790 Sporadic Starting

[Industrial Toys]

I had a 770 (same machine) and never had a lick of trouble. Except a terrible algie in the tank and filter issue and once had an issue with this timer for the fuel solenoid. I was surprised to find that circuit board quite hidden, I believe just beside the instrument panel and found a blown fuse. Replaced it, and never had another problem nor did the subsequent owner.

 

[sriddle1]

once had an issue with this timer for the fuel solenoid. I was surprised to find that circuit board quite hidden, I believe just beside the instrument panel and found a blown fuse. Replaced it, and never had another problem nor did the subsequent owner.

Industrial Toys, thanks for the post..........you wrote, "found a blown fuse", was that around or a part of the timer/Delay Module, I'd want to look at that first, the more simple the fix the better.........

Dieselcrawler, Took a look this morning and found I can maneuver around the 419FEL, even loosened the back retaining bolt but have to take a quick trip to get a 10mm long socket for the front bolt. Couple of questions please:

• I noticed a gasket, will that be an issue once I remove the solenoid, does it need to be replaced.
• I'm not too keen placing the ignition switch into start position with the unit out, can I remove/unplug the solenoid and do some bench test using 12volts, pehaps using battery jumper cables with nails clamped on one end, need to figure out plug configuration and where to place "+" and "-" nails for a clean un-spark filled test.
• Regarding the other site link in my last post, would you agree if solenoid is good, timer or Delay Module is the next test candidate.

 

[dieselcrawler]

Gasket may need replaced, depending on how damaged it might be upon removal. The solinoid I've had off of a similar motor at work has an oring, easily reusable. A little high temperature RTV silicone will reseal things if needed. Be sure to degrease the area well, spray can of brake clean works great, don't get much, if any, inside the injection pump.

I will check mine when I get home tonight, try to identify the wiring for you. You will need constant 12+ to the 'hold' coil, and just a quick touch of the 'start' coil to draw in the plunger.

 

[Industrial Toys]

It has been quite a few years. I believe the circuit board had it's own fuse on board. I remember being a little annoyed at this hidden item.

 

[dieselcrawler]

I'm sorry, but I didn't look at the wiring tonight. Was in dire need of brush hog therapy, and spend the time I had destroying overgrown fields...

 

[sriddle1]

dieselcrawler, No Problem, get to it when you can appreciate the help ! In the meantime I've switched to an outside project on my To Do List, capping outside window cornices with Azek Trim, great stuff. I had to make another trip to HDepot, apparently the 10mm long socket was too long, very tight in and around that solenoid but I found a 1/4" drive size and hopefully I'll tackle the outer bolt later today or tomorrow morning. Once I get that off and tested and it's OK then my sights will be on the Dimer/Delay Module, part number is M803344. I'll take a look to see if there's any fuse on the board mentioned by Industrial Toys. Also looking into the "Thermister", so far what I've read only address the 4400 Tractor.

 

[dieselcrawler]

Only had a minute tonight, but I did look at how the wires to the solinoid are routed, and took a picture for you. You will see the harness connection, it's the white plastic 3 blade circled upper left, and the circle middle right where you can see the wires going into the solinoid. Black is most likely ground, white is run/hold in, red is start/pull in... if memory serves me correctly. I DID NOT verify that tonight on my machine, I didn't have the time.



Does you have a volt/ohm meter and/or test light? If so, I can walk you through the process of testing at the white connector.

 

[sriddle1]

Do you have a volt/ohm meter and/or test light?

dieselcrawler, Thanks again for taking time to post the PICS, the information is greatly appreciated. YES, I checked my tools and many years ago I obtained a Sperry SP-5A 13 Range Analog Multimeter (still works), I copied the user manual down, long time since I used one....... With that, I believe you'd walk me thru obtaining readings of the voltage coming into the solenoid's wiring harness connection while trying to start the tractor. At least I'll know the "GAA-ZINS" are OK. NOTE in the 70s & 80s Navy Techs always talked about the electrical "GAA-ZINS" vs. "GAA-ZOUTS" flow when troubleshooting, not sure if they even use those terms anymore, I'm old

 

[dieselcrawler]

I checked the voltage at the white connector, tractor side. Did not get the results I had hoped, but know better what to tell you...

Wire color on the solinoid side of the connection is different than the tractor side. You will have to transpose as needed. Solinoid side, black wire is ground, and red is switched hot/run 12v +. I expected to find a 12v+ reading on the white wire when the key was in the start position, but NO DICE. Now I'm confused, but also not sure that my test is accurate, having the solinoid disconnected. I'll try to check it better, while connected. I'll let you know what I find.

 

[sriddle1]

Wire color on the solinoid side of the connection is different than the tractor side.

dieselcrawler, THANKS for your persistence. I found the attached Wiring Diagram applicable to my Production Year. I can see the White-Red-Black wires coming off the "Y2" Stop Fuel Solenoid PN: M806808. Looks like the White Wire connects to a White/Blue wire to the "Time Delay Control Module" PN: M803344 and "K2" Fuel Relay. The RED coming off the Solenoid connects to a Green/White to the "K2" Fuel Relay if I'm reading this correctly. Not sure how the voltage should read (using multimeter) at the Solenoid Connecto.r

Side Note: In the John Deere Parts Catalog it calls for a RING, PN: RG60092 to mate up with the Solenoid before installation to the engine, looks more like a metallic O-Ring than a surface gasket.

About the Multimeter, it's been a very-very long time since I ventured to use it, Note to self.....When taking measurements black probe on Black "ground" wire and Red Probe on power source or was that.......Black probe on tractor frame metal and Red Probe on power source. :muttering: