Ford 4000 poor running when warm

[Superbros8]

I have a ford 4000 with the 3 cylinder gas engine, it runs great when it’s cool but once you worked it for a bit 15-20 minutes and thoroughly warmed the engine it will stutter severely and stall when you try rev the engine up, if you play with the throttle it’ll catch and go and once you’ve done that it’ll run and take a load again and whatnot but it struggles with acceleration in the lower 1/3-1/2 of the RPM range. I also noticed that it has a strong spark when just running at any steady RPM but once you add throttle to accelerate it will weaken somewhat and at that point start to stutter and miss, noticed it across all three spark plug wires, coil ohm’s out at about 3.5-3.8 ohms, I’m getting 12.5-12.6 volts to it, tractor is charging at about 13.8-14.4v, tested spark with a lisle spark tester with the little bulb element inside. Tank is clean, sediment bowl behind carb is clean with fresh screen, I cleaned up the contacts inside the distributor, have messed with timing and fuel mixture screw, not having any luck, any suggestions?

 

[Janicholson]

I have a ford 4000 with the 3 cylinder gas engine, it runs great when it’s cool but once you worked it for a bit 15-20 minutes and thoroughly warmed the engine it will stutter severely and stall when you try rev the engine up, if you play with the throttle it’ll catch and go and once you’ve done that it’ll run and take a load again and whatnot but it struggles with acceleration in the lower 1/3-1/2 of the RPM range. I also noticed that it has a strong spark when just running at any steady RPM but once you add throttle to accelerate it will weaken somewhat and at that point start to stutter and miss, noticed it across all three spark plug wires, coil ohm’s out at about 3.5-3.8 ohms, I’m getting 12.5-12.6 volts to it, tractor is charging at about 13.8-14.4v, tested spark with a lisle spark tester with the little bulb element inside. Tank is clean, sediment bowl behind carb is clean with fresh screen, I cleaned up the contacts inside the distributor, have messed with timing and fuel mixture screw, not having any luck, any suggestions?

When it happens feel the coil. if it is nasty hot, it is going bad. A bad condenser will also do that. as will a plugged up vent in the fuel tank cap. one more thing is distributor cam shaft bushing wear. if you can move it sideways at all (up down away and towards you it is in need of rebuilding. Jim

 

[Superbros8]

When it happens feel the coil. if it is nasty hot, it is going bad. A bad condenser will also do that. as will a plugged up vent in the fuel tank cap. one more thing is distributor cam shaft bushing wear. if you can move it sideways at all (up down away and towards you it is in need of rebuilding. Jim

The coil was warm but you could still comfortably hold it even when running, idk if this one has a condenser, it doesn’t look to have points either, I can let it sit and pull the cap and with some heat still in the engine start it and it will still stutter so I don’t believe it is a venting issue, haven’t noticed a vacuum in the tank either. But I will definitely look into the bushing wear. And is that the shaft inside the distributor?

 

[Janicholson]

The coil was warm but you could still comfortably hold it even when running, idk if this one has a condenser, it doesn’t look to have points either, I can let it sit and pull the cap and with some heat still in the engine start it and it will still stutter so I don’t believe it is a venting issue, haven’t noticed a vacuum in the tank either. But I will definitely look into the bushing wear. And is that the shaft inside the distributor?

Yes. The heated coil must be checked when the issue is happening. A coil can fail internally and still not heat much though heat is a suer thing. Jim

 

[Superbros8]

Yes. The heated coil must be checked when the issue is happening. A coil can fail internally and still not heat much though heat is a suer thing. Jim

I ohm’d the coil less than a minute after shutting down and it was at 3.7-3.8, is there any other way to check for a bad coil other than replacing

 

[used red MN]

Hello Super.., welcome to YT! I am thinking you have an inadequate fuel delivery problem. Get a pint jar, something that will measure a pint. Open the carb bowl drain and let it drain about 5 seconds. This lets the carb bowl drain so the test is not thrown off. Then begin catching the fuel for a timed two minutes. Should fill the pint measure in those two minutes. If it does not run enough fuel out of the carb drain to fill it recheck it at the line disconnected from the carb. Here you can immediately start the test on this line. If it has good flow there it is possible that the fitting that the fuel line connects that screws into the carb has a fine screen on it that can plug. Pull it out and check it. Some models have them and some don't. If the flow is not good enough out of the line you have to figure out where it is getting blocked. It may be the screen on the outlet to the sediment bowl in the tank. Take a good flashlight and look in the bottom of the tank to check for an abnormal amount of debris in the gas The 2 minutes for a pint calculates to be 3:75 gph, this is what your tractor consumed when tested under load. There was one higher gph number but I doubt you’re pulling it that hard.

 

[Superbros8]

Hello Super.., welcome to YT! I am thinking you have an inadequate fuel delivery problem. Get a pint jar, something that will measure a pint. Open the carb bowl drain and let it drain about 5 seconds. This lets the carb bowl drain so the test is not thrown off. Then begin catching the fuel for a timed two minutes. Should fill the pint measure in those two minutes. If it does not run enough fuel out of the carb drain to fill it recheck it at the line disconnected from the carb. Here you can immediately start the test on this line. If it has good flow there it is possible that the fitting that the fuel line connects that screws into the carb has a fine screen on it that can plug. Pull it out and check it. Some models have them and some don't. If the flow is not good enough out of the line you have to figure out where it is getting blocked. It may be the screen on the outlet to the sediment bowl in the tank. Take a good flashlight and look in the bottom of the tank to check for an abnormal amount of debris in the gas The 2 minutes for a pint calculates to be 3:75 gph, this is what your tractor consumed when tested under load. There was one higher gph number but I doubt you’re pulling it that hard.

My tank is clear, just rechecked it last night, and I’ll do a flow test, I’m assuming this test will be with me just cranking the engine?

 

[used red MN]

Oops, sorry didn’t realize your tractor has a fuel pump that test process is for a gravity flow system. Please don’t crank the starter two minutes. Disconnect the line from the carb and direct it into something and start the engine. Should easily pump a cup in 30 seconds. While the line is disconnected pull the fitting out of the carb to verify the strainer screen is clean or that it doesn’t have one.

 

[Janicholson]

I ohm’d the coil less than a minute after shutting down and it was at 3.7-3.8, is there any other way to check for a bad coil other than replacing

Not questioning your process, but at low ohm readings meters often are off quite a bit. that spark test is critical, allowing you to assess the capability of the coil to push spark. by seeing if it will jump a 1/4 inch gap to the block. If it is thready and yellow it is not going to fire plugs. if crisp and blue white. it is good. Jim

 

[Janicholson]

Not questioning your process, but at low ohm readings meters often are off quite a bit. One way to assess the performance of the coil id a spark test. there are gap adjustable tools, or you could do it with insulated plug wire pliers. They allow you to assess the capability of the coil to push spark. by seeing if it will jump a 1/4 inch gap to the block. If it is thready and yellow it is not going to fire plugs. if crisp and blue white. it is good. Jim

one more item. if the manifold is loose or cracked it can make those symptoms. Jim

 

[Superbros8]

Not questioning your process, but at low ohm readings meters often are off quite a bit. One way to assess the performance of the coil id a spark test. there are gap adjustable tools, or you could do it with insulated plug wire pliers. They allow you to assess the capability of the coil to push spark. by seeing if it will jump a 1/4 inch gap to the block. If it is thready and yellow it is not going to fire plugs. if crisp and blue white. it is good. Jim

Not questioning your process, but at low ohm readings meters often are off quite a bit. One way to assess the performance of the coil id a spark test. there are gap adjustable tools, or you could do it with insulated plug wire pliers. They allow you to assess the capability of the coil to push spark. by seeing if it will jump a 1/4 inch gap to the block. If it is thready and yellow it is not going to fire plugs. if crisp and blue white. it is good. Jim

not saying you were, apologies if it came off that way, and agreed there’s always a chance for false readings with equipment, but it seems to have good spark until I add throttle and then I can see a noticeable dimming of the spark in the spark tester until it catches up and it regains strength, and I’ll have to see about acquiring an adjustable gap tester.

 

[Superbros8]

one more item. if the manifold is loose or cracked it can make those symptoms. Jim

Are there any common area to check for cracks? I sprayed the intake down with carb cleaner with the engine about half throttle to see if it would pull any in and act up and had no luck but I very well could’ve missed something

 

[Janicholson]

The compression pressure causes spark to more difficult to jump the plug gap. so the spark intensity might be going the wrong way. a new coil from an autoparts store is less expensive than spending more hours diagnosing it. Jim

 

[Superbros8]

The compression pressure causes spark to more difficult to jump the plug gap. so the spark intensity might be going the wrong way. a new coil from an autoparts store is less expensive than spending more hours diagnosing it. Jim

Sounds good, so I just need a 12v 3ohm coil then?

 

[Janicholson]

Are there any common area to check for cracks? I sprayed the intake down with carb cleaner with the engine about half throttle to see if it would pull any in and act up and had no luck but I very well could’ve missed something

Letting us know what you already did is important. that should have made a noticeable difference. Try this as well. Use an unlit propane torch with the nozzle removed aimed into the carb intake. this will richen the mixture and might show a partially clogged passage in the carb. Jim

 

[Superbros8]

Also here’s the inside of my distributor

 

[Janicholson]

Sounds good, so I just need a 12v 3ohm coil then?

Assuming that is what is in it, yes. 3.2 to 3.4 ohms. The intent is to have the ignition use maybe 4 amps. (at operating charging voltage. Jim

 

[Superbros8]

Oops, sorry didn’t realize your tractor has a fuel pump that test process is for a gravity flow system. Please don’t crank the starter two minutes. Disconnect the line from the carb and direct it into something and start the engine. Should easily pump a cup in 30 seconds. While the line is disconnected pull the fitting out of the carb to verify the strainer screen is clean or that it doesn’t have one.

All good, figured it’d be worth an ask before I sat and cranked on it, but I’ll definitely check that strainer.

 

[Superbros8]

Assuming that is what is in it, yes. 3.2 to 3.4 ohms. The intent is to have the ignition use maybe 4 amps. (at operating charging voltage. Jim

Sounds good, appreciate the help!

 

[Janicholson]

Also here’s the inside of my distributor

Electronic ignition. that is good. Ignore the distributor shaft issue in prior posts. Jim