Stanadyne MFI pump clogged in M1025

[dohabandit]

I have a 6.2L 1985 HMMWV (got it back circa ~1999).

I have since swapped the engine and it ran well until recently.

Noticed the lift pump wasn't pushing much fuel so I replaced it and also replaced the fuel/water separator with a new unit and filter.
I also decided to install an inline filter right before the MFI pump because I saw that several iterations of civilian use GM 6.2's included this extra filter (usually connected to a bracket on the intake manifold).
Anyway, it looks like I have the air bled out of fuel lines (using bleed screw at separator top), but I am not seeing any high pressure fuel spray at injectors (lines are cracked loose on left side).
The fuel shutoff solenoid is "clicking", but I decided to open up the hat/cover and check the metering valve actuator. It was stuck. REALLY badly stuck.

I wiggled on it for a bit and it broke loose and started moving freely (hoping the armature just didn't separate from the valve shaft). I carefully re-installed the hat/solenoid cover (used a ziptie to pull the metal fingers back and hold them back while installing the cover, then cut the tie and slid it out side to release the finger actuator. If you haven't learned about this, don't learn the hard way! You can bend the actuator installing it improperly)
Tried cranking the engine some more and still no fuel delivery to injector nozzles. (solenoid is clicking with 54A) I filled the reservoir with some diesel kleen also hoping it might help to dissolve some sludge or whatever. It looked VERY CLEAN inside the pump though.

My guess is that the passage ways in the intake metering valve or the "delivery valve" are gummed up with varnish or something. (around the 06:48 mark in video below).
Does anyone have any experience with blowing carb cleaner/solvent through the MFI pump inlet?
Is it okay to just remove the fuel supply line and flood some carb cleaner into the metal inlet tube? (perhaps followed by some high pressure air to force it through those passageways?)
Can you force some carb cleaner from the top area around the fuel inlet metering valve?

I *REALLY* do not want to pull this MFI pump off. I have had to do that before and it was a major PITA. I ended up just replacing the pump in that instance (and the engine was later destroyed, long story. This is a new engine and pump.)
The process is fairly involved. Remove wiring harness, remove intake nozzle, remove intake manifold, install protective cover over open intake ports, remove steel fuel injector lines, remove cover on front of block, remove screws holding MFI pump gear, etc etc etc.

Any experienced MFI guys out there?

Nice video showing the basic pump design.
https://www.youtube.com/watch?v=veEONfhL3Uk

 

[dohabandit]

What about removing the top injector line and blowing some carb cleaner into it? Looks like it has a channel that goes by the fuel inlet control valve and it might drain down into the delivery valve area and unstick the valve?

 

[Wire Fox]

For what it's worth, I've been battling this same issue since around August. My engine was running great, didn't touch it for a month while I was working on my transmission install, then when I went to test it out, there was no-start, which turned out to be no fuel to the high-pressure side of the injectors, yet I had full fuel flow and pressure all the way to the injection pump. Both solenoids click fine, but haven't been able to properly test if something might be wrong with them regardless (though I've used two different top covers/solenoid sets). I've also purchased a different pump, cleaned and rebuilt that pump, then swapped it over and had all the exact same symptoms, though my clean/reseal may have been flawed. I've been at a loss, just as you have!

 

[gringeltaube]

................Anyway, it looks like I have the air bled out of fuel lines (using bleed screw at separator top), but I am not seeing any high pressure fuel spray at injectors (lines are cracked loose on left side). ...........................................
Tried cranking the engine some more and still no fuel delivery to injector nozzles. .........................

Keep cranking; it takes a good while to get all air out of the high-press side and have the injectors spraying again.
Much easier on the starter if you removed the glow plugs and covered-shut the air intake, also.

 

[dohabandit]

I got the pump working again. What worked finally was to remove the solenoid hat cover, remove all diesel fuel from the reservoir, break the armature free which appeared to be stuck.
Even with it freely moving for the inlet valve, it still wouldn't produce any high pressure fuel to the injectors.

I filled the reservoir with Seafoam (95% Naptha 5% ethanol) and let it soak for a month. After doing that, it fired right up after the 2nd attempt cranking.

Glad I didn't throw in the towel and remove the MFI pump to have it serviced.