Ford 4630 fuel solenoid issues

dkocian

New User
I have a Turbo Diesel Ford 4630 that is "emissioned", which means it was one of the last they built. Different injection pump and fuel filter setup, although it uses same fuel solenoid as earlier 4630's. First it would not start and I figured out the solenoid was bad. Replaced it, and started fine (after priming it) but then would not shut off with key. Kept running. Had to turn off fuel at the tank, which meant it lost prime again. Replaced the solenoid again and it did the same thing. Now, it won't start again.
I figured out that the relay puts voltage to the solenoid when key is turned on, but when you turn the starter, the voltage at the solenoid drops to zero. Thought it was the relay, but I pulled it and tested it and it works fine. Tested it with resistance measurement but then put a load on it and it still worked fine. However, voltage at the solenoid still drops to zero when the starter is running.
I can't find a wiring diagram on this machine. Have seen several and have the IT shop manual (worthless for the emissioned tractor) and the New Holland Operator's manual (also almost worthless for this tractor). No wiring diagram. Found several through this forum and I gather there is a diode that may be causing the problem but don't know where it is or what it looks like.
Dealer finally told me how to shut down the tractor without turning off the fuel. Just put it in high gear, with throttle down as low as possible, and gradually let off the clutch. Tractor will bog down and die. Sure saves priming the darn thing every time.
Still no idea why it would not shut down, but first thing first, I have to get it to running. I guess running a wire direct from the battery to the solenoid would keep it open, but would like to fix it right.
 
Is the tractor new to you and has had the problem since you've had it, or did it work properly at some point and just started having the problem?

I'm not familiar with that model, but it sounds like it needs some sort of bypass circuit to provide power to the solenoid when the key is in the start position, or maybe the key switch itself should provide that power but it's either bad or the wrong key switch.
 

If you disconnect the wire from the fuel solenoid will the engine stop running?
I've only messed with one of the emissionized tractors (3930), it has a completely different fuse box and wiring from the 94 3930 wiring I have.
My 6 volume set of Series 10, 30 service manuals don't cover the emissionized models, they made a 7 volume set with 2 volumes of electrical that probably cover your tractor.
 
If the voltage drops to zero when cranking, it sounds to me like you have an incorrect or more likely a miswired keyswitch. I
don't have wiring diagram for that one.

As for shutdown, the top of the pump should have a lever on it that will allow you to shut it off as if it had a kill cable on
it.
 
(quoted from post at 23:36:32 11/20/18) Is the tractor new to you and has had the problem since you've had it, or did it work properly at some point and just started having the problem?

I'm not familiar with that model, but it sounds like it needs some sort of bypass circuit to provide power to the solenoid when the key is in the start position, or maybe the key switch itself should provide that power but it's either bad or the wrong key switch.
Not new to me. I have owned it for over 5 years. Had a problem before but had the dealer fix it. They just replaced the solenoid.

One of the wiring diagrams shows a bypass, but it goes through the relay and then to some diodes. However, another diagram shows the diodes are actually part of the relay. I was hoping someone had seen one of these before and knew what I should look for. I'll just back trace through the wiring but it is all bundled and hard to follow.
 
It used to stop running if I disconnected the wire from the solenoid. Now, it does not, but solenoid appears to work fine off the tractor. That has me concerned, but I am now thinking it may be totally separate from the non-starting problem. Could just be crud in the line blocking the solenoid from closing the hole. I am going to clean it out and check tomorrow.
Wish I had the 7 volume set of manuals. Maybe they would cover it. I don't have, but have seen, the volumes you have. They did not address the emissioned version.
 
Key switch worked for years, so I doubt a miswire. Thought about defective switch, but can't tell without following out the wiring. Switch puts power to the solenoid when turned on, but something is cutting the power when switch goes to start. That means the relay is working properly (which I believe means the switch is working properly) but something is interfering with current to the relay. At least that is my guess.
Regretfully, this newer fuel injector pump does not have the switch on the top. Checked with the dealer and they confirmed it. The old model had a primer pump. This one does not. The old model had a manual cutoff switch. This one does not. Progress!
 
There?s a supplement to the 10 and 30 series set that is included in the later versions. Part 14 if I remember correctly. Covers the electrical stuff
on the emissionized tractors and other late changes to the models covered. Used to be able to buy individual volumes of the service manuals
but I have noticed they seem offer only the whole thing now.
 
I've been through this before, took me a little while to figure out it was the diode, it's a Lucas in-line diode that has a spade connector, and literally, looks like some kind of connector with no purpose, but it is a diode. I ran a jumper to the solenoid and could hear it click and knew that it would run after that. There is a wiring diagram in the 6 volume OEM shop manuals, and it is a little confusing. There is a part number in the parts diagrams on the CNH website. Darned mice like to build nests behind the instrument cluster and one time they chewed a wire, the one to the fuel solenoid. I believe that it shorted and took out the diode, as I parked the tractor, shut it off, and it would not start later.

Part Number is 83929594

Photo is of a similar diode by Lucas

cvphoto3185.jpg
 
So this diode is located behind the instrument cluster? Do you happen to know in which circuit this diode this diode appears and just what is it's function?
I have run across similar problems on some 10 and 30 series tractors where the signal to the shut off solenoid goes dead while cranking and have never been able to figure out why. I've never seen the wiring diagram supplement RickB mentioned and didn't know about the diode. I usually end up adding an alternative temporary signal to work around it.
 
The hard copy 10 and 30 service manual in my (new) employer?s service library does not have the supplement. The dealer I used to work at in
NY had it in a replacement set they purchased. The current version NH has online as a download has it.
 
Yes, right behind the instrument cluster in the wiring harness. It is shown on the CNH parts section of their website and the part number I listed is current. They ordered mine for me. I am not sure if there is a generic equivalent. Going from memory, my 6 volume set is in a box right now, I do recall seeing a diode somewhere in the wiring diagram, or one I found on the web after doing a search. That tipped me off there was one in the circuit and that was likely the problem. I was using the multi-meter often when trying to figure this one out as I had to repair this circuit. I made a jumper wire so I could move the tractor.

The problem you describe could also be the connection at the solenoid, I noticed this is or can be a not so tight connection.
All of this should be basic wiring, connections and such, but sure had me stumped for a bit. Kind of an obscure problem with these, but having dealt with it, kind of glad so as to share with other owners being a simple fix that might have you on a wild goose chase for a bit.
 
mvphoto27081.jpg

I found this diagram for the 3930 and I thought it was the same or close for the 4630. On this site, there is another series of posts where a different diagram was posted and it shows different wiring for the 4630. Can't find that diagram but will keep searching. Still have not figured out the purpose of the diodes unless it has to do with the start safety switch.[/img]
 
I think the way it works is that the top wire on the schematic is the only "hot" wire that will turn on the solenoid. The relay is activated by either of the bottom two wires, each of which has a diode in the circuit. One is obvious and runs directly to the ignition terminal on the switch. That activates the solenoid when the switch is turned on and keeps the solenoid open while the tractor is running, after it starts and the switch returns to ign. The third line also can turn on the relay, and it also has a diode, but it runs back through a lot of the regular lights and gauges. I would have thought this one would be tied into the start position on the ignition switch, but I cannot see that route. The only purpose I can see for the diodes is to make sure current does not flow into the relay except when a particular line is activated and also so the current does not flow into the other of the two circuits.
I just don't see the start position on the ignition switch hooking up to the relay.
Of course, as I said, this is not the exact wiring diagram for the 4630 so there may be a difference that could be major.
 

I've been studying the diagram you posted for some time, and even blown up to 200% I can barely make out but a few of the printed descriptions of the various components pictured. I don't recall finding this diagram in any of the books I've seen or currently have. I wonder if you might be willing to Email a copy to me? I can hope it may come through with a bit more clarity.
 
I actually found that diagram online at the following link:
https://www.tractorbynet.com/forums/files/owning-operating/279889d1347120811-ford-newholland-3930-wiring-ford-newholland-3930-wiring-diagram
 

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