6.5L N/A engine ran last fall, now no start. IP failure?

[Quack_Addict]

My issue is similar to bmiszuk's in a recent thread but my failure mode came on in a totally different manner. His truck died when he was running it and his problem ended up being a broken IP shaft - my truck ran great until I parked it last fall and now it won't even think about starting. I don't see how I could have broken the IP shaft simply by shutting the engine off last fall or trying to start it yesterday/today. My engine is a 6.5L naturally aspirated crate engine I got a deal on slightly used. The engine has approximately 40-50k miles on it since it was new.

Herer are my conditions, almost identical to bmiszuk:
1. The engine cranks fine.
2. I have fuel supply to the IP - good fuel flow out of the Stanadyne filter on the firewall when engine is cranking.
3. I opened the fuel injector lines on cylinder numbers 2, 3 and 5, removed the line completely from the injector. When cranking the engine, not even a drop of fuel comes out.
4. No smoke from tailpipes when cranking - no fuel getting thru the injectors, so no surprise here.
5. The shutoff solonoid clicks when the ignition is on and I pull the large pink wire (see photos). I also hear solenoids click when I pull the green wire and one of the wires on the coolant temperature sensor (also shown in images). I had to wire in the in-line fuse you can see with the orange wire - the previous wire insulation to the fusible link had deteriorated so I replaced it with a 20A fuse. I plan to get rid of the hack-job blue butt-splice by soldering & taping after I get the engine running again; it's a temporary fix.

How can I troubleshoot the injector pump? I can't remove the 3 screws on the top cover tonight; they are the tamper-resistant TORX screws and I need to borrow a bit for them tomorrow at work.

I have a spare injector pump off the 6.2L that was in the truck when I got it... will this interchange with my 6.5L naturally aspirated engine?

http://i49.photobucket.com/albums/f299/obkb2006/IM001959.jpg

http://i49.photobucket.com/albums/f299/obkb2006/IM001956.jpg

[john8662]

Couple of points first.

Yes, your 6.2 pump will work on the n/a 6.5, it won't know the difference. There is a slightly higher fuel amount with the 6.5 n/a injection pump though.

Second, don't bother trying to get a tamper resistant torx bit from work, the head on those bolts looks like a torx, but it ain't. The bit required is a proprietary bit made my Stanadyne, I already ruined a tamper proof torx finding that out on a core pump of mine. You can tell, take a normal torx bit out and count the spades, then count the points on the screw on the pump cover. Yeah, it'll make ya mad...

Anyways, I don't think that you're having a problem with the pump internal drive shaft being broken. I think this is a classic example of an "air lock".

First, get the fuel filter purged of air, I'm assuming you have the square Model 80 fuel filter holder. You'll use the top air bleed valve attached to some hose that ends in a plastic container for catching fluid. You want to bleed the air out of the fuel filter. You'll want fully charged batteries and a helper to get this right. After the air is out, close the valve on the filter housing. Once the air is purged, then you'll proceed to get the air out of the injection pump and system.

Go ahead and crack all 8 injection line nuts at the injectors. You'll want to once again charge the batteries up. Crank on the engine in 10 second intervals, letting the starter cool for about a minute or two between cranking sessions. By the third or fourth try, you should get some fuel weeping out the injection lines. Then tighten them all up, and you should be able to attempt to start the engine.

Sounds like you've checked the majority of the essentials, power to the solenoid, etc.

[Quack_Addict]

Anyways, I don't think that you're having a problem with the pump internal drive shaft being broken. I think this is a classic example of an "air lock".

John - I am pretty sure the IP isn't airlocked - I can't get a drop of fuel out of any of the injector lines with the injector nuts cracked a couple turns or even with the lines removed from the injectors all the way. I have cleared airlocks before and none have ever acted like this.

With the fuel outlet line from the fuel filter removed, I get great flow from the lift pump and through the filter. When I put the rubber line back on that connects the filter outlet to the IP, the lift pump actually builds pressure in the hose such that I get a little explosion of fuel when I take it back off after cranking the engine -- the lift pump is pushing fuel to the IP but the IP just isn't accepting the fuel and distributing it. It's almost like something inside the IP is plugged or broken - NOTHING is going through it.

I tried tapping on the pump lightly with a brass drift and a small hammer in an effort to dislodge anything that might be plugging an orifice or pop a stuck check valve back into place. Still nothing.

Any other ideas or suggestions before I make the run to the dealer for new intake gaskets and spend the time pulling the current IP and replacing it with the used 6.2L one I have in my garage? I have never heard of an injector pump just all of a sudden going bad. The truck ran awesome -- even made excellent power pulling a 3500 lb trailer -- right up until I parked it last fall.

[FredM]

did you take the fuel return fitting off, to see if you get flow?

[Quack_Addict]

did you take the fuel return fitting off, to see if you get flow?

I took the fuel return line off the injector pump, but not the barbed fitting it goes on. No fuel flow through return line with the hose removed and the engine cranking. I'm guessing this is bad?

[john8662]

Well, I thought I'd throw out how to make sure that the engine isn't airlocked..

You won't normally get any fuel out the return of the pump when just cranking.

Builing fuel pressure at the pump is normal IMO, you're supposed to have pressure at the injection pump. But, like you say, after it sits and has pressure is odd, like something is plugged.

Just to try, I'd suggest removing the fuel return valve in the top of the injection pump and swap on yours from the 6.2 pump. If this valve is plugged, you won't get any fuel either.

IT's looking like something could be wrong with the injection pump itself at this point. It's sure a bummer that your pump is one of the ones with the crappy screws on the cover, otherwise you'd be able to remove the top and take a look, and make sure the fuel shutoff linkage is in tact.

[Quack_Addict]

The 5-pointer TORX screws do add a bit of difficulty to taking the cover off, but I have the technology to get them out, if need be. ;)

I am surprised at how little information there is out there on Stanadyne DB2 injection pumps - I've been searching a good part of the morning trying to find a simple section view or exploded diagram. A troubleshooting guide? Yeah, right... It seems there's plenty of places out there willing to troubleshoot a DB2 for joe public, for a hefty fee of course.

In the section view of the pump I was able to find it shows an "inlet filter screen" behind the fuel line inlet, in the center of the 8 fuel injector line fittings on the back of the pump. Is this serviceable... guessing it could be plugged?

I plan on working on the truck again tonight after work - this will be my third and probably my last evening tinkering with this IP trying to get it to go before I tear it out and put in the one from the seized 6.2L engine. I'm pretty sure that pump works - the 6.2L it came off of ran well enough to spin 6 out of 8 rod bearings with it in there when the previous owner ran the engine without oil.

The funny thing is that with my luck, I'll end up swapping out the IP just to find out all the work was for nothing with a problem that still persists, only to find out the real cause was something stupid like a blown fuse.

[john8662]

I was thinking about that too, but the trouble is to get the fuel inlet, you're going to have to remove the intake anyways.

Looks like it's pump swapping time!

J

[Quack_Addict]

Finally SUCCESS - I got the truck running after swapping in the DB2 injection pump from the 6.2L engine that was in the truck when I got it. The engine runs pretty well but it has a miss on the left bank and blows white smoke out the left tailpipe after startup until the engine warms up a bit and I pedal it a couple times. This seems like air in one of the lines - I went through and cracked all the injector line nuts on the left side of the engine and it doesn't seem to make much of a difference the next time I start it up. I'm guessing it may be #1, all the air conditioning junk is in the way and it's hard to get on the line. I plan to troubleshoot the problem tomorrow.

Does the engine have to be retimed with the new IP installed? If not, why are the mounting holes in the back of the IP slotted? I'm guessing these slots allow the pump to be rotated until the bolts are tightened (similar to a distributor on a gas engine) to adjust the timing???

I have no clue what is wrong with the pump that was on the engine. When I first spun the shaft on it, fuel blew out the inlet on the back of the pump. I removed the nose that the inlet line goes into to check the filter inside and it is clean as a whistle -- not even a single speck of debris on it.

I'll have to see if I can track down the engineer at Stanadyne and thank him for putting the stud on the pump drive flange on the same bolt circle as the drive gear mounting bolts. Seems to me it would have been much better having the stud offset, at least that's my .02 after hitting the bolt hole with the stud no less than 6 times while installing the pump until I finally found the right hole.

[john8662]

As far as timing the engine, look at the pump mounting flange, you will notice a scribe line. The matching scribe line is on the timing cover in the "notch". You will align both of the lines, this is accomplished by loosening the three pump mount bolts on the flange and rotating the pump.

This will get you very close, the alternative is to use a timing meter, this will show you where to set the line.

Anyways, the slots on the back of the injection pump have nothing to do with getting the pump timed on the engine.

Glad that it's running.

Smoke out one side could be one cylinder not firing every time. I agree that the line under the A/C compressor is fun to get at!

I guess now you can get the top of the old pump off with some creative cutting right?

Let us know what you find!

J

[dieselbegreat]

People do sell frozen non-working IPs on eBay for use as returnable cores. They usually get from $25 to $50. Glad you got your motor runnin and thanks for updating us.

[Robyn]

Your 6.5 pump may simply had a problem with the fuel shut off solenoid.
After sitting they can fail to work. Been ther done that.