790 Sporadic Starting

[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??