JD 4500 Tractor Help

[Mauser]

Hey guys, I was given a badly beaten up John Deere 4500 Utility Tractor last year. I have never owned a diesel engine and know nothing at all about them (but I am a pretty decent auto and motorcycle mechanic). I was able to get things working pretty well over the summer, but in the cold weather I am having some real problems getting it started.

Near as I can tell, I have relay issues, and when it won't start at all, I think the fuel shut-off solenoid is not activating (I hear weaker relay clicks when I turn the key on, but not the louder solenoid click I think I remember when things are working. Even when it does start, the safety interlock switches seems to be a problem. When the tractor is in neutral, it should both start and stay running without anyone in the seat (did that fine all summer long). But even in moderately cool temps, the engine will not start or stay running if I get out of the seat. And to make that issue even harder to troubleshoot, it starts working fine after I have been using the tractor for a while (even with temperatures below 20 degrees).

I found the owners manual on the JD site, but I do not have the service manual, so no schematic to look at or help locating specific parts. In the fuse panel I see:
K2 Start relay
K3 Fuel Shutoff relay
K4 Engine Run relay

Questions:
1. Is there a fuel shut-off solenoid in addition top the K3 relay, or would that be the same thing?
2. If there is a separate solenoid, where would it be?
3. Since a diesel engine does not use an electrical ignition to run, What is the K4 Engine Run Relay for?
4. Anybody know where I can find a schematic for this thing?

Thanks in advance for any help y'all might be able to give me!

 

[Deleted member 117362]

Hey guys, I was given a badly beaten up John Deere 4500 Utility Tractor last year. I have never owned a diesel engine and know nothing at all about them (but I am a pretty decent auto and motorcycle mechanic). I was able to get things working pretty well over the summer, but in the cold weather I am having some real problems getting it started.

Near as I can tell, I have relay issues, and when it won't start at all, I think the fuel shut-off solenoid is not activating (I hear weaker relay clicks when I turn the key on, but not the louder solenoid click I think I remember when things are working. Even when it does start, the safety interlock switches seems to be a problem. When the tractor is in neutral, it should both start and stay running without anyone in the seat (did that fine all summer long). But even in moderately cool temps, the engine will not start or stay running if I get out of the seat. And to make that issue even harder to troubleshoot, it starts working fine after I have been using the tractor for a while (even with temperatures below 20 degrees).

I found the owners manual on the JD site, but I do not have the service manual, so no schematic to look at or help locating specific parts. In the fuse panel I see:
K2 Start relay
K3 Fuel Shutoff relay
K4 Engine Run relay

Questions:
1. Is there a fuel shut-off solenoid in addition top the K3 relay, or would that be the same thing?
2. If there is a separate solenoid, where would it be?
3. Since a diesel engine does not use an electrical ignition to run, What is the K4 Engine Run Relay for?
4. Anybody know where I can find a schematic for this thing?

Thanks in advance for any help y'all might be able to give me!

Glow plugs all functioning? Compression good? Manuals are on ebay or pdf on line.

 

[Mauser]

To the best of my knowledge, this engine does not have glow plugs - it uses an intake manifold heater instead.

Temps here finally got a few degrees above freezing in the afternoon, so I got out and did some troubleshooting. I found the fuel shut-off solenoid on the injector manifold and verified it was getting 12V on the red wire when the key was turned on, but apparently not activating in the cold. I got out a heat gun and warmed it up a bit and it started working. The engine fires up instantly and runs perfectly as long as that dang thing activates! I guess I'll just have to replace it if I cannot clean it up inside to make it work reliably. Seems kind of strange that the solenoid has 3 wires going to it - can't figure that out until I find a schematic.

I'd still like to know what the Engine Run Relay does? Since there is a separate relay for the fuel shut-off solenoid, what possible other electric circuit could shut down a diesel engine? I do not see any visible injectors - just four metal fuel lines running from the injector manifold to the engine. I haven't really tried to examine it closely since I didn't have any problems with it running while the weather was nice!

 

[Deleted member 117362]

You are not heating your glow plugs before starting. 39hp Yanmar correct? Post a pic of dash and key also engine top.

 

[Deleted member 117362]

Yours may be older model like the 4020 and 2030 I have rebuilt for a friend with no glow plugs and he must use a block heater to start when cold, or crank forever. What year or serial number is yours and I will look at engine type.

 

[Mauser]

The engine is a Yanmar 2.0L, and the tractor was purchased new in 1999. The specs do state it is 39hp.

The operating manual is very specific in NOT referring to glow plugs. The section on starting in cold weather is titled:
"Starting in Cold Weather Using Intake Air Heater System", and it states "Tractor is equipped with an intake air heater system. An electric heating element warms the intake air."

The heater and connecting wires are clearly visible in the air intake tract, and it works perfectly - as long as the fuel shut-off solenoid is activated (and I activate the air heater for about 15 seconds as stated in the manual), this engine starts instantly, even in single digit temperatures. As I said, to the best of my knowledge, there are NO glow plugs in this engine.

The only time I have had to crank it extensively seems to be when the fuel shut-off solenoid has not activated correctly (based on my testing yesterday afternoon).