Hard/no start when sitting/cold - 2000 F250 7.3

[greenskeeper]

Otoh, tests have been run to show once you're moving, IAT with a 6637 is very close to ambient. If running a intercooler it's a moot difference even more so.

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agree....biggest downside to the 6637 is intake noise...some like it...some don't....I couldn't stand it so I went back to the factory air box

 

[Macrobb]

Finally got a chance to post a video:

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First start, from before I posted this topic.

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So, at this point, I'm fairly convinced that all 8 glow plugs are working. I went in and tested the other four, checked the harness, and installed a new relay. Still... nothing. Tries to fire on two cylinders, but nothing more than that.

I'm thinking... injectors. I'm getting a /little/ smoke when cranking, and slightly bigger puffs when it tries to fire... I'm thinking the other cylinders just aren't getting any fuel.

Based on my research, I may be able to just re-shim the (worn out) injectors and get some more life out of them. We shall see.

I also may swap injectors with the (worn, but still viable) injectors in my friend's '97 Cali truck(so those injectors are also split-shots, just slightly less CCs than the ones I have).
But, as those injectors made 280 RWHP with the 'tow' tune on his truck, that's still enough fuel.

 

[greenskeeper]

Did you ever replace the glow plugs with NEW ?

 

[Macrobb]

Did you ever replace the glow plugs with NEW ?

No, and I won't, unless they fail some test. I don't just throw parts at something. I have a full set to replace them with, BTW - but if they don't go in this motor, they will go in something else.

I did test a couple side-by-side with new motorcraft plugs, and had very similar results; I can also tell by the spark size(when hooking them up cold) that several that I didn't pull and check are working the same as the one I did.
And yes, I actually did go back and pull one, hook it up to a battery, and watch that the entire GP tip turned red within 10 seconds. It honestly was a little faster than that.
This is, IMHO, as good as any new IDI glow plug ever does.
I even tested one hooked into the harness itself - so glow plug, pulled from the motor, plugged into the GP harness and held grounded while my friend turns the key on.
And yes, it got similarly hot as hooking up to the battery directly.

However... the fact that this motor will sit there and run on ether alone, but won't take off, at least not for a while... That's not something I've seen with other diesel motors, if they are getting fuel into the cylinder. Which brings me back to the smoke issue - I'm wondering if about 5-6 injectors are not firing when it's cold.
Judging by the age of the injectors(~230K) and everything I'm reading says that around this point, this will happen... It's a likely candidate.

Now, this seems like one of two cases: HPOP wear resulting in low pressure, or injector poppet wear... resulting in firing issues and possibly low oil pressure. I haven't ruled out either, but hopefully I can by swapping injectors, or checking the gap on the armature plate(and then shimming to correct it).
See:

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[79jasper]

The hpops don't really wear/fail like ip do. Imo, injectors are a place to start. I've seen other 7.3's with great gp systems not start in 70 degrees unless plugged in to warm the injectors.

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[u2slow]

The hpops don't really wear/fail like ip do. Imo, injectors are a place to start. I've seen other 7.3's with great gp systems not start in 70 degrees unless plugged in to warm the injectors.

Hpop's either lose output pressure or lose prime somehow with age/wear/tear. I say this because changing mine to another used unit improved cold-starting remarkably. The old hpop would not build pressure in the oil rails when the engine was cold. (Plumbed in a mechanical pressure gauge.) I can't emphasize enough how valuable this sort of gauge is for troubleshooting.

That said, not ruling out injectors... but mine did perform within a few seconds of the gauge beginning to flicker - whether the old hpop or the 'new' used one.

IIRC, glow plugs pull about ~18amps each. If you are seeing 100+ amp draw when the solenoid pulls in, you have enough working for reliable starting.

 

[79jasper]

Right, definitely not saying they don't, it's just rarer. More often the anti drain back valve fails.
If replacing, I would for sure do a bigger/upgraded one. I did a stage 1 17° back when cnc was still dealing mb diesel pumps.
A mechanical gauge can help immensely.


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[u2slow]

Right, definitely not saying they don't, it's just rarer. More often the anti drain back valve fails.
If replacing, I would for sure do a bigger/upgraded one. I did a stage 1 17° back when cnc was still dealing mb diesel pumps.
A mechanical gauge can help immensely.

The drainback valve failure results in the hpop reservoir going dry after the engine is off, right? Mine would only run empty from long cranking. Didn't matter if it was the stock lpop, or the Melling high-output I replaced it with. The hpop depleted the reservoir faster than the lpop could refill - somehow - without pressurizing the rails.

I did go from a stock '97 hpop to a used '99 unit (17 degree). The IPR got changed too, which may be a further factor.

 

[79jasper]

Yes, usually after sitting overnight.
Your case is a odd one. Even with the hpop at max commanded psi, it shouldn't drain the reservoir. Maybe a weak lpo pump.

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[u2slow]

However... the fact that this motor will sit there and run on ether alone, but won't take off, at least not for a while... That's not something I've seen with other diesel motors, if they are getting fuel into the cylinder. Which brings me back to the smoke issue - I'm wondering if about 5-6 injectors are not firing when it's cold.
Judging by the age of the injectors(~230K) and everything I'm reading says that around this point, this will happen... It's a likely candidate.

The fact you're getting some intermittent firing before it catches tells me you have sufficient hpop pressure and fuel pressure (at least on one bank) because those are fed into common rails in each head. If you remove the check valves from the hpop, you make the pressure between the heads common too. That change can make things better or worse, but helps you isolate the 'problem' side. This would be a nice time to have that hpop gauge.... you can see if its struggling to make base pressure (~500psi IIRC). The IPR can be dumping off your hpo pressure too. (significantly cheaper than injectors)

What are you getting for smoke? (if any?) A dribble or stream of fuel from the injector won't light easy like a fine spray will. But it will make thick white fog when the engine finally catches. I'd wonder though if the ether has the ability to burn off the residual diesel as it tries to run on the ether alone.

Supposing you have gummed-up injectors, heat (block heater) may be introducing enough thermal expansion to free them. The heat could also make o-rings seal better. I've heard ATF in the fuel, or other fuel/oil additives can help there (Seafoam? XM-5?) There's also the possibility a fresh or performance hpop will have the extra punch to fire an otherwise sticky injector.

I don't think you can go wrong with injectors at that age/miles. It just may not be the whole picture.

Found this link for an o-ring test. Looks like there's enough fitting size info there to get a hydraulic line and gauge installed.
https://www.ford-trucks.com/forums/1580266-hpop-and-injector-o-ring-test-kit-diy-style-2.html

 

[greenskeeper]

No, and I won't, unless they fail some test. I don't just throw parts at something. I have a full set to replace them with, BTW - but if they don't go in this motor, they will go in something else.

I did test a couple side-by-side with new motorcraft plugs, and had very similar results; I can also tell by the spark size(when hooking them up cold) that several that I didn't pull and check are working the same as the one I did.
And yes, I actually did go back and pull one, hook it up to a battery, and watch that the entire GP tip turned red within 10 seconds. It honestly was a little faster than that.
This is, IMHO, as good as any new IDI glow plug ever does.
I even tested one hooked into the harness itself - so glow plug, pulled from the motor, plugged into the GP harness and held grounded while my friend turns the key on.
And yes, it got similarly hot as hooking up to the battery directly.

However... the fact that this motor will sit there and run on ether alone, but won't take off, at least not for a while... That's not something I've seen with other diesel motors, if they are getting fuel into the cylinder. Which brings me back to the smoke issue - I'm wondering if about 5-6 injectors are not firing when it's cold.
Judging by the age of the injectors(~230K) and everything I'm reading says that around this point, this will happen... It's a likely candidate.

Now, this seems like one of two cases: HPOP wear resulting in low pressure, or injector poppet wear... resulting in firing issues and possibly low oil pressure. I haven't ruled out either, but hopefully I can by swapping injectors, or checking the gap on the armature plate(and then shimming to correct it).
See:

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.....$80 in glow plugs versus tearing into the injectors and HPOP......priceless.

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[SebastIDIan]

.....$80 in glow plugs versus tearing into the injectors and HPOP......priceless.

You must be registered for see images attach

Only thing that has me second guessing GPs is that it fired and then died. I doubt bad glowplugs would cause it to die after running for some time

 

[Macrobb]

The dying while running thing... that's only happened once... when I had my cheap OBD2 adapter plugged in, and new PIDs(which didn't work, BTW) set up. I haven't plugged in the OBD2 adapter... and haven't had any more issues like that. I need to try again, though, or I can't check ICP pressure or anything.

Also, I think I'm on the right track. Today, my shim kit came in. It was a bit rainy today, but I set up a tarp and did one bank(driver's side) anyway - Just went ahead and put a .004" shim under the armature, and .002"+.003" shim under each screw.
And yeah, near as I could tell, they all needed it. I didn't have a feeler gauge set handy, but using a couple of shims as feeler gauges, I was well below .004 on all that I checked. And saw evidence of rubbing between the bottom edge(outboard/lower) of each injector's armature plate and the injector body underneath it. Which means that there was *not* a gap between them at some time.

Put it together... and after hooking up my other truck to jump it because it may just have a battery drain and the batteries were low... she tried to fire a /lot/ more. Figure about 2x as many cylinders firing as before.
Not enough to start, but more than before.
I'm guessing at least one of the injectors on this side was the one that was 'working' when cold - because #2 has a different color solenoid(yellow vs brown), so I'm guessing it's newer than the rest. How *much* newer... I don't know. It still barely fit a .002" shim at the bottom.

But, still, Progress!

Also, I have to say - getting into injectors and shimming them is honestly not hard, especially with an impact driver. It made all those torx screws and the reverse torx *so* easy. Total project took me ~2 hours from pulling my tools out to putting them away.

 

[79jasper]

Some cheap obd2 adapters will cause the shutoff. Sometimes it's settings in the app.

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[Macrobb]

Problem solved! (I hope for good)

Finished shimming, go to start, and...

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However... Now the oil cooler is leaking, and pretty badly. Time to deal with that.