I finally seem to have the hydraulics working. The engine wasalso purring like only a 6 cylinder can after a rebuilt injector pump was installed. But after 20 gallons I've developed a popping through the exhaust. It starts out very minimal, but as the engine gets hot, the miss gets more pronounced and it wont go away with revs. Eventually it seems to get a double miss and then it wont work at all and I need to limp it back the shop. Surprise, when I started it the next morning and it was cool, it ran purrrfectly... for 15 minutes until it was hot. There is no smokle to speak of, either cold or hot, just the black when I stab the throttle. Double checked the valve lash, the filters, the fuel hoses, the return hoses and t's, the check valve in the injector, replaced the lift pump, checked the return flow output. The only odd thing is when the return hose is disconnected at the pump the miss gets MUCH WORSE. When I reconnect, it runs smoother. Sent the injector pump back the the re builder who thoroughly checked it out and found nothing amiss. Tried replacing a pair of injectors in in sequence 1-5, 3-6, 2-4. No help. Beyond frustrated, the 15 minutes is such a tease as how well it can work, but this is a nightmare again. Anyone got any helpful ideas?
Take the pickup out of the tank and clean the screen. OR, put a tee into the supply to the injection pump and run a line to the cab with a vacuum/pressure gauge to see what the fuel supply pressure is doing when it loses power. And then clean out the fuel system, possibly pressure washing, or removing and cleaning the tank. What was the hydraulic solution? You mentioned a new pump in the other thread, is that the new injection pump you mention here? or a new hydraulic pump?
Follow the return line.. if it goes back into the filter head or fuel INLET somewhere.. it will run worse, as your introducing air into the system when you break it loose. Its a "rotary pump" right?? Stanadyne.. Theres 1 pumping unit supplying ALL the cylinders.. so blaming the pump for a "skip" on 1 cylinder cancels out the inj. pump. UNLESS it has a fuel SUPPLY problem.. THEN your chasing air.. Have you taken your air hose & blown back thru the RETURN LINE, back to the fuel tank?? DO IT..
Did both of those already, but I will run a gauge to see the pressure
I replaced the entire return line with a new one I can easily blow through any of the inlet or return lines with just my breath.
Thanks for the intel on the pump. I did not realize that. I'm going to mount a temporary gravity fed tank directly to the injection pump this morning to remove any possibility of air getting into the system. Ive already replaced the hoses and orings but there still might be something. I dont see any bubbles in the return line when I put a clear one on just to check this out. Just a steady fuel slow coming out of the line. The miss is very exact, as though it is on just one cylinder every revolution. It is not random, like the occasional air bubble.
Is it possible that an injector could be bad, or even two and even though I replaced the pairs it was still leaving at least one somewhere that is erratic?
It is a new injection pump. The rough running engine was part of the hydraulic problem. This tractor seems particularity sensitive to any intermittent power pulses to the hydraulic system. There is a LOT of hydraulic demand and not a lot of reserve available form this relatively small engine. So what seems like a lack of hydraulic power can also be low engine power to the Hyd pump, ( assuming everything else is working right) even though the RPMs are there. Even when I only have a slight stutter with this new problem, the hydros go to **** like before. When I have the engine purring, the hydros are all there. BTW, as someone posted in my hyd thread, don't even try to diagnose a hyd problem until you have a flow meter. It is the key tool of any repair.
Usually when you send an injection pump in you send the injector nozzles with it to be checked. Bob
This is an excellent suggestion that no one made to me prior to sending in the inj pump. So you are saying it is possible?
It is possible to have a bad injector. And a bad injector is the most likely cause of skipping (after fuel starvation). When you replaced the injectors "in pairs", did you put two new ones in 1 and 5 and then switch those two new ones to another two cylinders? Or all new injectors?
I originally switched them as pairs, but have since (today) just replaced all of the injectors. The problem continues, although now it seems like a more consistent roughness. When I try to force it to run, such as move in 2nd it emits grey smoke and has no power. What could be changing with temperature? It is definitely temperature related. Does timing change with temp? It will start right up again when I shut it off, and if I let it cool, it runs as smooth and powerful as I could wish.
Post the PUMP # please.. The timing changes w/ rpm, like a distributor.. Its VERY COMMON to miss the hole in the gear w/ the key on the drive shaft.. 1/2 in & 1/2 sheared. Did you check your FEED/INLET pressure at the injection pump inlet?? Have you moved the pump any?? rotated it in the mounting slots..
I'll get the pump number a.m I'm 90% sure I got the key right. I didn't need to force it. But even if it were half a key of, why would it run smoothly and then at temperature run rough? I haven't checked the pressure, other than put my finger over the end while cranking and it has a strong pulse and steady squirt. The lift pump is brand new JD unit. I have left the two alignment marks lined up. It ran really well with them there for 20-40 gallons after the pump was rebuilt and then last week this issue popped up. Same fuel, same jobsite. Really nothing changed, just have this rough engine once warm.
SO another day of trying to figure this problem out. Went through every fuel line, every end, every o-ring and checked for suction or pressure leaks. Built two inline clear hoses that I could splice into the sections and check for bubbles. Everything checked out perfect, there were no issues. Yet the roughness still came on for no apparent reason. There were no bubbles in the hoses and no restrictions. Just to be sure, when the roughness occurred, I removed the hose at the pump and immediately replaced it with another hose that ran directly to an aux tank of diesel. It didn't help, but I wanted to be sure. I also checked the check valve, the little glass bit on the return. It is clear and free. So it is NOT any fuel line or delivery problem!
I did note one interesting thing, perhaps it will shed some light to you guys. The measured temps, from 1 to 6 on the exhaust manifold, are 190, 210, 230, 235, 210, 195. BUT, when the roughness occurs, the temps are 190, 210, 310, 315 , 210 and 195! The center 3 and 4 exhaust goes up 80+ degrees!!! I did this several times and each time it registered 65-80 degrees hotter as soon as the missing started. Once time passed, usually while I was changing a line or something and I restarted, it was smooth until at some point, from 15 to 60 minutes later and always at a low RPM setting, the missing and roughness starts again. I have no clue... Hope you do.
Head gasket/cracked head or block?? leaking between the 2 cylinders.. Starts when the engine gets warm, crack opens up.. & seals when its cold..?? Try taking the thermostat out & see what it does.. Sticking valves??
I don't think it is a temperature thing, although it doesn't do it cold. It can "reset" after I shut it off after a brief pause while it is still hot. I ran yesterday for 1.5 hours, it was perfect. With many periods of on and off RPM power as I climbed out to move material at an idle. Then one time when I was letting it idle after working it started again. The coolant is clean, the engine is not overheating. I suppose it could be a sticking valve and firing into the exhaust manifold. But two of them every time? And why would it start this all at once after so many gallons of perfection after the pump rebuild? There is no blowby and it only makes grey smoke when I try to rev it to clear it. Reving doesn't work. thepumpguysc, Is there any scenario where the injector pump might cause this? It still seems like a pump with something loose or floating around. I'm thinking excess unburned fuel is going into the manifold and igniting from heat.
Not to my knowledge.. Inside the pump is a "cam ring".. just like a camshaft except in a circle.. the lobes hit on the same cylinder every time.. sometimes the lobes get flattened/smashed but that would give low to zero fuel delivery.. The fuel coming INTO the pump, goes OUT OF the pump & is recirculated w/ every stroke of the lift pump.. "IF" there was something floating inside the pump, it would plug off the return connector & shut the engine down.. I have a test for ya..{somehow} REMOVE the checkball fitting.. completely from the system.. hook your return lines back up & run the machine & see if it continues to act up.. BTW> you still haven't posted the pump #'s OR ran a pressure gauge in the system.. Just remove the return connector & get back to us..
The pump is a DB4629-5304 RE67597. I unhooked the return at the elbow and it made no difference. I then took off the glass ball return fitting, (sprayed fuel everywhere) and it made no difference. I then blocked the output with my finger for 10-15 seconds. It is quite difficult to push down hard enough and that made no difference, which was weird because I was told ( and you indicate) it would kill the engine. But it doesn't kill it, it just keeps running. Could the fuel be going into 3 and 4? I now have a fitting I can t into the line and give the input pressure. I'll do that today. BTW, the company that rebuilt the pump has been very helpful and offering many suggestions. All of which I try and then post here. The offered to return my cost, but there are no new pumps available and they seem reputable. They replaced everything anyways, including the cam ring, housing and piston kit, so it is a virtually new pump.
Wow.. I wouldn't go as far as getting my money back!!! Did your pump come back w/ a BRIGHT orange/red tag attached to it?? TELLING YOU about loosening up the advance cap upon installation to get the air out of the pump..or serious pump damage will occur.. The threads on the return connector {checkball} are different than the fitting that screws into it, right? Seeing they're so nice, ask them to send you a "bad" 22109 return connector.. I wanted you to remove the checkball connector & "somehow" HOOK THE RETURN LINE BACK UP.. Basically, to flush the system out w/o the checkball in the way.. The pump didn't shut off because> the housing pressure has to be greater than inlet pressure.. you cant get that w/ your finger.. When you took the pump back the 1st time after the rebuild.. did they just put it on the test stand, do the checks & give it back to you?? OR did they tear it down, do an inspection & then recalibrate it?? If they replaced the cam ring & housing.. that means you had some SERIOUS contamination problems.!!! The contamination smashed the steel cam ring & rollers & wore out the advance piston & housing.. Did they TELL YOU THIS??
With a rebuilt pump and new injectors you're running out of possibilities. Is this all fresh fuel? Bio blend? How many hours on this engine again? Anything that affects the combustion can cause the higher temperatures, that's not nearly as helpful as it seems. Late timing, early timing, bad spray pattern, dribbling, not enough air, too much air. Peek into the intake manifold with a mirror? Boost pressure gauge? The two cylinders doing the same thing (you could confirm that by loosening the injection line when it's misfiring and see if either of them affect the roughness) is stranger, and therefor more helpful, potentially.
Oh, how I wish someone, anyone, had mentioned that inside of the fuel injector pump there is a small debris screen... More on this later.
You mean P# 28986?? THATS BECAUSE your not supposed to mess w/ the inside of an injection pump.. Even if that was the problem.. the time you took your pump back, they should have found it..?? THATS WHY I asked if they took it apart.. or just put it back on the test stand.. IF it was clogged, an "experienced" tech should have noticed it on the stand.. Heres hopin' you got it solved..
Furthermore, that screen is a last ditch emergency screen to protect the injection pump from gross contamination from a filter blowout, gunk that grew between the filter and the injection pump, or sloppy filter changes (filling the inside of the filter with fuel when changing). It shouldn't get anything in it ever in a regularly run and serviced machine. If it filled up twice, then something was wrong that should have been noticed on the filters, the inside of the lines, the tank, etc. This is entirely different from the screens on the intake to some transfer pumps that see anything that manages to get into the tank and through the hose, those screens are there to keep the valves in the transfer pump from sticking open and the engine not starting/running, as they are BEFORE the fuel filter and sometimes don't even have the water separator bowl and coarse screen between them and the tank that they were designed for.
Thepumpguy, you were getting close here, but not taking it apart depended on the rebuilder to DO HIS FRIKKIN JOB! Obviously they just put it onto the stand and it cost me around a grand in unnecessary parts. You would have thought... But after pressure washing the tank, really carefully flushing the lines and, installing new filters, this seemed improbable as the problem. Or so I thought. Here is the answer to anyone that has a reoccurring, maddening low power situation on a John Deere 710d (that incidentally even affects the hydraulics!). The fuel filter assembly was incorrectly plumbed FROM THE FACTORY! The inlet and the outlet were hooked inline and the fuel was bypassing the filter completely. This lead to tiny particles of contamination getting through the only filter, the sock in the fuel tank, making their way into he injector pumps filter and housing. These particles are really small, dust really. So they float around in the injector housing where, in normal use they don't build up enough on the filter to fully clog it, but do reduce the fuel flow to slightly reduce the power output. The engine runs perfectly at start up, and down a road where not much agitation is happening, or while using the backhoe, it runs ok, just low on power and weak hydraulics. But get onto a rough dirt road, or a high power situation and the engine starts to really run rough as the filter clogs from the dust being agitated inside the housing. So you shut it off, the fine dust falls off the filter and it repeats. So the new injector pump let it run perfectly for a while and then this situation began. If the injection rebuild company had taken it apart they would probably seen the dust, or perhaps not as the pump was drained of fuel out the nose and must of the dust would have washed out. So the pump runs well on their stand until I get it back and the problem resumes. So I buy a new John Deere pump and I have it sitting there and say screw it, as long as I have the replacement pump I'm going to take the old one apart. Voila... Dust. So I clean it AND install a second clear glass filter inline ahead of it. After a while of running I see this fine dust starting to build up in the clear filter. I clean all the lines AGAIN, but still see the dust. Hmmm. How the **** could the dust be getting by a 3 micron fuel filter??? So I take that spin on canister type ( the later style) filter completely off the tractor, take it apart, and find the filter housing was bypassed . Funny thing here, my old timer hates the new canister filters, said he just replaces them with the old square type. Makes me wounder just how many of them were plumbed wrong? So this explains why the tractor had such low hours ( it would have begun running poorly as soon as the tank got old enough to make rust) and was sold, why it passed a good short run time check out, only to work so badly for me. I can only speculate as to how this effects the hydraulics, but low engine power leads to low hydraulic power, even if the pressure is there, ESPECIALLY with a closed loop system where it destrokes the pump and gives the loss of flow! The tractor runs GREAT now. It is an animal, smooth, quiet, really efficient at moving large quantities of dirt. Now I need to remove the tank and POR-15 seal the inside to stop the fine rust particles ( even though the fuel filter now removes them) and I should be good to go. Thanks to everyone for their input
Glad you found the problem.. BUT.. Dontcha think it funny that a fella sitting infront of his computer, 1000's of miles away, can figure out what the problem is, with just a brief description?? & the people w/ the product IN THEIR HANDS cant.?? I guess that's why I'm a>> Master Injection Rebuilder.. & the rest are just "hacks".. Lol... I coulda used some of that 1000.00 you wasted.. its more like 1400.00 isn't it?? Probably 1200.00 for a new pump & 2-300.00 for a calibration check.. that they *** up.. Either way.. congrats on getting it fixed..
That is quite a journey you went on with your John Deere, Jay. The plumbing fiasco straight from John Deere when new is mind boggling. Congratulations on figuring it out.
To be fair to the rebuilder, today a new rebuilt pump showed up without my asking for it. Of course I called and thanked them, but also inquired whether they had opened up the nose to check the filter when it was sent back for the inspection. At least they were honest and said no. We had a long talk about that... I returned the pump unopened as the old one is now working GREAT!