Yanmar injection pump question

[JoeJChin]

I am looking for some help with trying to determine if i have a problem with the Yanmar injection pump on my JD 750 tractor.

I was running the tractor and had shut it off to refuel it, it was only off for about 20-30 minutes

Haven't been able to get it started since,,,,,,,,,,,,...

I went thru the whole bleed the system thing several times , just to cover that problem , but the tractor was not run out of fuel , just shut off.

There is no electrical shut off on this tractor just mechanical.

When i took the inspection/access plate off of the side of the gearcase the pump is mounted to, it looks as though the rack on the pump is not moving at all
when moving the throttle lever from shut off to full throttle position .

I pulled the pump according to the instructions in the tech manual i have .

The rack on the pump that moves with the throttle lever is very difficult to move back and forth .

Problem is , i don't know if this is normal or not .

WAs hoping someone on here might have had one of these pumps out and knows if it should move very freely or it takes some effort ( i kind of need to put both thumbs on it to press it )

This is a link (if it works ) to a picture of the pump on my tractor .

http://www.jhdiesel.com/Mvc-017s.jpg

The picture on the right shows the rack that moves with the throttle linkage (a fork sits over the pin sticking out of rack and slides it open or close it .


thanks

Joe

 

[winston1]

The only mention of rack moving in my ym220/226 manul (very similiar to your 750) says it should move smoothly. Interpret that as you will. Although I have no on hands experiance with these pumps I would bet a dollar to a donut the rack should move easily. If your rack would not move from full throttle to shutoff that would be another good indication it is to hard to move. Have you sprayed it good with a lubricant and tried freeing it up?

 

[JoeJChin]

I haven't sprayed it with anyting , yet .

It kind of runs in an oil bath,or spray , since it is just off the cam shaft the runs the pump .

I'm not sure if something couldn't have gotten into the "fuel side" of the pump and gummed it up , althought ,it was running fine 30 minutes prior to my problems

Joe

 

[dirtdonkey]

Just went through a similay problem with my YM 3110D tractor. Shut it off and would not start. I installed a new injector pump, just like the one you have pictured and from what I discovered I can't believe that your problem is with the injector pump. Sometimes it appears to be hard to move, due to the linkage that attaches the throttle to the governor, if its anything like the Yanmar setup on the injector pump. If you think its stuck injecting a small amount of WD40 into the sliding mechanism wouldn't hurt to make sure its freed up. The small amount of WD 40 to the total quantity of diesel oil in your system would be insignificant but it might free up whatever you think has it stuck. I would look for some other reason for not starting, the injector pumps hardly ever go bad. How many hours are on your tractor?

 

[JoeJChin]

dirtdonkey

I talked to a couple injection pump shops , both told me that the rack should slide very easily , i need to use two hands to hold the pump and push very hard with both thumbs to get it to move at all.

I also found that the no 1 and no 3 plunger?? can be pressed in without too much effort , but the no 2 plunger doesn't want to move at all.

I am going to try spraying it up with someting , to see if it loosens up at all , before buying another one .

This is an old tractor , and there are 3200+ hrs on the clock , which doesn't work, so no telling how many hours are actually on it .

I am guessing it has had an engine rebuild at some point, (block is a different color ) and pump was probably replaced , rebuilt , at some point.

Guy i bought it from buys and sells old equipment , so no record on what was ever done to this tractor .

I'm not a stranger to heavy equipment ,or full size tractors, (spend a lot of time baling hay on a dairy farm) but never had any of the small tractors.

When i tried it out before buying , it seemed to run well enought for what i needed it for , it was a little rough , but i won't put very many hours on it in
the course of a year .

Only bought it for pushing a little snow now and then .

I only bought it a month ago, and only ran it for about 2 hours, (thats the part that sucks the most, so far it will cost me $300 / hr........... to run it )

What was wrong with the injection pump on your tractor ?

Joe

 

[dirtdonkey]

With that many hours you may need a new pump. I thought it was my pump becuase I was only running on 2 cylinders instead of 3. When I disconnected the injector lines from the injectors and then cranked the tractor, while flooring it, I found I was getting some fuel out of #2 and barely any out of 1&3 so I assumed the pump was bad. Come to find out I had dropped an exhaust valve seat in #1 cylinder so the injector pump was probably still working but not as good as the new one I put in. Wasn't real hard installing the new pump. Good luck with getting everything back up and running.

 

[JoeJChin]

dirtdonkey
Well , i decided to take a chance and try to loosen up the rack on my pump .
Figured i did'nt have anyting to loose, i was going to buy a new pump , might as well try it .

Took it into work with my and started soaking it with kroil and working the rack back and forth. When i started, i needed the help from a screwdriver handle to push the rack , after about 10 minutes of squirting with kroil and working it it started to loosen up , and now moves freely .
I also took out the center delivery valve holder , that was piston that wasn't moving .

I didn't really find anything inside , but after flushing it out and reassembling , i was able to move the piston .

Going to try to find time to re-install the pump over the weekend and see if it works ........

I still don't know how a pump could go from running , to siezed up , in the 20 minutes the tractor was shut off to refuel...........

Also going to try to install a better fuel/water seperator / filter assembly .
One of the injection shops i talked to wasn't very fond of the stock filter assembly on the tractor and thinks that might be what causes some of the injector / pump problems he sees.

Will let you know how it works out .

Either i saved myself $600 ,or i wasted a couple hours of my time......................


Joe

 

[Neat 1500]

Either i saved myself $600 ,or i wasted a couple hours of my time......................Joe

you tried, no one can have a go at you for that! :thumbsup: thats more than most people attempt.

 

[Gunny]

I've wasted a lot more than two hours on something less expensive that that plenty of times. Guess I'm like you and several others here, I'd rather tinker around with something and see if I can fix it rather than just throwing my hands up in the air and go buy new. If something can be fixed, I want to fix it, I've always got more time than money!

 

[dirtdonkey]

I try to fix everything prior to buying new, just like others mentioned you have nothing to lose. I also find that I learn a lot by taking things apart and then trying to get them to work. Have you bled your system before? I'd make sure you have a good filter system coming out of your tank that is also a water separator before starting. That way you know you're getting clean fuel with no water and the rest is just following the priming instructions and firing it up. Good luck and I hope your hard work pays off for you.

 

[JoeJChin]

Well been playing with the tractor all day today , (closing in on 8:00pm now) and no luck .

First thing i did was drain out all the old fuel,, flush out the tank , so i could start clean(don't know what might have been in there when i bought the tractor)
I put a compleley new fuel filter assemble on it , the old one looked like it might have been leaking at the shutoff valve and fittings, I also changed all the fuel hoses .
I wanted to eliminate any place it might be leaking or sucking in air when trying to bleed it .

While trying to bleed it , by cranking the engine over , i finally got a little bit of fuel comming out of the line at the #2 and #3 injectors, nothing at the # 1 injector.

How much fuel should i be seeing at the injectors , while cranking the engine?

What i am seeing at no 2 &3 looks like just a few drops at a time , and i have lines quite loose

The amount of fuel comming out kind of looks like it would if you had an "eyedropper " and were squeezing a drop or two at a time out of it .

I really don't want to buy an injection pump if i don't need it , but i'm not sure were to go at this point......

If i should be seeing more that just a few drops while cranking , then maybe the pump is bad .

any help appreciated
I have one more day of "OK" weather , then we drop down into teens for a HIGH temperature for the next week.......................

thanks

Joe

 

[winston1]

If you started with the closest bleed to the tank and worked your way to the injectors and are only getting an eye dropper on two of them and nothing on the other one it is possible your pump rack is not wide open or your plungers are sticking. Try tapping on the pump a little, probably won't help but won't hurt either. Again, my answer is based on you having a good/bled fuel supply.

 

[dirtdonkey]

I was amazed when I saw all the more that comes out when the pump is working. Its a very small amount at an extremely high pressure, 2100 PSI, according to the manual. The new pump I installed put our far more than my old pump but my tractor seemed to be running fine with the old pump when it quit one day. Remember all it does is come out as a fine mist from the injector into the cylinder when it works so you're not looking for a large volume. I'm assuming you're checking it with the throttle held wide open while you're cranking the tractor over? I was where you are when I ordered my new pump, because I thought my pump was the problem and everyone I spoke with seemed to think the same thing. Its a lot of money for the pump though so I'd check to make sure there is nothing else wrong before I ordered a new pump. Like Winston said you have to make sure that you bled the pump good or you won't get anywhere because it can't pump air.

 

[JoeJChin]

Well .

Time to post an update on this problem ...........

Ended up buying a new injection pump. It was the only thing left to try that made any sense.

Turns out that was the problem , while bleeding out the new pump , I (like dirtdonkey ) noticed a noticeable increase in the amount of fuel coming out at the injectors .

Tractor seems to start easier now also .

Now all i have to do it check to see if the timing is ok on it.

I installed the new pump with the old shims on it , i didn't run the tractor much at all, just to see if it would start and run .

Have to check out the timeing procedure for it .

Thanks to everyone for their help

Joe