John Deere 4020 Won't Run

Hello everyone,

I have a 1964 John Deere 4020 that I picked up and was told it needed a new fuel injection pump. I was able to get the tractor to start on the old injection pump and it ran for about a minute and then died and would not restart. I changed the fuel filter and installed a new fuel injection pump, bled the injection lines and then it started and ran for about 2-3 minutes before it died again and will not restart. I pulled the upper injection line off and blew air through all of it, and nothing came out. I then blew air through the return line into the fuel tank and nothing was clogged in there either. I then tried to get it to start on starting fluid and it would not start(after hooking everything back up and bleeding the lines). There is fuel getting to the injectors when I loosen the banjo bolts.

Any ideas or guidance would be greatly appreciated. Thanks in advance!

Look at the return line at the pump I believe it has a fitting with a bead like ball in there it may be the problem they break up and plug the fittin so the return fuel can't get back to the tank causing a back pressure so they stop till the pressure equalizes then go again.

There possibility is the flex ring broke.

I am wondering why it wouldn't start on starting fluid. . . a healthy engine should start and run on starting fluid no matter what is going on with the fuel
system.

Hello caseitman welcome to YT! You have given no
indication of the amount of fuel you get out of the line
from the tank. That tractor also has a fuel supply pump
that originally had a sediment strainer on top. I believe
in many replacement pumps that was eliminated.
Bottom line is you give no indication of what type of
flow that pump is providing. It could be inoperative, it
may have failed in a way that introduces air into the
fuel stream. This problem may be hidden by the fact
that the supply pump is leaking fuel into the crankcase
through its mounting area to the engine. The injection
pump has the ability to draw fuel to itself but these
systems are designed to supply the pump, rather than
the pump drawing fuel through the filters. You mention
opening the banjo bolts on the injection lines at the
pump I suppose you know to properly bleed the
injector lines you need to loosen the lines at the
injectors.
Catguy is not real clear in his description of the
problem he has mentioned, bottom line is if you
actually have a newly rebuild injection pump this
should not be your problem. If you did for some reason
use the return line fitting out of the old pump it could
be a problem. Governor weight flex ring deterioration
is a problem in Roosamaster IJ pumps. After time, heat
age and exposure to fuel they become brittle and start
breaking apart. The link shows an example of one
being installed. The pieces of the ring float out and
plug the return check valve fitting. When this happens
the housing pressure rises and then the main high
pressure fuel plungers cannot pump fuel. The
diagnosis check for this is to loosen the two screws of
the timing window cover just enough to relieve the
pressure in the housing and the engine should return
to normal. Also usually when the engine dies due to
this problem the housing pressure drops and the
engine will restart but then the RPMs slow as the
pressure builds up again. This is where part of what
cat guy mentioned comes into play. As a ..cheat fix..
the check ball can be knock out of the fitting which
allows the pieces to just flow out into the return. The
engine will then run somewhat normally depending
where other pieces of the ring may go in the pump to
affect the operation of other mechanisms. As I said a
newly rebuilt pump using the return check fitting
supplied with it should have no issues like this.
However, if the pump was rebuilt a couple years ago
and has been setting who knows, I am only saying this
in case the pump came with the tractor. I do agree with
the fact that the engine should fire on starting fluid
unless you are not using enough.
Roosamaster IJ pump example flex ring

trace the fuel line from the tank to the fuel TRANSFER PUNP if
its had a rubber hose splice remove check LOOK BLOW AIR in it
then replace the rubber hose. while lie is off check fuel flow. cant
remember but seems ilke roosa master likes steady bubble free 3
gallon per minure flow. time the flow in a bucket. if you get set
right a gallon is nuff to determine flow by time.
i bought a slick low hour 4010 that acted simular. as soon as i got
it home i found rubber line under tank going to frame area. it
had a flapper tore out of hose where it hit sharp edge of fuel line
where it was cut. smoothed the steel line down and slid new hose
on n it ran trouble free for years till my ex got it

Loosen the timing window so fuel can drain out,, leave it loose and see if it will stay running..if it does the return fittting is clogged..

Used red: I'm glad you put that in better perspective than I did. I could remember the problem just didn't recall which it was the ball or the flex ring till I had already sent it. Thankyou.

Welcome to this forum
I personally only use starter fluid as a very last resort. I've witnessed other people keeping engine operating by continually spraying starting fluid into intake BUT that will never transpire on a tractor under my supervision. Many piston top ring lands & rings have been broken from inappropriate use of starting fluid.

Do you have inj pump timed correctly? What compared to TDC? Do you have good fuel flow from tank to inj pump? Is fuel tank venting? If this tractor has Syncro-range trans & a helper was available then I would put trans in a higher gear & attempt to tow start the engine

I believe we had a little misquoted or miscalculated number for the required flow for the injection pump on a 4020. What I see on the NE test about the max fuel use in ..gallons per hour.. (GPH) is 6 plus something lets just call it 7 per hour. A pint of flow per minute at 8 pints to a gallon calculates to 7.5 gallons per hour. You do need to add in some extra flow for pump and injector return but I believe that is only a small percentage of the GPH used by the engine. One gallon per minute is 60 GPH, the 3 gallons per minute suggested is 180 GPH, I am not even sure if black smoke rolling tractor pullers use that much. In my opinion if he can produce a pint a minute or to be safe a pint and a half a minute he should have plenty of fuel flow. Carbureted cars used to have a required pumping spec out of the fuel pump by cranking the engine with the starter a certain length of time. I do not know if a 4020 repair manual contains such a spec.

Thank you everyone for the insights and recommendations. Go figure with my luck... I loosened the timing cover on the injection pump last night and then retightened it and let it sit overnight. Went out this morning and with a quick squirt of starting fluid it started right up and ran fine. I'm not 100% sure what changed, but maybe there was a slight air bubble somewhere and it disappeared overnight. Hopefully everything is fixed now and it should run fine.

It does have a very hard time starting now, and doesn't seem to want to start without starting fluid. Any suggestions or ways to resolve this?

Thank you again for all of your knowledge and recommendations!

This post was edited by caseitman on 05/16/2023 at 12:05 pm.