4020 loss of engine Power

[Client]

HELP! My 1966 JD4020 diesel starts great, runs great while bush hogging for 20 to 30 minutes, then it gradually starts to bogg down and ultimately dies. Increased throttle with no RPM change. I changed the fuel filters hoping it might help in correcting the problem, which it did not. Also, I drained some fuel from the pit cock and it appears fine. My thoughts lean toward fuel starvation/restriction when reaching operating temp. I'm certainly an amateur that is humbly asking for help!

 

[Fordy20]

HELP! My 1966 JD4020 diesel starts great, runs great while bush hogging for 20 to 30 minutes, then it gradually starts to bogg down and ultimately dies. Increased throttle with no RPM change. I changed the fuel filters hoping it might help in correcting the problem, which it did not. Also, I drained some fuel from the pit cock and it appears fine. My thoughts lean toward fuel starvation/restriction when reaching operating temp. I'm certainly an amateur that is humbly asking for help!

You might try loosening the fuel cap to make sure the cap is venting.

 

[Client]

You might try loosening the fuel cap to make sure the cap is venting.

I will try that, and thank you.

 

[Bob Bancroft]

HELP! My 1966 JD4020 diesel starts great, runs great while bush hogging for 20 to 30 minutes, then it gradually starts to bogg down and ultimately dies. Increased throttle with no RPM change. I changed the fuel filters hoping it might help in correcting the problem, which it did not. Also, I drained some fuel from the pit cock and it appears fine. My thoughts lean toward fuel starvation/restriction when reaching operating temp. I'm certainly an amateur that is humbly asking for help!

I assume you reference draining from the tank. That's good, but it does not guarantee the fitting there which which connects to the fuel line is not partially plugged. You could blow back through that line from near the lift pump. I don't know if a 4020 ever had a lift pump with a screen, but if there's a removable cap, that's a possibility. Then you could operate the lift pump by hand( again with line unhooked) to make sure you're getting good flow.

 

[JD Dave]

Sounds like the typical fuel starvation situation which will require a comprehensive check of all lines, transfer pump and filters and fuel supply to the injection pump. If all of that checks out, then there could be debris in the injection pump causing return pressure which can shut down fuel supply and proper high pressure supply to the injectors. This issue is common with older Roosa-Master pumps. May be time for a pump rebuild.

 

[Scott 730]

Sounds like the flex ring in the IP has left the chat and it's residual debris is plugging the return line.

 

[Client]

I will try that, and thank you.

I

I assume you reference draining from the tank. That's good, but it does not guarantee the fitting there which which connects to the fuel line is not partially plugged. You could blow back through that line from near the lift pump. I don't know if a 4020 ever had a lift pump with a screen, but if there's a removable cap, that's a possibility. Then you could operate the lift pump by hand( again with line unhooked) to make sure you're getting good flow.

I opened all the connections up to and including the feed to the injector pump and the flow was good at all three points; from tank to fuel pump, from fuel pump to the injector pump.

 

[Client]

Sounds like the typical fuel starvation situation which will require a comprehensive check of all lines, transfer pump and filters and fuel supply to the injection pump. If all of that checks out, then there could be debris in the injection pump causing return pressure which can shut down fuel supply and proper high pressure supply to the injectors. This issue is common with older Roosa-Master pumps. May be time for a pump rebuild.

I did check all the lines from tank to injector pump, all checked out. When I changed the fuel filters there were a lot of rust spec's. My worst fear is what you are identifying, a contaminated injector pump that also could have trashed the injectors. I suspect the rust is from the fuel tank. I have stabbed the injector before when I helped a retired JD mechanic put a kit in the engine. He has since passed away, so I will be looking for someone/somewhere to do their magic in Arkansas. This is the very reason I'm on this forum to gain knowledge and direction in hopes of keeping my deceased father's pride and joy going for the next generation.

 

[Client]

Sounds like the flex ring in the IP has left the chat and it's residual debris is plugging the return line.

You post and others suspect the injector pump. I replied in length my discovery of rust particles in the fuel filters that were changed. I've got to evaluate the fuel tank and find a remedy for the rust in addition to getting the injector pump evaluated.
Appreciate your input.

 

[JIM MN]

Time to do some trouble-shooting? Still have the old fuel filters? Cut them open, any rust and debris? If fairly clean, Ok. Do you know your way around the injector pump? If so, take off the timing window, two flat bade screw- driver screws, a small 1 1/2 inch long plate and rubber gasket. Fuel will come out, that is OK. Is there small black chunks coming out with the fuel? Leave window open, try starting the tractor. Will it start and run. If so, does the throttle respond to different speeds? Next step/

 

[Tx Jim]

Sounds like the flex ring in the IP has left the chat and it's residual debris is plugging the return line.

I agree on possible failing drive ring in inj pump. Simple test is loosen the 2 screws securing timing window cover on inj pump. If rubber gasket is stuck to pump housing pry it loose. With fuel leaking out does engine operate longer? If so drive ring is failing clogging check valve in fitting on inj pump that fuel return line attaches to. Inj pump needs to be disassembled for R&R of drive ring.

 

[Client]

Time to do some trouble-shooting? Still have the old fuel filters? Cut them open, any rust and debris? If fairly clean, Ok. Do you know your way around the injector pump? If so, take off the timing window, two flat bade screw- driver screws, a small 1 1/2 inch long plate and rubber gasket. Fuel will come out, that is OK. Is there small black chunks coming out with the fuel? Leave window open, try starting the tractor. Will it start and run. If so, does the throttle respond to different speeds? Next step/

I will T'shoot per your steps Sunday afternoon and post my findings. Appreciate the help!

 

[Client]

I agree on possible failing drive ring in inj pump. Simple test is loosen the 2 screws securing timing window cover on inj pump. If rubber gasket is stuck to pump housing pry it loose. With fuel leaking out does engine operate longer? If so drive ring is failing clogging check valve in fitting on inj pump that fuel return line attaches to. Inj pump needs to be disassembled for R&R of drive ring.

Will check it out Sunday afternoon and let you know. Are you saying start the engine after removal of the cover and gasket or before removal?

 

[JIM MN]

After removal of the cover and gasket. Fuel will run out but that is OK. Start the engine, will it run and respond to throttle change? If does, the injector pump governor retaining ring has fell apart, pieces plugging fuel outlet on the injector pump fuel return line. Injector pump will need to be removed and rebuilt. Suggest DIESEL TECH for help!

 

[Tx Jim]

Technically one doesn't need to remove timing cover just loosen screws & if stuck pry rubber seal from pump housing so fuel can leak out. When check valve is clogged in fitting pressure inside inj pump gets too high for IP to pump correctly.

 

[MSD]

Check the return line fitting on top of the IP. They get blocked not allowing return fuel.

 

[Tx Jim]

Check the return line fitting on top of the IP. They get blocked not allowing return fuel.

Slight correction return line fitting that contains check vale is on the upper side of 4020 inj pump not on the top.

 

[Client]

Tractor now fails to start. It has been starting and running for 20 minutes or so then gradually quits. I was going to check the gas cap venting and rule that out. Next, I'm going to remove the IP timing window plate and check for debris and try starting with plate off. Finger's crossed!

 

[Client]

After removal of the cover and gasket. Fuel will run out but that is OK. Start the engine, will it run and respond to throttle change? If does, the injector pump governor retaining ring has fell apart, pieces plugging fuel outlet on the injector pump fuel return line. Injector pump will need to be removed and rebuilt. Suggest DIESEL TECH for help!

Followed the stated steps, tractor fired right up and throttle responsive as designed. Can I drive the tractor with the window off so I can get it out of the field to the barn? I'm going to need a step by step guide for IP removal. I did this once in 2007 and remember that the flywheel had to be turned to a certain spot to keep everything in time. Right now I need to get it in the barn if that is a possibility?

 

[Client]

Technically one doesn't need to remove timing cover just loosen screws & if stuck pry rubber seal from pump housing so fuel can leak out. When check valve is clogged in fitting pressure inside inj pump gets too high for IP to pump correctly.

I removed IP window and she started right up. Jim MN says IP pump needs to be rebuilt. I need to know if I can drive it with the window off so I can get it out of the field and into the barn?