# John Deere F935 question...



## LlanoDeere

I have a John Deere F935 72" front mower with a Yanmar 3 cylinder diesel engine.
There are three wires that go to the fuel shut-off solenoid (1 white, 1 black, and a smaller pink wire).
When I turn the key ON the white and pink wire get 12-volts. After a few seconds a relay in the control module "clicks" and the white wire looses 12-volts. Is this normal? Does anyone have a F935 or F925 that can tell me if this is normal?


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## MFreund

What problem are you having?? I am assuming cranks but no start?? I do not have one but you need to post more info. What caused you to find this out. Now more importantly, what is the story about the avatar you have and can we see more pictures and the story behind the dozer!!!!!!!


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## MFreund

What problem are you having?? I am assuming cranks but no start?? I do not have one but you need to post more info. What caused you to find this out. Now more importantly, what is the story about the avatar you have and can we see more pictures and the story behind the dozer!!!!!!!


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## MFreund

I looked up the fuel supply circuit operation for a deere 4310 (has a yanmar diesel) and it said there should be two wires with 12v.The second helps the fuel shutoff soleniod overcome spring pressure. After the pressure is overcome it requires less volts to hold it open My wires are black orange and white. I do not have access to tech manual for f935 its on a different cd Hope this helps. My unprofessional opinion is Yes this is normal.


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## LlanoDeere

I bought this used F935 about six months ago from a guy at a swap meet. He acquired it from an estate auction and did not have any history on it.

I did not want to list all the problems thinking it might confuse readers and possible influence the answer/s.
The basic thing I need to know is if the fuel shut-off solenoid is working correctly. 
“There are three wires that go to the fuel shut-off solenoid (1 white, 1 black, and a smaller pink wire).
When I turn the key ON (not starting just ON) the white and pink wire get 12-volts. After a few seconds a relay in the control module "clicks" and the white wire looses 12-volts. Is this normal?”

I have had different problems with it and am wondering if they are related. Originally it would start but took some time to reach full throttle. I thought this was normal and meant the motor was not warmed up yet.

Problems I experience:
q	I mow fine for a while and then the PTO shuts off. I then move the PTO switch off and on and the PTO engages normal for a while then shuts off again.
q	Mowing normal and the engines tries to die…. To keep the engine from dying I return the foot pedals to neutral and the engine idles…. If I give it forward or reverse it dies.

I am also wondering if these problems are related to the interlock (safety system…seat switch, brake switch, etc.).










As for my aviator…. I found out the hard way NOT to use my 25,000-pound CAT951C after weeks of rain. I left it in the ground for a few months and had my country neighbor help dig it out with his New Holland skid steer.


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## LlanoDeere

Photo story behind my of my avatar...

http://www.moorewebsite.com/cat951c.htm


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## MFreund

*Where I would start*

I feel when diagnosing sight unseen the more info the better. As for the dying while mowing and slow engine speed I would change the air filter and the fuel filter. It seems to me the engine cannot breathe. With load it is struggling. Possibly there is a scum in the fuel tank from sitting, diesel will have bacteria grow in it after sitting and will plug the fuel outlet at the tank and the fuel filter. Also check the fuel cap vent, when it slowes down open the cap and see if it has vacuum on the tank. If it was mine I would drain and flush the tank with diesel, I know it will be very hard to waste $4.50 plus diesel. As for the mower shutting off I would check the seat switch for adjustment and corrosion. Try these and keep posting updates. The pictures are AWESOME. Big equipment is great until it is stuck!!


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## LlanoDeere

Thanks for everyones help! 
My solenoid is bad. The white wire is the "pull coil" for the initial pull to overcome pressure. The pink wire is the "hold coil" to keep the solenoid open. My pink wire does not hold the solenoid open even though it has 12-volts. I'll replace the solenoid and see how everything else does.
The solenoid may be related to the PTO problem since the control module monitors the fuel shut-off solenoid and may shut off the PTO when it sees the solenoid off.


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## MFreund

*Keep posted*

If that fixes all the problems let us know


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## LlanoDeere

The new solenoid fixed the problem. Thanks to all!


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## markeie

no problem running obvious leave it alone presure shut off switch.,... but do u know how 2 git the ford. petal to press easy and the brake not so sensitive like ya superman if u mess up lol have good 1 if you git diz chit lol !!!!!!!!!!!


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## markeie

And by the way why r u bn that noisee into elec and gas prob? No start go 2 compression? Cylinder wash dump and change oil fuel gets into oil on hard cold starts and she aint so young no moe either huh how many hrs there friend are ya killing grandma one more year you old bagger lol


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## jaguarguy

I have a F935 had the same problem. Before you buy a solonoid there are 2 relays that work that solonoid. One activates the fuel solnoid when you turn the switch on and holds it for 12 seconds on 12 volts then it shuts off and the low voltage relays take over and hold the plunger in to keep the fuel on. The relays are behind the seat on the left side. I looked at the John Deere shop manual at the dealer and it did not show one of these relays. I own some older Jaguars and I thought their electrical system was a real pain in the rear, but I believe John Deere has them beat.
Hope this helps, 
jaguarguy


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## jaguarguy

LlanoDeere said:


> I have a John Deere F935 72" front mower with a Yanmar 3 cylinder diesel engine.
> There are three wires that go to the fuel shut-off solenoid (1 white, 1 black, and a smaller pink wire).
> When I turn the key ON the white and pink wire get 12-volts. After a few seconds a relay in the control module "clicks" and the white wire looses 12-volts. Is this normal? Does anyone have a F935 or F925 that can tell me if this is normal?


I have a F935, I bought used and it would start and go dead. It about ran me nuts. The fuel cut off solenoid is a electric magnet when you engage the starter a 12 volt relay pulls the magnet to open for a couple of seconds and then stut off and a low voltage relay holds the magnet. That low voltage relay was bad on mine. Yes that is normal the relay are right behind the seat. Hope this helps.

Ed


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