B7510 tries to start and smokes but won't run after a fuel filter clog---??? Help?

[MWeaver]

I got myself into a problem that has me baffled. My fuel filter gunked up after some months of very little use and I didn't notice, even though it had been getting harder to start. (Once started, it has always run fine. )

While I was running the tractor, it started surging and I tried to limp back to the barn, but the engine died and would not restart even though it was hot from running. I changed the fuel filter, drained the fuel tank and put in fresh fuel, bled the lines up to the injector pump intake (good flow) and then the bleed screw above the injector pump, bled the injector lines where they enter the cylinders. No start.

Eventually, I pulled the glow plugs and spun the engine to check that the injectors were getting fuel. Ragged at first, but after some spinning I got good mist out of each each port. Now, with the glow plugs back in, I can sometimes get the engine to cough and smoke and occasionally run on all cylinders for a second, but then it dies. I suspect gunk somewhere--but where? I am baffled as to the next step. Remove each injector line and check for obstruction? Could there be a return line problem? Other ideas? Anything it could be besides fuel supply? I am 100% baffled and would sure appreciate some help.

 

[North Idaho Wolfman]

Very common for the inlet or outlet of the Filter housing to get junk in it.
Make sure you are getting good pulsed flow to the injection pump.
If you have good flow go back and re bleed the injector lines.

 

[MWeaver]

Thanks, it is gravity fed through the filter to the injector pump intake. So no pulsing, but I have checked multiple times and lots of flow at that point. I am wondering if gunk could have gotten past the injector pump and into the lines that feed the cylinders, even though they are letting some fuel through when I bleed them. Otherwise, I am lost for ideas.

 

[Russell King]

I assume that some gunk could have grown in the injector lines. You can remove them and clean them out. Just be sure to use a backing wrench on the injection pump parts that you don’t want to turn when breaking loose the lines. I think that is a low probability problem but easy enough to eliminate.

Just remember that you can also see how much fuel the injector pump is moving while the lines are removed, I think it is called a fountain test.

Bleed all the lines again when you get it back together and hopefully it will start. Just bleed them more than you think is necessary.

 

[MWeaver]

Thank you Russell, agreed, I will try removing and checking/cleaning the injector lines and return line, plus the fountain test of the injector pump while they are off. I simply cannot imagine anything it could be besides fuel starvation near the cylinders.

If stuff was growing in the lines, maybe that would explain why it was progressively more difficult to start over the last few months?

 

[North Idaho Wolfman]

Thanks, it is gravity fed through the filter to the injector pump intake. So no pulsing, but I have checked multiple times and lots of flow at that point. I am wondering if gunk could have gotten past the injector pump and into the lines that feed the cylinders, even though they are letting some fuel through when I bleed them. Otherwise, I am lost for ideas.

Ummm no, it's not gravity fed, there is a lift pump.
So if your not getting pulsed fuel to the injection pump while cranking you have an issue!

 

[MWeaver]

Wolfman, You are totally right, sorry, this thing wore me out yesterday and my brain was fried.

The intake to the lift pump is where I had good gravity flow, but a helper did check the lift pump outlet while I cranked and said it was absolutely spewing fuel, so I didn't see the pulsing but I do think that the lift pump is working. Tomorrow I am going to remove the injector lines, make sure they are clear, and see what the injector pump is producing at the outlets when I crank. I guess at this point I am hoping to find some crud in the lines so I can at least see a cause for the no-start problem.

I really appreciate your input. I don't have enough experience to be confident in what I'm doing, and I have the feeling there are probably clues that I am missing. So if you are willing to keep commenting, I will very much appreciate it.

 

[Runs With Scissors]

I have no useful info to add to the troubleshooting, but one thing that seems to be a common thread in many “crank, no start” situations is the use of “starting fluid”.


As a new member, I don’t know how much “diesel experience” you have, so this is just an “FYI”.

NEVER….EVER….NEVER use it on Kubota motors….

I add this comment becasue I have seen more than my fair share of guys that think using “Just using small whiff” will be ok…….but it ain’t.

Catastrophic damage will occur if it is used……..(even in 'teeny tiny’ amounts)

Carry on gentlemen…….

 

[PoTreeBoy]

Wolfman, You are totally right, sorry, this thing wore me out yesterday and my brain was fried.

The intake to the lift pump is where I had good gravity flow, but a helper did check the lift pump outlet while I cranked and said it was absolutely spewing fuel, so I didn't see the pulsing but I do think that the lift pump is working. Tomorrow I am going to remove the injector lines, make sure they are clear, and see what the injector pump is producing at the outlets when I crank. I guess at this point I am hoping to find some crud in the lines so I can at least see a cause for the no-start problem.

I really appreciate your input. I don't have enough experience to be confident in what I'm doing, and I have the feeling there are probably clues that I am missing. So if you are willing to keep commenting, I will very much appreciate it.

I'd go back to the lift pump. 'Spewing' sounds like it may be pumping air in via a broken diaphragm. You can temporarily gravity feed the injector pump to check.

 

[MWeaver]

Thank you all,

After calm(er) reflection, I think I am going to go back down to the fuel tank line, test the flow there, and work my way through the filter housing, (as Wolfman suggested), and up to the lift pump, making sure each piece is clean and functioning properly. Then a fountain test.

And yes, Runs With Scissors, I NOW know starting fluid is NOT to be used, but before I learned this, I used it a few times in small amounts last winter The engine ran fine afterward--but could I have damaged something that is now causing problems? I could use some guidance here, as I don't really understand what exactly the risk is.

I should probably add that when the engine now coughs and starts to run for a second or two, it sounds fine--like it is cruising on all three cylinders--it just won't keep running. That is why I am focusing on fuel supply.

 

[#40Fan]

Starting fluid had crack/break a piston, bend a rod, which would make it run poorly or hardly start due to low compression. If you're saying that runs good when it does, I am sure you don't have a problem there.

Won't the fuel pump run with just the key on? If so, you should be able to check flow from it without the need for another person.

 

[Workerbee]

Won't the fuel pump run with just the key on? If so, you should be able to check flow from it without the need for another person.

According to the parts diagram wolfman posted thats mechanical pump, so having the key on is irrevelant

 

[MWeaver]

Thanks for your reply, I feel a little better knowing that maybe I have not trashed the engine.

The lift pump I think is cam-driven, not electric (no wires). I have short-circuited safety switches and jammed the clutch down so I can sort of peer at the engine and (almost) reach around and turn the key at the same time. I am about to go out and start beating on the beast and will report progress/or lack thereof in a few hours.

 

[MWeaver]

PS--I am truly grateful for all your replies, as I am quite a ways out in the boonies in western Oregon and not a lot of help nearby-- few neighbors and nearest gas station/parts source is 40 miles. As the tractor is my firewood fetcher, it is more or less responsible for heating the house, and life becomes quite a scramble without it.

So THANKS, y'all. Will update after the next tests completed

 

[Russell King]

I just realized you said it “smokes” but won’t run in the title and the first post.

Can you describe what color the smoker is and more about how it smokes. Does it spit out black smoke while cranking? Grey smoke as it first starts…

That kind of detail may point to some problems that we haven’t discussed at all.

See this site for what the different colors mean to a diesel engine.

Diesel Smoke Diagnosis Guide - White, Grey, Black, Blue - learn diesels

We are going to cover the main types of diesel smoke and the causes in this article. If you are […]

learndiesels.com

 

[PoTreeBoy]

Thanks for your reply, I feel a little better knowing that maybe I have not trashed the engine.

The lift pump I think is cam-driven, not electric (no wires). I have short-circuited safety switches and jammed the clutch down so I can sort of peer at the engine and (almost) reach around and turn the key at the same time. I am about to go out and start beating on the beast and will report progress/or lack thereof in a few hours.

I'm pretty sure on that model you can bypass the lift pump if the tank is nearly full. At least for a test.

 

[#40Fan]

According to the parts diagram wolfman posted thats mechanical pump, so having the key on is irrevelant

My bad...I should have looked closer at the diagram.

 

[MWeaver]

Update: Possible cause found (!?) and some new questions :

I might have the located the culprit, with particular thanks to several of you who were suspicious of the lift pump despite my assurances. After cleaning everything up to the lift pump intake, and disconnecting the outlet hose from the lift pump, I let the supply hose fill from the filter up, connected to the pump inlet, and spun the engine expecting to see diesel flying out of the pump outlet--or at least spurting. Got a few bubbles--and a lot of nothing.
I assume that with the hoses full and good gravity feed, it should not take more than a few seconds for the pump to start spitting out fuel?? I cranked it for about 10 seconds at least 3 or 4 times and was astonished to find nothing coming out.

So two more Qs:

1. I will test again when my battery and starter have calmed down, but if someone can tell me what lift pump spurts SHOULD look like--More than a drip? Squirty and pulsing with some pressure if you hold your finger against the outlet hole? etc., I will have a standard to judge by.

2. Another question--Is it REALLY ok to bypass the fuel pump and just run the gravity feed straight to the injector pump and try to start ithe tractor? (Sorry, I know several have suggested this but I am short on experience and afraid of damaging something) ..
And if it starts, will it run that way (w/o damaging anything) for a few minutes??? I would like to move the tractor out of the mud puddle it has been living in since it broke down. It would be a lot easier to work on if I could get it to dry land!)

 

[North Idaho Wolfman]

It should pump fuel almost immediately.

Yes you can bottle feed the injection pump, just make 100% sure fuel is very clean.
You more than likely will have to bleed the injectors again.
On that model pump you will need to temporarily crimp off the vent line or the gravity fed fuel will just end up back in the tractors tank.
And yes you can run it for as long as it's getting fuel to the pump.

 

[MWeaver]

Re Crimp the vent line --there is a tiny rubber hose that comes off the injector pump inlet and goes up to the injector row--is that the one you mean?