4200 compact, injector replacement or rebuild, compression test and injector removal

[actionpaintball]

I have been troubleshooting a power loss and hard start condition on this tractor I recently picked up. I went through cleaning the fuel system, filter and replacing the thermistor and fuel shutoff solenoid. The filter assembly and lift pump are good (lift pump replaced).

1999 4200 Yanmar 3 cylinder #TNE78A-1142. Symptoms: Very hard to start, will start, run and idle immediately with a small puff of starting fluid (1/4 second blast). Had bad fuel (water mix), drained and re-drained, cleaned. Will run and operate as long as the throttle level is 1/4 or above, will usually die at low idle if the handle is pulled all the way down. Probably only has 1/3 to 1/2 the power it should; everything operates fine until a load is put on the hydraulics. Air filter checked, manifold heater working fine. A little white smoke on start up but cleans up with no noticeable smoke after a couple minutes. The injection pump seems to be putting out good pressure (just a quick visual from loosed nuts). There does not seem like any air is in the fuel system. Now, time to pull the injectors. I made a quick puller out of iron pipe with a slot ground out for the return nippples; welded a stud (cut off bolt) onto a 12mm 1.5 lug nut (the injector thread size is 12mmx1.5). A washer and nut turned about 10 times yanked the injectors out enough they could be removed after soaking in some PB blaster overnight. The best thing is this can be done with the fuel tank in place.

I then connected each injector to an output on the IP and could not get any spray pattern on any injector nozzle. I will go and try cranking longer tonight...but my initial guess is the injectors and/or the IP is bad. While the injectors are out I want to do a dry and wet compression check. I have various diesel compression test adapters but they are all made to replace glow plugs or threaded connections. I can make an adapter on a lathe easily, but how would it seal? I looked at some of the commercial adapters and they don't look like they seal either. How does the factory injector actually seat and seal?

My big question is: Where do I get the injectors from? I called a few places and they wanted the "roll numbers" which are not visible at all. The JD part number AM878593 are over $200 each. Anyone have a source for rebuilt or new injectors? Part number? Should I just get mine rebuilt for about 70 to 100 bucks? Anyone make or buy a good compression adapter, and what size/diameter did you use?

Thanks, and I will attach a few pics of the puller in action, and old injectors. It seems like they are in rough shape even for 18 years old.

 

[actionpaintball]

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[thepumpguysc]

There is a copper gasket on the bottom of the injector that seals the compression..
You can but a Master DIESEL compression tester from Harbor Freight or ebay for around 100.00 & resell it when done.
It sounds to me that the rack on the injection pump is sticking & has too much drag on the plungers, hence the shutting off at low idle.
The governor cant overcome the sticking/dragging rack inorder to keep it running.
Did you have the throttle "wide open" when checking the spray pattern on the injectors??
IF NOT, the rack was to stuck to allow fuel to get to the injectors and that's why it didn't spray fuel..
Its THE PUMP.. Pull it and move the rack back & forth..I can redo it for you if you want to contact me, just put an @ a o l dot com after my name.. There a "sticky" that show YOU how to do it tho.. Good Luck.

 

[actionpaintball]

The rack moves very freely. I did crank up the throttle and got a double V spray pattern on one test injector. I am not sure if that master compression test kit would work? Do those pencil bodies seal and clamp down like the oem nozzle? I was thinking of taking the needle out of one and soldering the return holes shut for a compression blank.

 

[JimRB]

You did change both the fuel filter and the water separator filter?

 

[thepumpguysc]

You say you have a "test inj.".. You have to braze/plug the return, take the needle out of the nozzle AND cut the tip back to the large opening, past the small spray holes.. otherwise the compression cant get past the small spray orific's..
Do you have ANY #'s off the injector body or nozzle itself??

 

[actionpaintball]

Good points on the injector test body....havent got that far yet. Replaced the filter element, not sure on the other filter, don't see one. It was a pain but got the "roll" numbers off the nozzle: oCu2, 50P22 4TE0. Between 3 injectors, pretty confident they are the digits.

 

[thepumpguysc]

In order to get the #'s for the nozzle tip, the inj. has to be disassembled.. the bottom nut has to be removed.
On your test injector, is it an "extra"?? Did it come out of THAT engine?
What I'm getting at is, you could practice disassembly on THAT injector and not mess up the "good ones"..
I'm pretty sure on that type of inj., you'll need a special rig that puts pressure on the tip & holds it tight into the body, so you can remove the bottom nut and not break the alignment pins inside..
IF you try to hold the body in a vise and then break the bottom nut loose, you also break the alignment pins and that's "no bueno"..
BUT, if you do that on your extra injector, who cares aslong as it comes apart & you get the correct #'s and then you can remove the guts & grind the end off the tip to make your compression tester..

 

[JimRB]

Good points on the injector test body....havent got that far yet. Replaced the filter element, not sure on the other filter, don't see one. It was a pain but got the "roll" numbers off the nozzle: oCu2, 50P22 4TE0. Between 3 injectors, pretty confident they are the digits.

I have had both the filter and the water separator get clogged. The Deere parts manual may give you a clue about where the filters are. If you already changed both then never mind. But you need to make sure both the filter and separator are good before you get inside of expensve parts. John Deere - Parts Catalog

 

[JimRB]

On my JD 870 which is a Yanmar tractor, the water separator is under the tank and the fuel filter is up by the pump. Of course your tractor may be different as it is years newer than mine, like maybe 2 years newer and it seems a replacement for the 770 according to Tractor Data.