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Discussion Starter · #1 · (Edited)
We have a John Deere 5420, no cab, straddle mount I believe, that seemed to be at reduced power for a few weeks, then stalled in middle of the field last week. Barely got it started, but ran fine until finished, then it happened again next use. We’ve bled the system multiple times, changed all filters today, just in case and bled system again. Fuel tank near full.

No more bubbles or sputtering of air coming from either bleed screw, but tractor still won’t start. It cranks over and over and over, but won’t catch. Definitely a fuel issue it seems, but we are stumped and of course, NEED the tractor.

I‘m aware these models have a gravity feed fuel system and that JD has a bulletin recommending installing an electric fuel pump, but for now, I am looking for a solution to getting the tractor started and running consistent. We’ve had the tractor 15+ years, light to medium use, always stored inside, never had this issue before. Any help or ideas would be GREATLY appreciated!

Ive found our owner’s manual to be nearly useless most of the time. For example, it lists two different fuse box configurations for the 5X20 models, neither one matches our tractor, so if possible, when advising, can you please indicate where we should be looking for the part you are indicating if it’s not an obvious location.
 

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Have you checked for 12 volts being supplied to injection pump when the key is turned on? If no voltage there, check your fuses. If there is a blown fuse, then most likely cause is the cold start temp sensor that is located in the thermostat housing. Unplug the sensor to keep fuse from blowing. If that works, then replace sensor. Tractor will run without the sensor hooked up.
 

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Welcome to MTF
I'll bet there's is air in the fuel system between tank & injectors. Have you loosened inj lines at injectors & attempted to start looking for bubbles of air? I suggest to check for good fuel flow from fuel tank to inj pump. Is fuel tank venting IE allowing air to enter tank as fuel is trying to exit tank? Try operating engine with a shop towel instead of cap covering tank filler neck.
 

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Discussion Starter · #4 ·
Welcome to MTF
I'll bet there's is air in the fuel system between tank & injectors. Have you loosened inj lines at injectors & attempted to start looking for bubbles of air? I suggest to check for good fuel flow from fuel tank to inj pump. Is fuel tank venting IE allowing air to enter tank as fuel is trying to exit tank? Try operating engine with a shop towel instead of cap covering tank filler neck.
That’s Tim! We did try that yesterday to no avail. Appreciate the suggestion though!
 

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Discussion Starter · #5 ·
So
Have you checked for 12 volts being supplied to injection pump when the key is turned on? If no voltage there, check your fuses. If there is a blown fuse, then most likely cause is the cold start temp sensor that is located in the thermostat housing. Unplug the sensor to keep fuse from blowing. If that works, then replace sensor. Tractor will run without the sensor hooked up.
I’ve read a lot about this problem and looked into it somewhat yesterday. Part of the trouble is that the owners manual we have, even though for our model shows two fuse box layouts, neither fit our tractor :mad: so I can’t even tell which fuse is the right one. Guess I could just pull all fuses one at a time to check that way, which doesn’t sound like a lot of fun, but doable.

Second question about that. I know it will run without sensor, but do I just unplug the sensor and leave each end as a disconnect in the interim! The wiring on our tractor doesn’t allow for the sensor wire to be removed, then connect existing ends together. I’m guessing this circuit needs to be complete before it can work?

Thanks so much for your time!
 

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Discussion Starter · #6 ·
Also, the bleed screw on the injector pump has a stupid degrading washer on it, that is now non-existent, so creating a new problem. I searched the net for 2 hours yesterday looking for a replacement washer or even the screw itself assuming it would come with a new washer. No glory. Suggestions?
 

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Also, the bleed screw on the injector pump has a stupid degrading washer on it, that is now non-existent, so creating a new problem. I searched the net for 2 hours yesterday looking for a replacement washer or even the screw itself assuming it would come with a new washer. No glory. Suggestions?
How about using a small O ring that fits tight or a copper washer, parts stores usually have the washers.

I know you said you bled the injectors and the way I found works the best is to open all the nuts and crank it over and then tighten each nut as the fuel starts coming out.

When you replaced the filter did you dump the contents of it out into a clean container to see if there was water in it? That's always a good habit to get into when changing fuel filters will give you a heads up if there could be a water or rust problem plugging the filter.
 

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So

Second question about that. I know it will run without sensor, but do I just unplug the sensor and leave each end as a disconnect in the interim! The wiring on our tractor doesn’t allow for the sensor wire to be removed, then connect existing ends together. I’m guessing this circuit needs to be complete before it can work?

Thanks so much for your time!
Leave both ends disconnected. Don't try to "jump" across the terminals. The wire that sends 12 volts to injection pump shut off solenoid is still complete with sensor unhooked. Do you have a test light or volt meter to check for voltage?
 

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Discussion Starter · #9 ·
Leave both ends disconnected. Don't try to "jump" across the terminals. The wire that sends 12 volts to injection pump shut off solenoid is still complete with sensor unhooked. Do you have a test light or volt meter to check for voltage?
so my husband had a friend come help yesterday. They tested everything with a voltage meter as well as checking all of the fuses since the diagram in our manual is incorrect. He has also talked with both of our local John Deere dealers, no help from either place. Looking for a field mechanic to come work on it. Thanks every for your input!!!
 
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