John Deere 850 Yanmar with air in fuel lines.

Post your questions or problems you are haviing with your Yanmar tractor here.

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Acleme1
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John Deere 850 Yanmar with air in fuel lines.

Postby Acleme1 » Sat Aug 05, 2017 8:30 am

Hi all. New to the forum, and out looking for some help. Recently I was brush hogging, and ran my JD 850 out of fuel. Rookie mistake. So I filled the tank with fuel, and bled the lines at the filter and the injection pump. I can get it to start, but then it dies and I have to bleed the lines of air all over again. I've done this a dozen times now and every time it's the same thing - bleed the lines, start the tractor, it guns for maybe 15-30 seconds and then dies again. When I bleed the lines , there's always air in the lines at both the filter and the pump.

And going from bad to worse, I spun and broke the bleeder screw at the injection pump. The engine is a Yanmar, and the injection pump bleeder screw can be seen here:
http://www.hoyetractor.com/bleed.htm

So I have a couple questions: Why do I keep getting air in my fuel lines? Also, can I just replace that small bleeder screw assembly without trying to dig out the broken bleeder screw? If so, what part number am I looking for?

Thanks so much for any help you guys can give. I'm at a loss for what to do here, and I really need to get back out and brush hog soon.

Thank you.
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Aaron
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Re: John Deere 850 Yanmar with air in fuel lines.

Postby Aaron » Sun Aug 06, 2017 1:17 pm

Do you get a good steady stream of fuel going into your injection pump? Be sure you can stream a quart or so of fuel without it slowing or stopping. My first guess would be fuel starvation but I'm not sure how you would be getting air in the system. I'm guessing there are no fuel leaks? You can also use a section of clear tubing between the fuel filter valve and injection pump to see where the air bubbles are coming from.

Norm
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Re: John Deere 850 Yanmar with air in fuel lines.

Postby Norm » Sun Aug 06, 2017 1:47 pm

http://www.hoyetractor.com/PROD/BB-3854.htm
I'm pretty sure this is what you need, or ask. They will sell you what you need.. Are you bleeding in proper sequence, first left on filter, then right, then pump screw? Bleed with full tank and full filter bowl.

Acleme1
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Re: John Deere 850 Yanmar with air in fuel lines.

Postby Acleme1 » Mon Aug 07, 2017 9:22 am

Thanks for the help, guys. Norm - that's exactly the part I need. Thank you so much. I couldn't find that part to save my life. I ended up using a bolt from the hardware store and a rubber washer, but I'll be ordering that part to make sure no air will be getting through.

I actually finally figured out the problem this weekend. It was in the fuel line. Either from the tank to the filter, or the filter to the injector. They looked okay, but air was definitely getting in there through one of them. Replaced them both, and brush hogged for 7 hours yesterday. It's such a relief to figure out a problem after trying so many different things.


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