G5200 Fuel System Operation. . .

[WayneM]

I'm working to get a family member's G5200 HST back operating. The final problem is with the fuel system and I was slowed down because it appears a couple years ago an authorized Kubota dealer sold my family member a bad electric fuel pump. Or at least now it is bad. I will have a new one in hand soon.

FYI, I have already bled the lines, replaced the in-line filter by the electric pump, and had to replace the block-mounted filter canister with a brand new Kubota unit because the bleeder screws had been damaged and would not seal down properly.

I'm not familiar with any diesel fuel system design and I don't have a service manual. My question is if the G5200 uses what I would call a recirculating fuel system.

So if someone familiar with the G5200 setup I would greatly appreciate knowing the following:

1. Does the electric fuel pump, back behind the right rear wheel, continuously pump and circulate fuel? Is fuel not used returned to the fuel tank?

2. Is there any sort of mechanical fuel pump on the engine block itself?

3. Is pressure supposed to be maintained in the fuel lines?

4. Should the electric fuel pump begin pumping and making a sound when the ignition key is turned on? For a while with the key on, but the engine not started, I heard a "puckita-puckita" faint sound coming from that fuel pump. When I pulled off the hose I had diesel being pumped out.

Any help greatly appreciated. Thank you in advance.

 

[North Idaho Wolfman]

No it is not a recirculating system, fuel is pumped to the Injection pump which them pressurizes it and any fuel not used in the injection process by the injector is returned to the tank.

 

[BruceP]

I'm working to get a family member's G5200 HST back operating. The final problem is with the fuel system and I was slowed down because it appears a couple years ago an authorized Kubota dealer sold my family member a bad electric fuel pump. Or at least now it is bad. I will have a new one in hand soon.

FYI, I have already bled the lines, replaced the in-line filter by the electric pump, and had to replace the block-mounted filter canister with a brand new Kubota unit because the bleeder screws had been damaged and would not seal down properly.

I'm not familiar with any diesel fuel system design and I don't have a service manual. My question is if the G5200 uses what I would call a recirculating fuel system.

So if someone familiar with the G5200 setup I would greatly appreciate knowing the following:

1. Does the electric fuel pump, back behind the right rear wheel, continuously pump and circulate fuel? Is fuel not used returned to the fuel tank?

2. Is there any sort of mechanical fuel pump on the engine block itself?

3. Is pressure supposed to be maintained in the fuel lines?

4. Should the electric fuel pump begin pumping and making a sound when the ignition key is turned on? For a while with the key on, but the engine not started, I heard a "puckita-puckita" faint sound coming from that fuel pump. When I pulled off the hose I had diesel being pumped out.

Any help greatly appreciated. Thank you in advance.

I have a G5200 with the D600 engine.

ANSWERS:

1) Yes - the electric pump CONTINUOUSLY pumps fuel thru a loop from tank, to engine-mounted-injection-pump, back into tank. You can hear it 'clicking' while it is running.

2)Yes, the engine OFF knob is connected directly to engine-mounted-injection-pump. It has three steel (High Pressure) fuel lines each which lead to one cylinder.

3)There is very little "pressure" in the fuel lines within this loop. It is intended to keep constant fuel supplied to the engine-mounted-injection-pump. Also, the fuel is repeatedly circulated through both filters so it gets cleaner and cleaner as it moves through the loop.

4) I answered this with #1 above... YES... the electric pump runs continuously while the key is on.

--------------------
For your engine to start you need THREE things
1) HEAT (glowplugs)
2) COMPRESSION (fast cranking from starter)
3) FUEL (break free each of the three fuel lines at cylinder and make sure fuel is squirting out whilst cranking)

If the glow-plugs are not glowing.... all the cranking in the world will not start that D600 engine! (An unglowed D600 might do a lot of smoking out the exhaust whilst cranking)

Hence, make CERTAIN you are turning the key LEFT for at least 40 seconds to preheat the glowplugs BEFORE attempting to start the engine. Below 40F.... glow for up to a full 60 seconds. The glow indicator on the dashboard should become orange about 20 seconds into a glow-session. Do not glow a hot engine.

You can use voltmeter to test that there is 9-11 volts on the top of all three glowplugs while the key is turned LEFT.

If you are getting voltage... this is only the FIRST step to test the health of the glowplugs. You also need to remove the jumper-wire from the top of the glowplugs and measure OHMS from the top of each glowplug to engine-block. Any glowplug which measures open-circuit is bad.

 

[North Idaho Wolfman]

I guess I stand corrected.
In my defense that is the only model I know of that works that way.

 

[whitetiger]

I guess I stand corrected.
In my defense that is the only model I know of that works that way.

Also BX, ZD, G series, F series, SVL, KX and all Teir 3 and 4 engines

 

[D2Cat]

Hey Bruce, you also need an air supply, or those other 3 won't matter!!

 

[WayneM]

Thanks!

Thanks to everyone who chimed in. I thought I had set it up so I would get an email if anyone replied to my post. Now that I'm over 800 miles from where the G5200 is, I finally checked back. Thanks especially to BruceP whose clear and detailed answers confirmed what I thought was going on.

Thanks for all the help. I'll share the story of what ended up getting done, ending up in the successful refurbishing of a G5200 that had sat out in the open East Texas weather for 5 years and then another 2 years under cover but still outside.

The G5200 had been sitting since 2010 when the replacement of a cantankerous original Kubota fuel pump didn't get it going. I don't remember if I mentioned that a half dozen sections of hose had big holes made by rats with too much time on their hands. I did check all the fluids, it is an HST model, the radiator, oil, coolant and all things were fine there. I did decide to replace the battery even though the current one would turn the engine over pretty well. The tractor had fastidious maintenance records and a little over 1800 hours on it.

So. . .I kept working on the tractor finally deciding to take a chance on a fuel pump I tracked down on Amazon. Under $20 delivered. I found one that looked precisely like the replacement sold by a Kubota dealer in East Texas. That fuel pump box had all the Kubota labels, part numbers on it etc. Seemed unlikely, but I later confirmed that the Kubota dealer's fuel pump was DOA. They had't checked it. I would take it back but this is rural Texas, a long trip, and it had been purchased 7 years ago! Being an electricity guy I also checked all the ground connections throughout the machine. Pulled apart connectors, cleaned, reinserted and pulled apart several times to wipe the contacts. Removed all battery cables, cleaned and reseated wires as well as pulling off/unbolting all grounds, cleaning and reseating.

The fuel pump via Amazon (some seller in California) arrived but it still took me several days to get it to work. First the connector on the pump was a different snaplock type. No problem, I design and build all sorts of electronics and electrical stuff so had shipped my digital volt meter, a soldering iron, and heat shrink tubing ahead of time. Did a professional job of replacing the connector BUT there was no documentation so I began by hoping the wire colors (BLACK and BLACK with white stripe) would be the same. The little box on top of the new pump contains some electronic components (an integrated circuit and other parts) so I was not about to willy-nilly try reversing the wire polarity when the pump failed to work and was getting good 12 volt DC. Finally, using a current meter test, I was able to determine that it seemed the replacement pump wire colors were reversed. I did a quick off tractor test with a regulated DC supply and the pump ends capped. BINGO the pump kicked off! So I rewired and labeled the wires on the pump, reconnected it, and, as they say somewhere "Bob's Yur Uncle!"

Then was time for a complete lube/grease job, belt check (it has the 48" three blade mower deck) and check over. It's now got 4-6 hours on it with regular checks and it running like a demon. . .or rather "Like a Kubota."

As an electronics guy with little prior mechanical and NO diesel engine experience I think this the project I am most proud of finally getting done.

I asked my sister (the owner) if I should spiff up the paint and we both agreed that is has aged gracefully, and then been brought back to life after a long sleep. It deserves to show the fact that it is a worker not a "Trailer Queen."

Thanks to all those who helped!

 

[WayneM]

Thanks to everyone who chimed in. I thought I had set it up so I would get an email if anyone replied to my post. Now that I'm over 800 miles from where the G5200 is, I finally checked back. Thanks especially to BruceP whose clear and detailed answers confirmed what I thought was going on.

Thanks for all the help. I'll share the story of what ended up getting done, resulting in the successful refurbishing of a G5200 that had sat out in the open East Texas weather for 5 years and then another 2 years under cover but still outside.

The G5200 had been sitting since 2010 when the replacement of a cantankerous original Kubota fuel pump didn't get it going. I don't remember if I mentioned that a half dozen sections of hose had big holes made by rats with too much time on their hands. I did check all the fluids, it is an HST model, the radiator, oil, coolant and all things were fine there. I did decide to replace the battery even though the current one would turn the engine over pretty well. The tractor had fastidious maintenance records and a little over 1800 hours on it .

So. . .I kept working on the tractor finally deciding to take a chance on a fuel pump I tracked down on Amazon. Under $20 delivered. I found one that looked precisely like the replacement sold by a Kubota dealer in East Texas. That fuel pump box had all the Kubota labels, part numbers on it etc. Seemed unlikely, but I later confirmed that the Kubota dealer's fuel pump was DOA. They had't checked it. I would take it back but this is rural Texas, a long trip, and it had been purchased 7 years ago! Being an electricity guy I also checked all the ground connections throughout the machine. Pulled apart connectors, cleaned, reinserted and pulled apart several times to wipe the contacts. Removed all battery cables, cleaned and reseated wires as well as pulling off/unbolting all grounds, cleaning and reseating.

The fuel pump via Amazon (some seller in California) arrived but it still took me several days to get it to work. First the connector on the pump was a different snaplock type. No problem, I design and build all sorts of electronics and electrical stuff so had shipped my digital volt meter, a soldering iron, and heat shrink tubing ahead of time. Did a professional job of replacing the connector BUT there was no documentation so I began by hoping the wire colors (BLACK and BLACK with white stripe) would be the same. The little box on top of the new pump contains some electronic components (an integrated circuit and other parts) so I was not about to willy-nilly try reversing the wire polarity when the pump failed to work and was getting good 12 volt DC. Finally, using a current meter test, I was able to determine that it seemed the replacement pump wire colors were reversed. I did a quick off tractor test with a regulated DC supply and the pump ends capped. BINGO the pump kicked off! So I rewired and labeled the wires on the pump, reconnected it, and, as they say somewhere "Bob's Yur Uncle!"

Then was time for a complete lube/grease job, belt check (it has the 48" three blade mower deck) and check over. It's now got 4-6 hours on it with regular checks and it running like a demon. . .or rather "Like a Kubota."

As an electronics guy with little prior mechanical and NO diesel engine experience I think this the project I am most proud of finally getting done.

I asked my sister (the owner) if I should spiff up the paint and we both agreed that is has aged gracefully, and then been brought back to life after a long sleep. It deserves to show the fact that it is a worker not a "Trailer Queen."

Thanks to all those who helped!