j.d. 850 injection problem ?

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joel
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j.d. 850 injection problem ?

Postby joel » Fri Sep 25, 2020 7:41 pm

I have a john deere 850
when I bought it it had a slight miss and seemed to run very rich ,excessive black smoke , even at idle it has slight black smoke , I rebuilt the head resurfaced,valve job , new rings ,new head gasket , new injectors,
I still have excessive smoke and excessive diesel combustion noise[ clatter]
when I crack the injectors #1 slows the motor more than #2 or 3
does this sound like a pump problem or injection timing problem
thanks

winston
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Location: North East Texas

Re: j.d. 850 injection problem ?

Postby winston » Sat Sep 26, 2020 5:23 am

I'm sure your air intake is clean? Maybe timing? Has the injection pump ever been removed or shims changed?

Pistons and injection pumps are numberd 1, 2, 3 counted from the flywheel end of the engine.

Engine flywheel has 3 sets of timing marks. The sets are numbered to match the piston numbers.

Turn flywheel until the number 3 piston TDC mark aligns with timing index mark on starter housing. (Number 3 is the reference because 1 and 3 are hidden by the frame, etc.

Attach tool JDF-14 or an old cutoff piece of fuel injection line onto fuel injection line #1 with a drop catch can at the end.

Turn key switch on. Do NOT start engine. Push fuel shutoff solenoid plunger in.

Turn flywheel clockwise (viewed from flywheel end) until fuel flow stops.

Keep turning flywheel clockwise slowly until fuel flows again in a stream.

If fuel flow does not stop, you are on the exhaust stroke instead of the compression stroke.

Slowly turn flywheel counter clockwise until fuel flow changes from a stream to drops then stops.

turn key off. Flywheel is now at the point of beginning of fuel injection.

Check position of timing mark on flywheel. Timing mark on flywheel must be aligned with timing index on starter plate.

If marks are not aligned, for every 2.2 mm that the marks are misaligned, the injection timing is off 1.0 degree.

If timing is less that 1 degree off, no adjustment is necessary.

If more than 1 degree, adjust injection pump timing.

Keep in mind the flywheel turns counter clockwise.

If timing mark on flywheel has not reached timing index, retard injection timing by increasing total shim thickness under injection pump.

If timing mark has passed timing index mark, ADVANCE timing by decreasing total shim thickness.

Do NOT use old shims. Injection pump timing is affected by using old shims. Measure old shims to determine total thickness.

For every 0.1 mm of shim thickness there is approximately a 1 degree change in position of flywheel.

Shim sizes are 0.2 mm (.008") prodeces 2 deg (4.5 mm) on flywheel.

0.3 mm = 3 deg =6.5 mm.

0.5 mm = 5 deg or 11 mm.

Apparently there can be quite a bit of wear on these shims. They show a typical 2 mm shim that is now 1.1 mm.

joel
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Joined: Sat Nov 10, 2018 8:18 pm

Re: j.d. 850 injection problem ?

Postby joel » Sat Sep 26, 2020 7:00 pm

thanks for the info I pulled the pump out today found that #1injector pump delivery valve was installed backwards #2 and#3 were installed correctly # 1 must have been partially sealing and partially building pressure,causing a very rich mixture on#1 seems to run much smoother now no excessive smoke still clatters a little louder than my other 850 so ill still have to check timing but seems to run good

winston
Volunteer Poster
Posts: 5603
Joined: Mon Feb 01, 2010 7:29 am
Location: North East Texas

Re: j.d. 850 injection problem ?

Postby winston » Sun Sep 27, 2020 4:56 am

Glad you found the problem.


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