Oil & Fuel Fuel Pump Timing Help??

Mickey_Fx · Apr 21, 2006

Gotta give you credit for the effort you're going to Mark. This is out of my area of knowledge but I have a hard time beliving the small changes you've made to shim thickness has such a big impact on running characteristics.

If I understand where the shims are located, I suspect there is a helical gear set at the pump input and the shims are used to fine tune the built-in timing advance due to part/part tolerances. With helical gearset moving in/out will change the timing. I suspect you are correct that if you replace the pump, the shims/timing will have to be fine tuned to ths specific setup.

I suspect there is more to the problem than the shims and every time you remove the pump to change the shim, something else is affected.

Keep us informed and hope it doesn't take too mch more effort to find the cause of the problem.

mark777 · Apr 21, 2006

( I suspect there is more to the problem than the shims and every time you remove the pump to change the shim, something else is affected.)

Mickey, I suspect you're right. In a few short weeks I've repaired the hydraulic pump which DID have a problem....and repaired everything else that probably didn't, including a valve job.

I do have to make it run right, or well enough to find any other problems. I will include pictures of the pump rollers, pump and timing cover machined platform. And if you can make it out the cam lobes that the pump rollers contact.

The shims radically change the timing and I am surprised by how much. Just like static timing and old style distributor by advancing or retarding the complete unit.

mark777 · Apr 21, 2006

...and one of the pump and shims.

FL_Jerry · Apr 21, 2006

Man, I hope my pump never goes out.............Well if it does, I know who to take it to..lol

Jerry

Mickey_Fx · Apr 22, 2006

As I said before this is out of my area and from your pics, the shim is in a totally different area than I was thinking. Correct me if I'm wrong but looks like the shim is controlling the distance of the pumps to the cam.

Seeing where the shims are located, they do more than fine tune the timing, they affect the duration of the injection cycle.

Is there any way to change the timing without affecting the duration of the injection cycle? Without out going back and reading all your posts, I'm sure you've checked to insure the cam gear is indexed and meshing with the drive gear correctly.

Is there any centrifical advance on this pump or is it just static timing. If ther is an advance mechanism I'd take a close look at that for possible problems.

Hope some of the suggestions and your effort is helping with making progress.

mark777 · Apr 22, 2006

Mickey...yes the shims control the distance, contact pressure and cracking pressure timing between the pump rollers and cam lobes.

There are two distinct timing marks, one on the crankshaft gear and one on the cam gear...although the crank gear and cam gear drive the oil pump and hydraulic pump there are no marks or critical timing for the oil and hydraulic pumps.

No mechanical or centrifugal advance...the hand throttle is converted internally at the pump, to meter fuel volume using a rack and helical gears. The injection pump, when installed, appears to be working normally. The fuel delivery is free flowing and even at all the injectors. IMO as everything seems to be working mechanically, it is a question of the fuel entering the combustion chamber either too early or too late.

Just so you and everyone who has offered advice knows...I appreciate all the input. The tractor is just sitting in the middle of the shop and I walk up to it several times a day....and stare at it for long periods of time, and then walk away. I am grateful that it's my rig and not a customers.

mark777 · Apr 22, 2006

Jerry,

I think you can rest easy as I have heard repeatedly that Yanmar injection pumps just don't suddenly fail. They do however, wear out from fuel contaminents that create wear and sloppy tolerances on the plungers internally.

And WHEN I find out what I did...or what is wrong, I will shout it from the roof tops /forums/images/graemlins/grin.gif

Mark

Jagmandave · Apr 23, 2006

Man that must be frustrating, to work on one thing then have something seemingly totally unrelated act up!

I hope you find it, and I think it will ultimately go one of two ways. You'll either find it was something you did, or forgot to do associated with the hyd pump repair. Or it will be some complete fluke of a thing that just happened.
Here's the good news, you now know that your head, valves and injectors are in perfect shape!

normde2001 · Apr 24, 2006

I'm having a hard time believing this is a pump timing problem. How did it get off in the first place? Someone mentioned that a .004 shim = 1 degree of timing, as I recall you wouldn't even notice a couple of degrees advance or ****** in an old distributor/point ignition setup. I believe I would put the original shim(s) back in and look elsewhere, maybe get one of those $30 Harbor Freight compression testers and see if 1 of the adapters works, or rig something with an injector, and check the compression.

mark777 · Apr 24, 2006

Norm,

1) Hydraulic pump seal leaked, slightly diluting the crankcase oil and creating white smoke and excessive un-burnt fuel.
2) Hydraulic pump seal ruptured enough to dump excessive UTF into crankcase....1 1/2" above the dip stick level mark. Remove, replace seal and reinstall pump.
3) Change all fluids, filters and fuel, start and operate tractor. Severe loss of power, erratic RPM including engine stall. NO blow-by. Removed timing cover and inspect crank to cam timing marks at TDC...OK. Verified hydraulic pump gear has no relation to cam, crankshaft or hydraulic pump timing.
4) Remove, inspect and reset governor at 240° from point of contact (book specifications), reassemble and start engine. NO change in performance.
5) Remove, fuel, fuel valve assembly, clean and inspect fuel tank, flush with denatured alcohol, fuel pipes cleaned and blown out with compressed air, fuel valve assembly disassembled and replaced "0" ring, bleed screws, fuel filter and ALL urethane fuel lines. Pull and inspect all 3 injectors, replace, add fresh fuel, bleed fuel system and restart tractor...NO change in performance. Changed all 3 injectors from another (good running) 3T75U engine, removed exhaust pipe and muffler. NO change in performance.
6) Remove, inspect and fluid test cylinder head. Leaking intake and exhaust valves on #2 cylinder. Lite valve and seat grind and final hand lap. Valve guide bore is tight and within tolerances. Valve stem seals replaced, head reassembled and fluid tested with zero leaks on all valves. Pistons checked for radial play (slop), cylinder walls inspected for scratches, scarring and gap clearance (.002" feeler gauge will not fit in gap). Reassemble with new head gasket, valves adjusted and tractor started and NO change in performance.

At this point in time, and having done everything I could think of at least twice, I had to consider the injection pump timing. Originally (like you and many) I can not see how one problem is relevant to the other, and not a big believer in coincidence, but an approach of process of elimination. So... I removed the injector pump and discovered a mangled, distorted and broken shim that varied in thickness from .014" to .020" from side to side. Obviously (to me) someone has removed the pump before.

Certainly not an expert on these engines and fuel systems, but I have been inside many and even if there were a connection to low compression without blow-by...well that scenario seems highly unlikely. I just put this post up there so that you, or anyone else may see any flaw in my approach to diagnosing and fixing the problem...because if the shim kit does not fix the problem, then I am stumped.

Thanks, Mark

normde2001 · Apr 24, 2006

"I removed the injector pump and discovered a mangled, distorted and broken shim that varied in thickness from .014" to .020" from side to side."

So, according to my logic, somewhere in the middle of .014-.020 should work at least as good as before, with the original hard starting. I had 2 mottoes when I used to troubleshoot cash registers for a living. "The difficult we do immediately, the impossible takes a little longer", and "We strive for perfection, but settle for excellence"....Failure was not one of our options.

gary1611 · Apr 24, 2006

I am a highly experieced auto tech little diesel experience but i must side with norm all that to thin oil in the crankcase must have done some lower end damsge rings in particular and this is the only thing i have not read you checked the tractor ran fine before the leak with the shimmied shim i dont think the shim is the problem (cause and effect)
the shim will effect duration the amount of time injector sprays but its not going to do alot with timing sure you can move it a few degrees either way. but your going through all that and i think you'll find its something else (rings). i'd do as norm said.
its easy enough to rule that out. My .02c

legall- this post is for enterainment purposes do not try this at home. I do not guarantee that any of the information contained in this post is correct, workable, or factual. I am not responsible for, nor do I assume any liability for, damages resulting from the use of any information

gary1611 · Apr 24, 2006

Also the book for my yanmar shows the pump timing lobe as having a key way this would probly be unrelated to the hydro pump
bet one of those keys could be bent or wore wich would (posible dramticle) efect pump timing. i dont know how yours are.

legall- this post is for enterainment purposes do not try this at home. I do not guarantee that any of the information contained in this post is correct, workable, or factual. I am not responsible for, nor do I assume any liability for, damages resulting from the use of any information

DavesTractor · Apr 24, 2006

( Verified hydraulic pump gear has no relation to cam, crankshaft or hydraulic pump timing.)

Mark, I certainly respect your knowledge, but are you 110% sure the pump gear is irrelavent to the cam/crank/injection timing? I guess I need to pull the front off one of these engines or get out a manual to satisfy myself on this, but when you have checked everything twice you have to reconsider everything you "know". Keep us informed, thanks.

California · Apr 25, 2006

Mark,

Just thinking out loud. You have checked all the reasonable stuff so that leaves the 'impossible'.

Could there be a restriction downstream in the hydraulic system that causes a continual heavy load on the engine?

The other possibility with the past hard starting and mangled shims is that the previous owner knew he had a bad injector pump and put it back together anyway. It might be worth the trouble to take this pump to an injector shop for professional diagnosis.

Or since you have a similar engine on site swap pumps temporarily, and run each on the alternate tractor.

Good luck with this!

mark777 · Apr 25, 2006

Dave,
I am fairly certain that the hydraulic pump and any relation to timing does not apply. Although it is gear driven, all it does is spin consistent with the RPM of the engine, as does the oil pump. Even with the tractor running poorly, the pump, loader and 3PH operates perfectly.

I realize it sounds absurd that I removed, repaired and replaced that pump and the tractor developed the symptoms it currently has, AND that they are somehow not related...but I have spent days checking all the possibilities including removal of crank pulley, timing cover and verifying that the crank-to-cam gears timing marks are properly aligned @ TDC on #1 cylinder. My confidence was high on making the repairs, but I am now certain of one thing...I am not 100% sure of anything (LOL).

Mark

Jagmandave · Apr 28, 2006

This may not apply, but................

I overhauled a 911 engine that had mechanical FI (many years ago), when I did the disassembly, I simply removed the pump assy intact and put it right back on when re- assembling - thinking that this way it should be fine. When restarted, the engine ran like poop.

Wound up taking it to a Bosch FI guy who had to rebuild the pump and reset the shims to get it to run right - I still don't understand why it changed to this day.

Your idea of swapping out the FI pump might have some real merit - at least to eliminate that variable. I also don't think it's a timing issue...........

FL_Jerry · May 5, 2006

Any updates Mark?

mark777 · May 5, 2006

Hey Jerry,

Well...sort of. The number 1 barrel and plunger assembly in the pump is bad. Excessive wear on the guide, delivery valve and plunger. The 'book' says if one is bad replace all three. So my options are to replace the pump with used or rebuilt OR rebuild with new parts.

Rebuilding the pump is not that complicated and I think most any of us could do it, but I lack the bench test equipment to calibrate each plunger assembly to be consistent with the next. The pressures are dictated by shim thickness per each plunger...and all plungers have to equal and overall pressure........It looks like it would be a crap-shoot without the correct equipment to match, calibrate and test the assembled pump. I think I'll be going with the rebuilt...or a good used one if I can find one reasonably.

Not much of an update as it still isn't fixed, but thanks for asking.

Mark

Cord · May 5, 2006

I don't have any experience with the Yanmar pump, but I gave some knowledge about injection pumps and might be able to help you a bit.

Often the timing is taken off a plunger with a dial indicator. Yes, the setup is that tight. I don't know how the Yanmars are done. The timing can be set in a pretty good range. 15-18 degrees BTDC is common on my truck. I know some guys that run 21 degrees. Advancing the timing brings in more torque, better fuel economy but higher cylinder pressure and temps. A little is good, too much is bad. Retarded is safer but kills the power.