Farmall B No Start...

fixer2u

Member
My dad has a Farmall B that does not want to start easily.
This tractor has an [b:9689e707ae]H4 mag[/b:9689e707ae] but has [b:9689e707ae]6V electric start[/b:9689e707ae].

The tractor has new autolite 3116 plugs, new copper core wires.

I times the tractor per the many posts I have found on this forum.
Pull the No. 1 plug and put your finger in there to feel when it is on the compression stroke. Then look in the plug hole to find TDC. Then check the rotor to make sure it is pointing to No. 1 plug wire.

All was good. We would get a few pops here and there but no start. No throttle condition or choke condition made a difference.

I checked the intake for obstruction and there was none. Replaced the oil in the oil bath. Still no change.

Pulled the plugs and noticed they were dry... Fuel problem?
Added 2 gallons of fresh gas and pulled off the fuel line and had good flow to the carb. (This carb is freshly rebuild by the way. New gaskets, jet, needle & seat, and all passages clean and free.)

Since I had the pre cleaner off I put my hand over it to see if I felt suction as my dad cranked the electric start. I felt suction and it started popping more. Tried again and it started..... Shut it off and tried again. Same result. [b:9689e707ae]We figured out it would only start with my hand over the pre cleaner hole and the throttle all the way closed.[/b:9689e707ae] Choke position made no difference and I double checked the choke was opening and closing properly.

So now I'm thinking vacuum leak. The gasket between the carb and intake was fresh. I tried the old one and no change, tried making a new one out of cork gasket material, no change. I looked for holes in the manifold, but it was hard to tell, I was fresh out of carb cleaner so I was not able to spray around while it was running to listen for changes.


So all that being said, what am I dealing with here? Intake manifold hole?

Again here is a checklist of all that was tried through this ordeal.

- New plugs autolight 3116 gapped per I&T manual
- New copper core wires
- mag coil is new
- 4 different condensers tried 3 of them brand new from tisco
times tractor per procedure mentioned above
- carb rebuilt
- Air cleaner working
- Tried 3 gaskets on carb to intake

Sorry for the very long post, just trying to tell the whole story.
 
As with any engine CHECK the spark at all 4 plugs. You need a blue/white spark that will jump a 1/4 inch gap or more. Fuel the carb means little or nothing unless you have fuel in the carb so pull the carb drain plug and make sure you have a good steady flow of gas for a few minutes. Catch the gas to make sure it does not have dirt/rust/water in it. Holding your hand over the air intake and it starting tells me you not getting enough gas into/out of the carb so good chance the carb is still needing work or not getting enough gas in it due to the float being set wrong
 

There is good blue spark to all 4 plugs.

The float level is set per the standard, there is no hole in the float as I tested it submerged under water to look for bubbles, there is gas getting in the carb as it is dripping out of the overflow after about 2-3 seconds of engine cranking over. The overflow stops a few seconds after cranking telling me the needle is sealing.

I went through that carb with carb cleaner, a small wire brush, long drill bits, and compressed air to get any crud in there out. There really wan't much to start with.
 
I guess I should post too that once you do manage to get it started that it runs great. Here my dad hooked it to a drag to see if it was making good power and it seemed to be. Just does not want to start how or cold. Please ignore the muffler, he got it for free and thought it would be funny to put it on the B.
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Spark color is just one part of what you need. If it will not jump a 1/4 inch gap or more your spark is still to weak
 
did you check for electrical short. check over the mag grounding wire and kill switch.

Had a break on that wire on the B here and if bumped right, it would hit (ground) and the tractor would shut off, and for a time the switch didn't kill it unless just wiggled right. Sometimes it didn't want to start either till the switch was wiggled or wire was pulled off of the switch(to kill we hit the loose end to the frame, or shut the gas off). I don't recall what we did to fix it, or if it just cleared itself.
 
The mag impulse coupling must be making the clicking noise when cranking (hand or starter) if it trip too soon, or not at all, it will give a spark, but not near enough to fire a mix until it is pull started fast enough to create enough engine speed to bypass the impulse. Jim
 

How would the mag affect the tractor only starting with the throttle completely closed and with my hand over the pre cleaner hole?

What am I missing here?
 
An engine with weak spark might fire with the throttle closed because it will have less compression. Normal compression will blow out a weak spark. I too suspect the impulse isn't working. If it had a weak spark full time it would not run well after it does start.

The choke should do the same job as you holding your hand over the air intake. Is the choke plate centered in the air horn? When you put a choke butterfly back in after it has been removed you need to close the choke with the two screws loose to be sure the butterfly is centered and closing all the way around, then tighten the screws. Most engines won't start cold unless the choke butterfly is absolutely totally closed. You probably have checked that already but it's a suggestion. Let us know what you find.[/b]
 
some engines will start differently than others. you may have one of those. and maybe you will figure out the problem, sometimes.



 
Only if the spark is so weak that you are getting the mixture just right with your hand. Very interesting that it will run good when finally started. Does the mag click when cranking slowly by hand? From all the comments, the mag might be your issue. Does it start when you drag it?
 
(quoted from post at 01:31:25 05/27/15) An engine with weak spark might fire with the throttle closed because it will have less compression. Normal compression will blow out a weak spark. I too suspect the impulse isn't working. If it had a weak spark full time it would not run well after it does start.

The choke should do the same job as you holding your hand over the air intake. Is the choke plate centered in the air horn? When you put a choke butterfly back in after it has been removed you need to close the choke with the two screws loose to be sure the butterfly is centered and closing all the way around, then tighten the screws. Most engines won't start cold unless the choke butterfly is absolutely totally closed. You probably have checked that already but it's a suggestion. Let us know what you find.[/b]

Yes I did center the choke in that manner and did check to make sure it is still centered. It needed my hand both when the engine was hot and when it was cold. I never needed the choke when the engine was warm before.
 

It does seem to run strong once we actually get it started. We did just replace the coil because it was fried. So maybe I got a faulty coil?

We did not try pulling the tractor to start it.

I was attempting to adjust the mag to make the impulse trip at TDC and come to think of it I was called away for a few hours while I was doing it so maybe I did not get it just right.


But this still does not answer the question as to why the plugs are not wet after cranking like it is not drawing fuel properly...
 
A couple of years ago a neighbor brought a VAC Case that didn't draw from the carb but that was because of low compression. We did get it running but it ran like crap. You have acceptable compression, i assume, so this this leads us back to the possibility of a vacuum leak, in my mind anyway. Maybe valve lash?
 
A tractor with a big vacuum leak won't run very good when you do get it started. Yours does run good. Since it does have good power running and the impulse coupling is out of service at speed the mag still seems like a possible culprit. The idle circuit in the carburetor may also be suspect. Your hand may be drawing gas through the main jet. I can't remember if the idle circuit is like an H or M where it is an air bleed: turning the screw in gives you a richer mixture. You might try screwing it in.
 
How was you going to adjust the mag. The rotor is pointed at #1 on compression as you said there is no other adjustment if the mags is making fire. Your idle circut in the carb can cause hard starting.
 
(quoted from post at 06:03:34 05/27/15) fixer2u

You just rebuilt The carb, what carburetor type model do you have? picture maybe?

Here is the pic of the carb right after I rebuilt and painted it. I believe it to be a Zenith 9752.

21574.jpg
 
(quoted from post at 12:37:37 05/27/15) How was you going to adjust the mag. The rotor is pointed at #1 on compression as you said there is no other adjustment if the mags is making fire. Your idle circut in the carb can cause hard starting.

I was adjusting the mag by rotating it towards and away from the tractor where it attaches to the tractor via 2, 9/16" bolts.
 
(quoted from post at 07:48:35 05/27/15)
Here is the pic of the carb right after I rebuilt and painted it. . . .

21574.jpg
There's your problem! You have your choke lever clocked to the wrong position. It should point down, not up. This way, the control rod is working backward.
 
(quoted from post at 13:48:35 05/27/15)
(quoted from post at 06:03:34 05/27/15) fixer2u

You just rebuilt The carb, what carburetor type model do you have? picture maybe?

Here is the pic of the carb right after I rebuilt and painted it. I believe it to be a Zenith 9752.

This is a picture of a IHC 1939-46 A, B, AV, Super A Zenith 61AX7 It has an adjustable main jet yours has a plugged main jet that is not adjustable. Maybe Jim Becker can tell you if the orientation is right on this one.

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(quoted from post at 21:21:37 05/27/15)
(quoted from post at 13:48:35 05/27/15)
(quoted from post at 06:03:34 05/27/15) fixer2u

You just rebuilt The carb, what carburetor type model do you have? picture maybe?

Here is the pic of the carb right after I rebuilt and painted it. I believe it to be a Zenith 9752.

This is a picture of a IHC 1939-46 A, B, AV, Super A Zenith 61AX7 It has an adjustable main jet yours has a plugged main jet that is not adjustable. Maybe Jim Becker can tell you if the orientation is right on this one. The the flange and The bore are different on this one as well this is the X7 designation



21574.jpg

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Correct position depends on where the choke butterfly happens to be positioned. This looks right if the choke is nearly open. Ideally, you want the lever to be at 6 o'clock when the choke is half closed. Operating the choke should move the lever about equal distance each side of 6 o'clock.

(quoted from post at 15:52:06 05/27/15)
21585.jpg
 
(quoted from post at 22:06:15 05/27/15) Correct position depends on where the choke butterfly happens to be positioned. This looks right if the choke is nearly open. Ideally, you want the lever to be at 6 o'clock when the choke is half closed. Operating the choke should move the lever about equal distance each side of 6 o'clock.

You really got a good eye for detail Jim nice find. I guess that's why they say a pictures worth a thousand words.

Byron
 
(quoted from post at 22:06:15 05/27/15) Correct position depends on where the choke butterfly happens to be positioned. This looks right if the choke is nearly open. Ideally, you want the lever to be at 6 o'clock when the choke is half closed. Operating the choke should move the lever about equal distance each side of 6 o'clock.

(quoted from post at 15:52:06 05/27/15)
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/quote]

Now I can double check, that the choke is not working as you mentioned, but I did not actually remove the choke rod from the carb when I did the rebuild as the bushings didn't have any play so I didn't think it necessary. That means the choke is in the same position it always was in and had worked in the past prior to the mag frying.
 
I see fresh paint on the carb body and none on the choke arm. I presume you took the arm off, even if you didn't take the shaft out. When you put the arm back, you put it in the wrong position. Either that or it moved by itself. In any case, it is wrong in the picture and needs to be put in the right place. Until that is done, pushing the control rod forward will choke it and pulling it back will open the choke.
 
(quoted from post at 03:21:13 05/28/15) I see fresh paint on the carb body and none on the choke arm. I presume you took the arm off, even if you didn't take the shaft out. When you put the arm back, you put it in the wrong position. Either that or it moved by itself. In any case, it is wrong in the picture and needs to be put in the right place. Until that is done, pushing the control rod forward will choke it and pulling it back will open the choke.

I did not take the choke arm off when I painted it, I just put tape over it. That choke arm is in the same position it was when we bought the tractor 4 years ago. It seemed to us that the choke was working as it should. You pull the lever choke on, push it in choke off.... I will double check though as you suggested. It will be a month or so before I can do that though as the tractor it about 2 hours away from me.
 
Here goes. Did you knock out the Venturi and clean the little holes behind it. That is your idle holes. If your idle air jet does not respond those
holes are pluged. Is your Venturi in upside down. Definitely one of those problems. Roger
 

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