# 1986 john deere 850 fuel injector question



## carkivey3 (11 mo ago)

my tractor has been getting harder to start. i have had to hold throttle wide open to get it start then it runs fine. today it does not want to start. i have removed fuel lines from injectors to see if each is pumping fuel. all 3 are pumping but only shoots out about 1/2-1". does that sound right. i would think it would need more pressure behind it to create a mist out of injector. i guess i could remove an injector and see how it looks coming out of it. i am sure some of you have ran out of fuel and pulled these out till they shot out fuel. any help is appreciated


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## thepumpguysc (Jan 25, 2015)

U don’t pull an injector out to bleed the system.?? U simply loosen the fuel line AT THE PUMP INLET.. crank the engine until fuel squirts out of the line w no air and tighten it up..
THEN follow the steel lines that lead to the INJECTORS that are going into the head.. loosen the LINES UP AT THE INJECTORS and crank till u get fuel there w no air and tighten them up..
Do ALL THIS W THE THROTTLE AT MAX, wide open..
No try to start the machine..

if it won’t start,
Doesn’t this engine have a decompression lever.. where the engine spins real fast to heat the cylinders and then u close it for easier starting.!!
Doesn’t this engine have a glow plug in the intake to heat the cylinders..
Have u checked the compression.??


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## Fedup (Feb 25, 2014)

It has a thermostart, and yes, it needs to working in cold weather. Does it smoke at all while attempting to start? If not, then you may have a fuel related issue. If you're getting the usual amount of grey smoke while cranking, then the heater or the power circuit for it would be suspect.


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## carkivey3 (11 mo ago)

i know how to bleed system. if i pull injector it will be to look at spray pattern.
no decompression lever.
no glowplugs. electric heater in intake manifold. yes it works and does make it sound like it helps but still wont run
no compression check yet


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## carkivey3 (11 mo ago)

little to no grey smoke. thats why i want to know about injector pump pressure


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## bmaverick (Feb 20, 2014)

carkivey3 said:


> little to no grey smoke. thats why i want to know about injector pump pressure


Is the fuel filter new? Is the fuel bowl recently replace with the o-ring? 

And when was the 40+ year old fuel tank drained cleaned and put back into service? 

Your JD850 in green paint is really a Yanmar YM2500. 

Do you have TM1192?

I've owned a JD850 and then went full Yanmar with the same engine with PowerShift vs. the gear. Got 'live' PTO doing the swap.


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## carkivey3 (11 mo ago)

i have the 3t80j engine. i removed fuel line to injector pump and had full flow out of tank thru filter. i might be changing my mind about fuel pump being weak. i pulled fuel lines off injectors again and moved them to a less restricted area and they spit out fuel 10". tried to remove injector without proper tool but none budged. now i want to remove them and do compression test. i will also remove valve cover and see if any valves look suspicious. 2600 hrs on engine


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## thepumpguysc (Jan 25, 2015)

Those injectors can b a real bear to remove.. Hoye tractor rents the tool, but for anyone who owns a Yanmar should own an injector puller..
I think it comes to 50-75.00 if purchased..
I ended up buying 1.. it’s a really well made tool..
1 trick to trying to get it to turn is..
Leave the line in the injector if your going to use an adjustable wrench..
Otherwise you will collapse the inlet on the injector and u won’t be able to get the line back in it..
Of course, once u get it to turn a little, remove the line..


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## thepumpguysc (Jan 25, 2015)

1 more thing I tried to get the injectors out is..
I screwed in a bolt & washers where the fuel return line goes.. and used a different slide hammer to TRY to pop them up.. no go..
Again u have to be careful, there isn’t much thread in the top of the injectors, so the bolt CAN strip the thread out.
U can also loosen the nuts holding down the injectors and spin the engine over to use the engine compression to pop them up..
Good luck.


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## bmaverick (Feb 20, 2014)

carkivey3 said:


> i have the 3t80j engine. i removed fuel line to injector pump and had full flow out of tank thru filter. i might be changing my mind about fuel pump being weak. i pulled fuel lines off injectors again and moved them to a less restricted area and they spit out fuel 10". tried to remove injector without proper tool but none budged. now i want to remove them and do compression test. i will also remove valve cover and see if any valves look suspicious. 2600 hrs on engine


You really need to get the TM1192 service manual before something breaks. 

The link in my signature is to the Yanmar Tractor Owners Group. membership is free like this forum. Then go the the WIKI > RESOURCE PAGE > MANUALS. download the TM1192 and the other ones for your machine.


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## carkivey3 (11 mo ago)

i have a service manual.it shows removing the injectors the same way thepumpguy just described.. i tried using compression to remove. number 1 moved enough to create a little blowby but 2&3 never moved, could be sign of low compression. i looked at valves and they all appeared good. pulled tractor and it fired and sounded smooth at wide open throttle. as soon as pushing it clutch motor dies down and shuts off. next i am draining all fuel and refilling even though i had just ran it for an hour on current fuel


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## carkivey3 (11 mo ago)

drained and replaced fuel, no change. injectors are a bear to remove. i was able to remove 2 of them. while soaking and waiting on 3rd, i connected the other 2 injectors up pointing away from me of course. turned over engine and saw no fuel mist. dropped a rag in front of both and they never opened. disconnected both to make sure it was pumping fuel. it was but apparently without enough pressure to open (needs 2275 psi to open). sounds like bad pump. does anybody agree


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## thepumpguysc (Jan 25, 2015)

U would be correct.. u saw it with your own eyes..
The pump isn’t pumping enough fuel to open the injectors.. which = bad/worn out plunger and barrels..


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## carkivey3 (11 mo ago)

thepumpguysc said:


> U would be correct.. u saw it with your own eyes..
> The pump isn’t pumping enough fuel to open the injectors.. which = bad/worn out plunger and barrels..


how long will it take to rebuild


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## thepumpguysc (Jan 25, 2015)

Depends on the availability of the p&b’s.
I’ll know when I get the pump..
I have all the gaskets needed..
If the p&b’s are available, just a couple of days..
U can reach me directly at::
[email protected]


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## bmaverick (Feb 20, 2014)

carkivey3 said:


> how long will it take to rebuild


You are in good hands. He's the best for rebuilding the John Deere and Yanmar systems. In fact, he knows so much more and does plenty of the Japan tractor brands too.


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