Farmall 140 running rough - why?

[MF in Canada]

Hi folks - I'm getting to know my new-to-me 1968 Farmall 140. Great machine.

I replaced the plugs and wires when she was running a bit rough earlier this summer, and that seemed to smooth things out nicely. Now, spontaneously, she's running rough again. Idles fine, but under load she's spluttering and not happy.

So... can anyone give me a list of things to troubleshoot this problem?

I'd be happy to do a complete tuneup - just to get on a solid baseline. Does anyone have NAPA numbers for distributor parts, etc?

I'm the kind of farmer that can do the mechanics if I know what to do - I'm just not that good with gas engine troubleshooting.

Thanks for any and all advice.
Eric

 

[Janicholson]

Use a clean open topped can and pull the plug out of the bottom of the carb. it will flood at first into the can then slow to a flow that should make a pint in 2 minutes or less. If not there is a fuel delivery issue. If that is fine, you can see if pulling the choke part way smoothes it. If yes, there is some trash/blockage in the carb main jet. Jim

 

[crsutton81]

Hi folks - I'm getting to know my new-to-me 1968 Farmall 140. Great machine.

I replaced the plugs and wires when she was running a bit rough earlier this summer, and that seemed to smooth things out nicely. Now, spontaneously, she's running rough again. Idles fine, but under load she's spluttering and not happy.

So... can anyone give me a list of things to troubleshoot this problem?

I'd be happy to do a complete tuneup - just to get on a solid baseline. Does anyone have NAPA numbers for distributor parts, etc?

I'm the kind of farmer that can do the mechanics if I know what to do - I'm just not that good with gas engine troubleshooting.

Thanks for any and all advice.
Eric

Sounds as there may be a possible fuel restriction problem. Where the fuel line from the tank connects up to the carb, there is a filter screen in that connector on the carb side. Ensure that it has not partially plugged.

 

[used red MN]

Pull the plugs out angain and look to see if they have oil/carbon residue on them. Maybe it is starting to use more oil than you think.

 

[Brownie450]

I'd suspect the condenser, even though it has been replaced recently.
Jim

 

[MF in Canada]

Thanks so much folks. I'll get onto this sometime this week and let you know the results. I much appreciate your experienced assistance.

Eric

 

[MF in Canada]

Hello again - just got to working on the 140.

I cleaned the little filter (Thanks: crsutton81). It had a very small amount of black specks in it, but not much. I also cleaned the sediment bowl which also had some black specks on the bottom, like fine sand.

I pulled the plug on the bottom of the carb (Thanks: Janicholson). The stream of gas did as you said: flood a bit, and then trickle. In 2 minutes, it filled about a cup. This did not change appreciably after cleaning the filter. That's about half of what you said it should do in 2 minutes. Pulling the choke did nothing to change the flow of fuel.

I also pulled the plugs and looked at them (Thanks: used red MN). They are all black, but the rear three are clean around the electrodes. The front one is black even on the electrodes.

Two other things I did: I put my hand on top of the air breather hole (above valves) and there is no blow-by: no air pressure coming out that hole. And I changed the oil in the oil-bath air filter. It smelled a bit like gas and was dark. I had changed it earlier in the summer, but it seems to fill with gas if I ever forget to close that petcock on the sediment bowl.

I mention those two things in case they give a clue as to what's going on.

So, IF a cup of fuel is enough in 2 minutes (Is it?)

Then the problem is more in the fuel mixture or its burning oil.

Thus I'd like to think we have a fuel/air mixture problem. Is this carburetor adjustable?? (I note that the tractor starts even in cool weather with no choke. Perhaps it is just running rich.)

Your thoughts, guidance, and experience are again sought after! I'll attach some pics in a minute.

Thanks,
Eric

ps. nice to see replies from MN. I lived in Ely when I was in my 20's.

 

[MF in Canada]

Some pics: plugs and carb

 

[560Dennis]

its good you posted the plugs photos .
here a chart to help you on plugs

http://1.bp.blogspot.com/-BpC43BNUt1g/UU4PupmIkWI/AAAAAAAAA2I/vDn5VYuUehs/s1600/spark_plug_chart.jpg

 

[caterpillar guy]

Sounds like the fuel flow in the bottom of the carb is a bit low. I would clean the sediment bowl and screen in the top of it. Then check screen at carb where line screws in. IF all is good then your into the carb adjustments and cleaning. Jim meant to pull the choke while it is running to see if it made a difference in running when it acts up as a test for the fuel supply .

 

[crsutton81]

Hello again - just got to working on the 140.

I cleaned the little filter (Thanks: crsutton81). It had a very small amount of black specks in it, but not much. I also cleaned the sediment bowl which also had some black specks on the bottom, like fine sand.

I pulled the plug on the bottom of the carb (Thanks: Janicholson). The stream of gas did as you said: flood a bit, and then trickle. In 2 minutes, it filled about a cup. This did not change appreciably after cleaning the filter. That's about half of what you said it should do in 2 minutes. Pulling the choke did nothing to change the flow of fuel.

I also pulled the plugs and looked at them (Thanks: used red MN). They are all black, but the rear three are clean around the electrodes. The front one is black even on the electrodes.

Two other things I did: I put my hand on top of the air breather hole (above valves) and there is no blow-by: no air pressure coming out that hole. And I changed the oil in the oil-bath air filter. It smelled a bit like gas and was dark. I had changed it earlier in the summer, but it seems to fill with gas if I ever forget to close that petcock on the sediment bowl.

I mention those two things in case they give a clue as to what's going on.

So, IF a cup of fuel is enough in 2 minutes (Is it?)

Then the problem is more in the fuel mixture or its burning oil.

Thus I'd like to think we have a fuel/air mixture problem. Is this carburetor adjustable?? (I note that the tractor starts even in cool weather with no choke. Perhaps it is just running rich.)

Your thoughts, guidance, and experience are again sought after! I'll attach some pics in a minute.

Thanks,
Eric

ps. nice to see replies from MN. I lived in Ely when I was in my 20's.

I still think you possibly have a low fuel flow issue. Here's a test to try...with it warmed up a bit, pull the choke and see if it helps keeping it from stumbling. It should run a bit rich and sorta want to act a bit like it's flooding it. If it's better while using the choke, the fuel supply is a bit short. I noticed that you mentioned the fact that there is a screen in the top of your sediment bowl. I have found from our experiences here that these screens restrict the flow just enough to make the 1 row Farmalls stumble and lack power under a load. I have been removing them and had no troubles since. If you're gas tank is clean and you keep the fuel supply clean, they're not needed. If the tank has some loose sediment in it, now would be a good time to pull the tank and wash it out. Really small fine rust particles will still collect in the bottom of the sediment bowl if present.

 

[MF in Canada]

Thanks 560Dennis, crsutton81 and caterpillar guy.

I believe there was LOTS of fuel flowing out of the line once I disconnected it from the carb this afternoon. I'll check again tomorrow to be sure. If necessary I will remove that screen above the sediment bowl. (Thanks crsutton81). I will also try your choke suggestion.

However, at the moment I think any fuel supply restriction is IN the carb, not before it. I did clean that little filter in the elbow on the carb. Lots of compressed air...

I pulled a couple plugs again this evening, and found that the front one, which is worst, was wet and smelled like gas. I had run the tractor for a minute or two late this afternoon. The second plug was coated with a dry carbon.

So, we may have more than one problem. A rich mix and an ignition problem.

I'm coming to the conclusion that I'd like to give this old tractor a thorough tune-up. Fix it all now, instead of a little at a time during the growing season. So:

1. does anyone have instructions on carb cleaning and adjustments? My carb is pictured above in this thread.
2. having already done the plugs and wires, I what is left to do on the ignition system?
replace the distributor cap and rotor?
replace points and condenser?
Or would you suggest going to electronic ignition - I believe that is the modern way to go.
If so, does anyone have a recommended brand and/or source for electronic ignition (I live in Canada)
3. I have read also that when going to electronic ignition it is wise to replace the coil at the same time. True??

I've worked on this stuff before, but it was a LONG time ago.

Thanks so much, your advice is greatly appreciated.

Eric

 

[riverbend]

Try spraying the inside of the distributor cap with WD40. Swirl it a round a bit and dump it out. Wipe the cap as dry as possible. Does that help ?

Most carburetor problems are ignition related...

 

[Jim Becker]

You could have a small bit of trash in the carburetor partly plugging the float valve. Another problem may be the #1 spark plug or the #1 spark plug wire (even if they are new). You are using solid core ignition wire, aren't you?

 

[crsutton81]

Thanks 560Dennis, crsutton81 and caterpillar guy.

I believe there was LOTS of fuel flowing out of the line once I disconnected it from the carb this afternoon. I'll check again tomorrow to be sure. If necessary I will remove that screen above the sediment bowl. (Thanks crsutton81). I will also try your choke suggestion.

However, at the moment I think any fuel supply restriction is IN the carb, not before it. I did clean that little filter in the elbow on the carb. Lots of compressed air...

I pulled a couple plugs again this evening, and found that the front one, which is worst, was wet and smelled like gas. I had run the tractor for a minute or two late this afternoon. The second plug was coated with a dry carbon.

So, we may have more than one problem. A rich mix and an ignition problem.

I'm coming to the conclusion that I'd like to give this old tractor a thorough tune-up. Fix it all now, instead of a little at a time during the growing season. So:

1. does anyone have instructions on carb cleaning and adjustments? My carb is pictured above in this thread.
2. having already done the plugs and wires, I what is left to do on the ignition system?
replace the distributor cap and rotor?
replace points and condenser?
Or would you suggest going to electronic ignition - I believe that is the modern way to go.
If so, does anyone have a recommended brand and/or source for electronic ignition (I live in Canada)
3. I have read also that when going to electronic ignition it is wise to replace the coil at the same time. True??

I've worked on this stuff before, but it was a LONG time ago.

Thanks so much, your advice is greatly appreciated.

Eric

I just noticed the pictures that were posted. That looks like a Marvel Schebler carb from here. Everyone has they're preferences on things, but those carbs have left a lot to be desired for, for myself and area I live in. They either keep it borderline flooded or make it lack power....not much in between. I have changed several over to the original Zenith style carbs and it made a night and day difference in that parts swap alone. No more flooding, has more power, and much snappier throttle response. On the ignition system...if the tractor is going to be used at all, we are installing Pertronix electronic ignition on them with excellent results. Be advised though that if this is done that suppression plug wires need to be installed. A good spark plug to use with this combo is an Autolite 386 or 388 for a tad hotter plug. Both are resistor plugs. A regular coil of your tractors voltage system ( 6 or 12 volt, should be 12 volt for a '68 year model ) is adequate a plenty with no external resistor required.

 

[MF in Canada]

Hello and Thank you all.

Today I had only a little time to work on this, but I took the screen out of the sediment cup assembly. It was fairly clean, but I cleaned it anyway.

I found that there was a piece of crud actually blocking the opening where fuel comes from the tank. I removed that and the fuel flows MUCH faster out of the line when it's not hooked to the carb.

I ran out of time to try pulling the plug on the carb and see how much I get in 2 minutes.

However, in removing the piece of crud in the sediment cup assembly, I also accidentally knocked out that tiny little brass disc - the size of a paper punch hole. I cannot get that thing to stay back up in there for the life of me. Is it a press-fit thing? Or when it fell out did I also lose some kind of clip?

The related question of course, is whether that little brass disc is necessary? I expect it is there to keep fuel from entering the cup in a straight line, and thus it keeps the sediment at the bottom of the cup from getting stirred up.

Does anyone know about this little brass disc?

Thanks again,
Eric

 

[MF in Canada]

And to reply to your other comments - thank you for all the suggestions. I did pull off the distributor cap just to peek, and it looked a bit corroded here and there. I buffed it up with emery cloth and put it back together. The tractor still runs. I will clean it better or simply replace it in the next little while.

I will look into the electronic ignition: Pertronix. Thank you. I will also look into the Zenith style carb.

plugs: I will end up trying to clean these, but probably replace them. Thanks for the Autolite numbers.

wires: solid core wires? I got wires from the local Case IH dealer (Aftermarket wires A&I products), and they are a stranded copper wire. That seems like "solid core", meaning it is copper, not carbon.

I think I need a tutorial on Resistor and Non-Resistor parts and when to use them.

I currently have Autolite 3116 plugs, a non-resistor plug. I believe this is correct with the old points and condenser system. And this goes with the solid core/copper wire. Minimum resistance gives maximum spark.

If I go to electronic ignition, I need resistor plugs like the Autolite 386 or 388 and suppression wires. To keep the electronic parts safe/protected. Is that correct?

It was Burch Store Tractors who suggested a new coil with the electronic ignition - a hotter coil, they say. Its a Pertronix coil that they sell/recommend.

I'm happy to do it if it will make everything more reliable. In the growing season I don't have much time for being a mechanic - I'd like this tractor to be basically reliable day in and day out. Any further thoughts on the coil?

Thanks again - really appreciate the help on what might be "basic" to some of you.
Eric

 

[crsutton81]

And to reply to your other comments - thank you for all the suggestions. I did pull off the distributor cap just to peek, and it looked a bit corroded here and there. I buffed it up with emery cloth and put it back together. The tractor still runs. I will clean it better or simply replace it in the next little while.

I will look into the electronic ignition: Pertronix. Thank you. I will also look into the Zenith style carb.

plugs: I will end up trying to clean these, but probably replace them. Thanks for the Autolite numbers.

wires: solid core wires? I got wires from the local Case IH dealer (Aftermarket wires A&I products), and they are a stranded copper wire. That seems like "solid core", meaning it is copper, not carbon.

I think I need a tutorial on Resistor and Non-Resistor parts and when to use them.

I currently have Autolite 3116 plugs, a non-resistor plug. I believe this is correct with the old points and condenser system. And this goes with the solid core/copper wire. Minimum resistance gives maximum spark.

If I go to electronic ignition, I need resistor plugs like the Autolite 386 or 388 and suppression wires. To keep the electronic parts safe/protected. Is that correct?

It was Burch Store Tractors who suggested a new coil with the electronic ignition - a hotter coil, they say. Its a Pertronix coil that they sell/recommend.

I'm happy to do it if it will make everything more reliable. In the growing season I don't have much time for being a mechanic - I'd like this tractor to be basically reliable day in and day out. Any further thoughts on the coil?

Thanks again - really appreciate the help on what might be "basic" to some of you.
Eric

Just some random thoughts.....If you have a good working coil now, I would not replace it in the event that you did change over from a points system to electronic ignition. You do however need to have a full 6 or 12 volts depending on system voltage supplying the EI system and coil straight from the kill switch. The oldest EI conversion here on the farm is on our 100 which was done about 25 years ago, and still using a regular coil with no problems at all. To keep from having any warranty issues on an EI setup, the suppression plug wires are to be used, not solid core ( copper or aluminum). I have seen them used with mixed results though. The Autolite 3116 plugs are a good match in my opinion for a points system with copper wires. I want to think that 388 resistor plugs are the same heat range as the 3116's, which are not resistor.

 

[grandpa Love]

Hello and Thank you all.

Today I had only a little time to work on this, but I took the screen out of the sediment cup assembly. It was fairly clean, but I cleaned it anyway.

I found that there was a piece of crud actually blocking the opening where fuel comes from the tank. I removed that and the fuel flows MUCH faster out of the line when it's not hooked to the carb.

I ran out of time to try pulling the plug on the carb and see how much I get in 2 minutes.

However, in removing the piece of crud in the sediment cup assembly, I also accidentally knocked out that tiny little brass disc - the size of a paper punch hole. I cannot get that thing to stay back up in there for the life of me. Is it a press-fit thing? Or when it fell out did I also lose some kind of clip?

The related question of course, is whether that little brass disc is necessary? I expect it is there to keep fuel from entering the cup in a straight line, and thus it keeps the sediment at the bottom of the cup from getting stirred up.

Does anyone know about this little brass disc?

Thanks again,
Eric

I believe you are correct about the little brass disk.....it simply keeps the gas from running straight in. If the bowl is clean it shouldn't be an issue if it's missing .

 

[Straanger]

You mentioned fine black particles, like sand. That says to me that you may have an old fuel line that is starting to break down inside.
If you replace it, make sure to use “green line “ that is designed for use with ethanol fuels.