bat term to the coil after checking that your battery is up. I love a puzzle, when it is not mine LOL
 
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