[jp.cole15]

Hello,
I’m new to this forum so thanks in advance for any help! I have a 1978 Farmall 140 that has been an excellent tractor and has never given me any problems to this date! While spraying my garden the tractor just shut down almost like you’d turn the switch off! After a lit researching, I found it needed new points and condenser! I gave her a general overall tuneup including points, condenser, rotor button, distributor cap, plug wires and plugs along with new 12v coil! My tractor fired up like new and will idle fine but when you advance the fuel lever it starts sputtering and popping like it’s out of time! I hooked up my timing light and it looks like it’s good to me! I thought there was a fuel problem because I had to run it with the choke all the way out! I bought a carburetor rebuild kit and cleaned the carburetor and installed the new kit! Tractor fires up and idles and runs great until you try to give it gas by advancing the throttle and then it starts sputtering and popping again doing the same thing it was before! Now I’m NOT sure where to go from there! ANYONE have any suggestions or tell me something different to do?? BTW…I did check the firing order, plug gaps and points gap…all are correct

 

[Bertrrr]

Did you set the points gap correctly ?
is the Carburator linkage sticking possibly ?
Double check the plug wires etc.

 

[pogobill]

Welcome to the forum JP. The tractor must have a governor, perhaps the linkage is sticking? Move it by hand to see if it's working. Also pour some Sea Foam into the gas tank as per instructions, then run the tractor to get the mixture to the carb and let it soak for a day. See if that helps at all.
Was the tractor originally a 12 volt system, or a conversion?

 

[jp.cole15]

Welcome to the forum JP. The tractor must have a governor, perhaps the linkage is sticking? Move it by hand to see if it's working. Also pour some Sea Foam into the gas tank as per instructions, then run the tractor to get the mixture to the carb and let it soak for a day. See if that helps at all.
Was the tractor originally a 12 volt system, or a conversion?

Thanks for the quick reply! Yes the tractor was 12 volts when I bought it however I did buy it from another individual so I’m not sure if it’s ORIGINALLY a 12 volt system! There’s a possibility it could have been a 6v before I bought it I guess! I did move the governor rod and it moves freely so not sure if that’s it or not! I will try the sea foam and see how that works! Thanks for the advice!

 

[jp.cole15]

Did you set the points gap correctly ?
is the Carburator linkage sticking possibly ?
Double check the plug wires etc.

Thanks…I’m pretty sure the gap is correct on the points! I set them at .20 which is what the manual called for! It doesn’t have a magneto so according to the manual it’s supposed to be .20! I feel pretty sure the linkage is freely moving and that’s one of the things that stumps me! I will double check the wires…I’m wondering if one of those is bad as well

 

[mrfred]

Bet you have a bad condenser. See it quite often. New ones are not very good, probably made in china.

 

[jp.cole15]

Bet you have a bad condenser. See it quite often. New ones are not very good, probably made in china.

I certainly thought about that as well so I think I’m gonna try another. Thanks for the insight

 

[MEL NANCE]

If your tractor is indeed a 1978 year it should be factory 12 volt neg, ground , some of the 12 volt systems actually used a 6volt coil with a ballast resistor so if your tractor has a ballast resistor and your new coil is 12 volt or has the built in resistor you could get a weak fire from the coil you can temporary jumper across the ballast to see if it makes a difference ,however based on the fact that you had to run with full choke indicates your orig. problem was fuel related ,there may be a filter screen in the fitting where the fuel line connects to carb. there's also a screen in top of the sediment bowl if either of the screens get clogged up your fuel flow will be restricted , if you open the fuel drain plug on bottom of carb you should get a steady flow of fuel if not work your way back toward fuel tank by disconnecting fuel lines until get fuel flow . Note: if any of you fuel lines are rubber I recommend replacing with lines that can handle fuel that has Ethanol added. "GOOD LUCK"

 

[oletrapper]

Be certain to adjust the points at the .20 on one of the high portions of the rotor which indicates top dead center for that cylinder. And I hope you didn't turn the distributor when replacing anything. If so, your going to need a timing light to get it back where it belongs. Good luck. OT

 

[jp.cole15]

If your tractor is indeed a 1978 year it should be factory 12 volt neg, ground , some of the 12 volt systems actually used a 6volt coil with a ballast resistor so if your tractor has a ballast resistor and your new coil is 12 volt or has the built in resistor you could get a weak fire from the coil you can temporary jumper across the ballast to see if it makes a difference ,however based on the fact that you had to run with full choke indicates your orig. problem was fuel related ,there may be a filter screen in the fitting where the fuel line connects to carb. there's also a screen in top of the sediment bowl if either of the screens get clogged up your fuel flow will be restricted , if you open the fuel drain plug on bottom of carb you should get a steady flow of fuel if not work your way back toward fuel tank by disconnecting fuel lines until get fuel flow . Note: if any of you fuel lines are rubber I recommend replacing with lines that can handle fuel that has Ethanol added. "GOOD LUCK"

Thanks for the help! According to all I can find out, the tractor is a 78 model! The coil I changed out was exactly like the one I took off of it and it didn’t make a difference in the engine sputtering and coughing. It ran great prior to me doing the tuneup so I suspect that the coil is probably fine! I’ve rebuilt the carburetor and replaced the screen in the fuel line and that didn’t help either! It’s GOTTA be something in the firing system I would think! I’ve been told the points gap is between .16-.18 but the manual reads .20 (for non magneto type distributors) but none of that made any difference in the problem! I’m completely stumped!

 

[Bertrrr]

I've run across similar situations and found a cracked distributor cap causing the fire to go nuts and act like it's totally out of time, also found carbon type plug wires burnt way back was what caused the spark to start jumping around inside the cap. Doubtful you would be able to see the crack without magnafying glass tho.

 

[Fotoguzzi]

Did you replace the condenser yet?

 

[Rolex]

Will it perform differently with the choke in use or the air filter disconnected ?

It could be a fuel issue after the carb rebuild

If it runs better with the choke on it needs more fuel, if it runs better with the air filter disconnected you want less fuel

 

[jp.cole15]

I've run across similar situations and found a cracked distributor cap causing the fire to go nuts and act like it's totally out of time, also found carbon type plug wires burnt way back was what caused the spark to start jumping around inside the cap. Doubtful you would be able to see the crack without magnafying glass tho.

…humm, that’s the next thing I’ll check then. Thanks

 

[jp.cole15]

Did you replace the condenser yet?

Yes…replaced it yesterday but no difference. I’m gonna start ALL OVER again and remove the points and put new ones back in

 

[jp.cole15]

Will it perform differently with the choke in use or the air filter disconnected ?

It could be a fuel issue after the carb rebuild

If it runs better with the choke on it needs more fuel, if it runs better with the air filter disconnected you want less fuel

No it performs the same way! When the engine warms up just idling I can push the choke in and it still runs fine at idle…but as soon as you push the throttle forward it starts popping and sputtering again!! 🤷‍♂️

 

[jp.cole15]

Be certain to adjust the points at the .20 on one of the high portions of the rotor which indicates top dead center for that cylinder. And I hope you didn't turn the distributor when replacing anything. If so, your going to need a timing light to get it back where it belongs. Good luck. OT

Thanks…I was told that .20 was a little too much and they should be .16 - .18 but I did that as well with no change! I don’t think I turned the distributor as I did do a timing light check to make sure that it was timed correctly! Never set the timing on a Farmall before but when I looked at it with the timing light it looked like it was dead center of the marks! So I’m “assuming” that’s the way it should look! Is that correct?

 

[jp.cole15]

WELLLLL….this was the culprit after all! The brand new coil was causing the problem the whole time! I reinstalled my old coil back on it and it ran like a top even when I pushed the throttle lever to wide open!! I’ve learned a good lesson about “nothing beats a check other than a re-check!” Thanks to everyone who gave me input into my problem!

 

[mrfred]

Glad you figured it out. A couple years ago, on a farmall 350 the condenser mounting clamp would not tighten the condenser tight and did not have a good ground. Ended up wrapping the condenser with tin foil, so it would ground good when tight in the clamp. That tractor would act like yours would, idle fine but would not throttle up without bucking and backfiring.

 

[jp.cole15]

Glad you figured it out. A couple years ago, on a farmall 350 the condenser mounting clamp would not tighten the condenser tight and did not have a good ground. Ended up wrapping the condenser with tin foil, so it would ground good when tight in the clamp. That tractor would act like yours would, idle fine but would not throttle up without bucking and backfiring.

I kinda consider myself a pretty smart mechanic since I worked on Tanks and Artillery for 35 years but this tractor made me realize I’m not the “mechanic” I thought I was!! LOLO….tractors ARE ANLOY DIFFERENT THAN TANKS! Haha. I had a feeling that would be something simply when I figured it out and it was!