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:

 

[Industrial Toys]

Sorry, I have not been following the thread closely. I don't remember. Is it possible to disengage the solenoid and operate the shut off manually? Like, old skool, ten dollar cable and knob. Maybe just as a test. Are you sure, you don't have a fuel delivery issue?

 

[dieselcrawler]

As I said in post #29, at the white plastic connector, find the terminals on the tractor that match up to the black (negative/ground) wire and the red (12v + with key Switch in 'run' position) wire on the solinoid side. I was not able to get a 12v + reading on the terminal that aligned with the white wire as I was expecting when I turned the key to the 'start' position.

Your volt meter needs to have a DC volts setting, and black lead should be ground (negative) and red, positive.

 

[sriddle1]

Industrial Toy, sorry but it's not possible to Shut Off Manually + Fuel Pump Working A-OK....

With dieselcrawler's help I believe it's either the Fuel Shut Off Solenoid or Delay/timer Module. I have coordinated with a TBN PM to move my reply in this Thread "Help Interpreting Wiring Diagram & Using Multimeter" to JD Owning and Operating for a large audience.

Before removing the Solenoid, I'd like to know with some certainty what are the acceptable readings coming off the Wiring Harness enroot to the Solenoid. Once I understand the readings I'll disconnect the Solenoid's Connector and take measurements on the Wiring Harness connector as the key is turned to START. Hopefully it will tell me if the upstream Timing Module & Relay output is bad or if the readings meet an acceptable range then the Fuel Stop Solenoid is more certain to be the issue. Once known, I will go-ahead and purchase the appropriate replacement.

THANK YOU BOTH FOR YOUR INPUT!

 

[Industrial Toys]

Not to confuse further, but sometimes if one does not understand how the circuit was designed, you don't know what to look for as far as readings. I have designed and built such circuits and used capacitor discharge to operate a fuel solenoid. You would get some strange readings if you didn't understand what was going on. Also, some outbound circuits have common collector outputs that require some electronic knowledge for troubleshooting.

So, no one can tell you what the coil resistance on the solenoid should be? That is both coils. So, if the solenoid moves freely, and is not burned up inside and swollen, then, two appropriate resistance readings should indicate a good unit.

 

[sriddle1]

Not to confuse further, but sometimes if one does not understand how the circuit was designed, you don't know what to look for as far as readings. So, no one can tell you what the coil resistance on the solenoid should be? That is both coils. So, if the solenoid moves freely, and is not burned up inside and swollen, then, two appropriate resistance readings should indicate a good unit.

Industrial Toys - Thanks for your feedback, what you said makes sense. From reading the various posts and blogs out there it appears (65% certainty) that either the K2 Fuel Solenoid @ $185.00 or the A1 Time Delay Control Module @ $213.00 are likely candidates for replacement. Transportation Costs to get my tractor (sitting in a garage with the FEL in the down position) to a repair shop before they touch it is $250.00 so I'm willing to buy a part.

As a layperson (before your response) I thought perhaps there would be some way to check via the Wiring Harness connector to see if the A1 Time Delay Control Module was sending the proper output to engage the Solenoid If that output was faulty then I could assume the A1 Time Delay Control Module was the issue without having to physically pull the Solenoid. On the other hand if that output was good then the Solenoid is probably the issue. I see now why dieselcrawler said: "I was not able to get a 12v + reading on the terminal that aligned with the white wire as I was expecting when I turned the key to the 'start' position.

Based on your response I see my overly simplistic view of taking readings is not a viable one. So in your opinion is my only option to pull the solenoid and do some sort of bench test (?) whatever that might be. In a previous reply dieselcrawler stated: "Simply removing the solinoid will let you test it, but be aware that if the tractor starts, you have no way to stop the motor until the solinoid is reinstalled, and it will likely leak oil from the opening." Unlike dieselcrawler I am not a knowledgeable mechanic so that didn't seem to be a viable approach based on my skill-mix.

 

[Egon]

With a starter lead pulled off the tractor would not start if testing solenoid.

 

[dieselcrawler]

With a starter lead pulled off the tractor would not start if testing solenoid.

Excellent idea... very simple, and very effective. Pull the trigger wire to the starter solinoid, remove the stop solinoid, and test by turning key to start position.

I'll look at mine tonight, as to how the starter is wired. You simply want to stop the starter from engaging, but not disconnect power to the rest of the system. Therefore you do not want to disconnect the big wire from the battery, as often the rest of the system gets its power feed from that point.

I'll post back with my findings on this new approach, likely later tonight.

 

[sriddle1]

Excellent idea... very simple, and very effective. Pull the trigger wire to the starter solinoid, remove the stop solinoid, and test by turning key to start position.

Egon, dieselcrawler, THANKS...I needed that.........Now we're talk'en, , just make sure you keep it simple, what to disconnect on the starter.........

Decided to go ahead and pull the solenoid in preparation for the test. A 10mm Box Ratchet Wrench does the trick for the rear bolt however the front bolt is in a VERY TIGHT space. Didn't want to use an open box wrench, can't get a good straight-on angle/leverage + afraid of stripping the bolt (been there done that). Looks like another trip to HDepot for a small body 1/4" Ratcheting Socket Wrench. Seems the 10MM short socket does the trick (access/fit) however my 3/8 Ratcheting Wrench + reduction socket to 1/4" drive + short socket is still too long for that confined space. Report back later......I'll get this off today.........I HOPE.....:drink:

 

[sriddle1]

Report back later......I'll get this off today.........I HOPE.....:drink:

SUCCESS :thumbsup: - The smaller 1/4 drive Ratchet Socket Wrench made it easy however that's really tight in there, wondering how I'll get it or the new part back in. :muttering: Selenoid still attached to Harness, I could push the plunger/rod up into the housing freely with some slight fluid gurgling sound. Pulled the PN information off the housing, Model: 1503ES-12S5SUC5S (WOODWARD / SYNCHRO START NO.) Part No. 119653-77950. Wondering if that's the original part, not that it really matters at this point. The engine compartment is pretty dusty, we're in a moderate drought here.....READY !

 

[Egon]

Gurgling sound?? I believe there have been some problems with the solenoid leaking??