Saturday, January 08, 2011

Diesel frustration...

I spent the day at FAR trying to get the diesel motor running.
I sent the following note and picture to the vendor I bough the generator from. Any ideas from the peanut gallery? I realize the text is kind of rough, but it is part of an ongoing conversation....



I've attached a picture with parts labeled.
I still don't have it running, so I'll explain.

Today:
First thing I did was fix the return plumbing on top of the injectors.
I did not end up replacing the injectors as when I got the new bolts it all sealed up.
The return line that goes from the right end of the injector string down to the filter was rubber and leaking so I replaced it with the new metal part
I got from you guys.

Between each step below I'm loosening the screws #B and pumping the little pump until I get clear fuel with no bubbles.
I'm treating screw B like one treats a brake bleed, you need to close it while clear fluid is coming out so it does not suck in air.

So after fixing that and priming and bleeding I try to run... nothing.

The I remove the left most injector line nut #A (shown removed in the picture)
when I crank no fuel comes out the empty fitting, nothing not even a drop.

Then I remove all four nuts, and nothing not even a drop from ANY of them.

I open cover #3 and lift up the plate and turn the motor over to make sure gear inside is turning. It is.

So one of the guys says diesel pumps have shear pins and that could be it.

So I remove panel #D and turn over the motor, you can see the plungers moving up and down so the shear pin is probably good.


At this point I text you.
So for the next step I remove the screws #2 and then unscrew the left most two fittings #1 and the one to the left of it.
Inside are little plungers and springs, the plungers may have been stuck but the are now free.

Then I reinstall the springs and plungers and turn the motor over (after bleeding) and noting comes out.

So I remove #1 again and manually operate the prime pump and fuel comes out.

If I only screw #1 in part way the prime pump can make fuel come out. IF I screw it in all the way the prime pump can't
make fuel come out. If I only put number 1 into the point that the prime pump can make fuel come out and crank the motor No fuel comes out.


A couple of comments
The Hose #10 is really stiff and too big for the nipple, I really can't keep it from leaking air.
All of the banjo fittings on the inlet side of the world seem to have non metalic seals that are dried out and leak.
These were some of the seals I asked you for, but I've removed #10 and the banjo fitting behind it and all the fittings going to the first fuel filter,
I've brought these home and I'm going to get new seals and new hose before I go back out.


Some questions:

So at this point I'm lost? The only thing I see that could be wrong is that the inlet check valve into the plunger pump assembly is stuck open?
At this point is seems like I'm down to a fairly simple concept" plunger pump and two check valves.
Where will I find the inlet check valves to unjam?
Can I remove the whole upper pump assembly #9, if so do I just remove the 4 nuts, or do I have to do something else?


#J is fixed and I'm guessing it should not be adjusted?

#H moves all the way counter clockwise when you try to start, I'm guessing that that is the ONLY shutoff the electronics has for the motor?

#C What is this and does it do anything?

It takes be 4 to 4 1/2 hours each way to go the the site.
I've now been to the site 4 times to work on the generator. not counting time on the phone at home or asking researching at home
I've spent close to 50 hours working on this what should I do next?

Did you guys actually run this motor at your office? (based on the way it was packed I'd guess no.)

So realize this motor has NEVER EVER EVER run, so what else could be wrong?

13 comments:

Anonymous said...

What was the understanding when you bought it? New, ready to run, refurbished, etc? Maybe that would narrow things down a bit. Does never run mean it is brand new and has never been run?

Paul Breed said...

Brand new, never been run.

Anonymous said...

I am the exact opposite of a guy who knows anything about diesel engines, and yet I once fixed one, almost by accident, on a cement mixer truck which was in a similarly non-operative condition. It was a clogged fuel filter. Blew it out with compressed air, and everything worked fine from that point.

I'm sure you know considerably more about diesel engines than I, but since I don't see "fuel filter" on the list of things that you've tinkered with, I thought I'd give it a mention.

dave w said...

OK, it sounds like you have the injector body filled with fuel but the plungers aren't pumping any out to the injectors. What you need to check now, I think, is the control rack mechanism. If that's the style of pump I believe it is, then each plunger has a little control sleeve around it, and there's a gear rack that moves lengthwise in the pump assembly and turns them all in unison.

Each control sleeve will have something like a little spiral groove that interacts with a "spill hole" on each plunger, so that once the plunger rises past the selected point, its outlet pressure is vented to the return path - this is essentially the "throttle" system that adjusts your fuel feed.

Normally there's a governor spring that pulls the rack toward the "open" position, and a centrifugal mechanism that pushes it "closed" as the engine accelerates to the desired speed. There's also usually an external cutoff mechanism that can push the rack "closed" - this is most likely what's happening with the lever "H" in your photograph (probably operated by a fuel cutoff solenoid not shown in the photo). So when you're trying to start the engine the rack should move to the "open" position and start feeding fuel.

My suspicion at this point is that the rack is stuck "closed" (perhaps by corrosion or gummed oil from sitting idle in the "closed" position), and so the injector isn't being commanded to deliver fuel even when it should (lever "H" to the run position and centrifugal governor at less than setpoint RPM -> should allow the governor spring to pull the control rack "open").

-dw

Stevo Harrington said...

From a management perspective, do you really need to be a diesel mechanic as well as a rocket scientist and computer genius?
I would hire someone to fix it.

Paul Breed said...

Next time we go to the site I'm going to get a Uhaul and bring it to a diesel mechanic. Its a Mjaor project to get it to a diesel mechanic. The road was too muddy to do it this time.

Mark Goll said...

Got glow plugs? The fire equation has not changed, heat, fuel, air. When my diesel gets cranky I check the glow plug connections. Trying to start a diesel without heat is dang near impossible. 2. fuel, is there diesel oil on the glow plugs? When the engine is spun with the plugs out does fuel spray out of the plug holes (full throttle please). 3. air, did somebody plug the air intake, is there suction when the engine turns over?

Mark Goll

Paul Breed said...

No plugs.
Yes we have air, no we don't have fuel. No fuel coming out of injector pump.

Anonymous said...

90% of diesel troubles are fuel filters

kevin smith said...

I am looking for a good mechanic for my car, those who have the excellent knowledge of diesel engine and proper repairing of it. Please suggest one...

diesel mechanic

xlpharmacy said...

I think, is the control rack mechanism. If that's the style of pump I believe it is, then each plunger has a little control sleeve around it, and there's a gear rack that moves lengthwise in the pump assembly and turns them all in unison.

Anonymous said...

Paul --

Did you ever put your 30kW genset into service ? Or did you have to buy something else completely ?

I have a condition here where I start genset and it runs for about 4 minutes and something energizes the stop solenoid and it comes to a normal stop. No red led comes on. The oil and coolant sensors do not change voltage on them when the solenoid stops everything. Its not really overspeed at 61 to 62 Hz.

I suspect I can pull the solenoid connector apart and it'll run til it exhausts the fuel, but that's obviously dangerous. I'd rather find the condition, if there really is one, that it feels warrants a shutdown. I cannot find any docs on my control, no schematic. Have you ever seen one?

Any thoughts?

Thanks, George

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