Help with Ford 3930...no crank

[Jason280]

I've had a early/mid-90's Ford 3930 for years, and never had any issues with the tractor...until several months back. Went through multiple episodes of sluggish acceleration/low power, ultimately figured out I had algae growing in the diesel (clogging the fuel petcock and injector pump inlet screen). I cleaned the tanks/filters/lines, added and cycled through biocide, and *think* I have that issue sorted.

I've gotten in the habit of cranking/running it every couple weeks, just to be sure the fuel is getting cycled around (and isn't sitting too long). Hopped on it a few days ago to crank, nothing. Starter doesn't move, no noise, nothing. I can hear a slight "click", but that's it.....lights all illuminate on the dash, and headlights come on when switched.

The neutral safety switch on the high/neutral/low shifter has been fickle before in the past, and occasionally would require a little "jiggling" to get it to crank. This time, no amount of jiggling made any difference. So, I went ahead and bypassed the neutral safety switch...no change. Checked voltage at the battery, it's showing 12.4-12.5v (battery is less than 1 year old). Just in case, hooked a jump pack in place, still nothing.

Not sure how to proceed from here. It really *seems* like some sort of safety switch is preventing any cranking to proceed. I know it has a PTO safety switch, not sure about a seat switch. I guess I could try jumping the starter solenoid, but that's not anything I've ever had to do before. It's likely something simple, just need some ideas on troubleshooting before I get back to it tomorrow.

 

[TractorTech]

I was going to ask if you checked/bypassed the PTO switch. Jumping at the starter would be the first thing to do after inspecting the PTO switch for obvious problems as it will tell you if the starter and solenoid are functioning.

 

[Jason280]

What's odd, its doing the exact same thing as before (with regards to the neutral safety switch)...its just jiggling (or bypassing the switch all together) now does nothing.

 

[Roadworthy]

A good starting point is monitoring the battery voltage when attempting to engage the starter. If it stays at the same point you have something keeping the starter from engaging. If it drops significantly - say below ten or so - the battery may have issues. Have it load tested. In any case clean the battery terminals well as well as the insides of the cable connectors. Examine the cable connections for signs of corrosion which can impede current flow. Replace connectors onto the battery and tighten securely. If you can move them they're not secure. Follow your ground lead to the frame connection. Clean and tighten there, too. Now you're ready to begin troubleshooting, or you may have already fixed the problem.

 

[Jason280]

Here's what I've been able to check so far...

Battery reads 12.34v with no load. Not ideal, but should be enough to at least engage the starter.

I tried a different jump pack, and was getting 15+ volts to the battery...which dropped to 14.8 or so with the key engaged. I did a load test on the battery, and it reads "good".

Looking at the starter, I'm not even sure how you even begin to jump start/override the solenoid.

As far as the "clicking" noise, I've isolated it to a relay near the battery. Not exactly sure what it does, but you can hear/feel it "click" when the key is turned....but still no starter involvement, just the "click".

Backing up a little to the neutral safety switch, it simply consists of two wires that feed through a grommet in the top of the shifter housing and connect to the switch inside. If my understanding is correct, the switch remains "open" until in the center position (neutral), which closes the switch. To bypass this, I've simply cut the two wires behind the dash, and closed the connection with a wire nut. Next guess would be the PTO safety switch, which will require bypassing as well.

Other than that, I am not sure how to proceed.

eta: I'm considering putting the battery on a charger anyway, but doubtful it will make any difference.

 

[TractorTech]

Looking at the top of the starter, you have to remove the nut on the post holding the plastic safety cover over the solenoid. Once the front of the solenoid is exposed, you will see that there is a small lead, usually on a spade tab. That is what gets energized when the key is switched to start and all neutral switches are satisfied. Make sure the transmission is in neutral, take a jumper wire, from the positive post of the battery and touch it to the spade connector on top of the starter solenoid on top of the starter. If it turns over, then the starter and solenoid are good. Start looking up the line at the PTO switch or, possible the relay that you posted in the picture. Bypassing them until you find the culprit.

Also, your description of the neutral switch in the transmission in correct.

 

[Semper Paratus]

My 3930 in 6 years has been through two PTO safety switches. They are not particularly easy to jumper out without 5 -10 minutes of disassembly. When mounted the switch pinches the weather boot between the switch and the transmission body.

 

[ROUSTABOUT]

I've had a early/mid-90's Ford 3930 for years, and never had any issues with the tractor...until several months back. Went through multiple episodes of sluggish acceleration/low power, ultimately figured out I had algae growing in the diesel (clogging the fuel petcock and injector pump inlet screen). I cleaned the tanks/filters/lines, added and cycled through biocide, and *think* I have that issue sorted.

I've gotten in the habit of cranking/running it every couple weeks, just to be sure the fuel is getting cycled around (and isn't sitting too long). Hopped on it a few days ago to crank, nothing. Starter doesn't move, no noise, nothing. I can hear a slight "click", but that's it.....lights all illuminate on the dash, and headlights come on when switched.

The neutral safety switch on the high/neutral/low shifter has been fickle before in the past, and occasionally would require a little "jiggling" to get it to crank. This time, no amount of jiggling made any difference. So, I went ahead and bypassed the neutral safety switch...no change. Checked voltage at the battery, it's showing 12.4-12.5v (battery is less than 1 year old). Just in case, hooked a jump pack in place, still nothing.

Not sure how to proceed from here. It really *seems* like some sort of safety switch is preventing any cranking to proceed. I know it has a PTO safety switch, not sure about a seat switch. I guess I could try jumping the starter solenoid, but that's not anything I've ever had to do before. It's likely something simple, just need some ideas on troubleshooting before I get back to it tomorrow.

I've dealt with that. It was a crystallized end of a battery cable. Where the lead is molded on the wire.

 

[blehmann]

Multiple times in my life on multiple vehicles having the same problem. It has almost always been the ground cable corroded where it bolts to the frame. Pull it off. Sandpaper the terminal and the area on the frame around the bolt hole.

 

[Jason280]

7/30 Update

Finally had a chance to play around with the tractor again. I pulled the input(?) wire off the starter solenoid, and tested the connector...I get 11.9v with the key switched to the "CRANK" position. Seems like it would be enough voltage to close the solenoid, but not 100% sure. I tried to use my Power Probe to apply 12v to the ignition input on the solenoid, but simply can't reach it...the post itself is recessed enough that I can't get to it with the probe extension, and its pretty well blocked by the filter housing. So, on the plan B. I used a 8ga wire, and jumped the solenoid terminals....turned right over and cranked without issue.

Good news is, tractor ran great. Doesn't *seem* to be any fuel related issues that I can tell, so maybe the biocide killed all the growth. I'm assuming the starter solenoid is bad, so I'll look into finding a replacement today.