Injector Pump Question

History:
-Have had HMMWV for about 6 years, ran fine (with repairs and maintenance). Did not start it for almost 2 months. Vehicle had 1/4 tank of older fuel. Will not start now.

Current symptoms:
-No fuel expelling from exhaust on cranking. Not starting.
Note: Glow plugs working normally, new batterys installed.

Actions taken:
-Tank drained and dropped. Fuel sock replaced. Fuel level sender replaced. Tank cleaned (newer tank, not particularly dirty). Tank filled to 1/3rd.
-Fuel filters replaced.
-Fuel filter outlet hose to injection pump checked, pumps fuel normally.
-Injection pump return hose checked, flows while cranking.
-2 Injection pump outlet lines checked, barely flows at all.
-Multiple injectors cracked, barely flows at all.
-Tested 2 solenoid connectors on injection pump with ignition on, front wire shows 20+ volts and other wire appears to be ground.

Originally thought that the fuel level had gone too low or vehicle was not used long enough so it must have lost prime.
Fuel seems to be making it to the IP, but is not flowing out to the injectors (even if cracked).

Question:
Should both leads connected to the solenoid on top of the injector pump be positive at 24v when the ignition is turned on, or is one a negative lead? (Smart box issue?)

Note: I marked what I'm seeing for both connectors at my solenoid on a page from the manual.

I've tried pressurizing the tank a little while cranking to get fuel up to the IP, which appears to work.
Now I'm trying to decide whether all injectors need to be cracked to expel air (tough accessing some of them), or if the solenoid is possibly the culprit.

Pull a glow plug and see if it is wet with diesel. Are your plugs working? I doubt it's the fuel quality, unless it has water in it. If it resembles diesel, it will most likely work, even if it's old. If your IP is working, you will get about a drop when you crack the line and crank the engine. Remember, this is being injected into the engine at high pressure so it is a very small, metered quantity. Don't expect to see diesel "flowing" out of the injector lines.

Dieselmeister said:

Pull a glow plug and see if it is wet with diesel. Are your plugs working? I doubt it's the fuel quality, unless it has water in it. If it resembles diesel, it will most likely work, even if it's old. If your IP is working, you will get about a drop when you crack the line and crank the engine. Remember, this is being injected into the engine at high pressure so it is a very small, metered quantity. Don't expect to see diesel "flowing" out of the injector lines.

Click to expand...

Plugs are fully functional. Installed a momentary manual system due to dumb box malfunction a while back. Everything worked fine for a number of years. When the glow plugs were not working before there was a strong fuel vapor emitted from the exhaust after cranking for a bit. There is no fuel coming from the tailpipe now.
Thinking about pulling all glow plugs as a way to check that cylinders are receiving fuel.

ikoinu said:

I've tried pressurizing the tank a little while cranking to get fuel up to the IP, which appears to work.
Now I'm trying to decide whether all injectors need to be cracked to expel air (tough accessing some of them), or if the solenoid is possibly the culprit.

Click to expand...

pressurizing the tank and then crack all the injectors one by one to bleed off any air sounds like a good idea to me. If you can get it started then and it runs like crap you may have to bleed them some more.

ikoinu said:

History:
-Have had HMMWV for about 6 years, ran fine (with repairs and maintenance). Did not start it for almost 2 months. Vehicle had 1/4 tank of older fuel. Will not start now.

Current symptoms:
-No fuel expelling from exhaust on cranking. Not starting.
Note: Glow plugs working normally, new batterys installed.

Actions taken:
-Tank drained and dropped. Fuel sock replaced. Fuel level sender replaced. Tank cleaned (newer tank, not particularly dirty). Tank filled to 1/3rd.
-Fuel filter drain checked, fuel comes out.
-Fuel filter outlet hose to injection pump checked, pumps fuel normally.
-Injection pump return hose checked, flows while cranking.
-2 Injection pump outlet lines checked, barely flows at all.
-Multiple injectors cracked, barely flows at all.
-Tested 2 solenoid connectors on injection pump with ignition on, front wire shows 20+ volts and other wire appears to be ground.

Originally thought that the fuel level had gone too low or vehicle was not used long enough so it must have lost prime.
Fuel seems to be making it to the IP, but is not flowing out to the injectors (even if cracked).

Question:
Should both leads connected to the solenoid on top of the injector pump be positive at 24v when the ignition is turned on, or is one a negative lead? (Smart box issue?)

Click to expand...

++++++++++++++++++++++++++++++++++
Peeking over your shoulder...

Parked for a couple of month ?
Older fuel ?

Will not start now. IMO this can be something to consider. The bio-mixed diesel with 5-25% crap, low sulfur, lubricants and any water (there is some water ) to make a blend of a biological mix to harbor the dreaded DIESEL BUG. The filter/s can catch the big parts, But the little ones are flowing, modifying the fuel. It can smell funny and it will gum up the IP metering valve. This is a small and precision, controlling fuel deliver and shut off. If stuck one is... rhymes with ________ed.

You stated voltage. All things correct and normal, 20 volts (a bit low, double check test / batteries) should pull in the shut off solenoid allowing the metering valve to open (run) and fuel to flow when cranking engine over. Also the other connector at the rear is the cold advance. It will have 24 volts when engine is a first time start or cold.

Opening a injector hardline one would expect to have a very small amount of fuel showing up, small. ( I place a clean white rag between injector and hardline feed. After cranking five or six times should have a 2-3 inch blotch spot, not much but noticeable. Not a flow, no squirting.

IMO Stated fuel flowing with some pressure? towards IP input. There is a input filter, But it would and could be clogged up, to be considered, but not likely with quality filtering down stream. What kinda run time on IP ?? abuse, worn out tired?

Not a start box issue. Famous for all problems HumV, ask me. Having the voltage to the IP shut off solenoid AND hearing the clicking test and IP hasn't been jacked with, working before? OK.

MY guess is pointing too, but could be, maybe, inline with crap fuel and not driven enough to keep free from the "dreaded diesel bug."

Think of it like Covid for the HumV. Google search DB2 pump and operation. Diesel fuel storage and additives and medicine for the BUG. Biocide.

YMMV, CAMO

thompsoncustom said:

pressurizing the tank and then crack all the injectors one by one to bleed off any air sounds like a good idea to me. If you can get it started then and it runs like crap you may have to bleed them some more.

Click to expand...

Thanks. Was just trying to figure out if there was another obvious issue so I wasn't pissing in the wind cracking injectors (some of them are a right PITA to get to).
Time to start pissing in the wind

ikoinu said:

Thanks. Was just trying to figure out if there was another obvious issue so I wasn't pissing in the wind cracking injectors (some of them are a right PITA to get to).
Time to start pissing in the wind

Click to expand...

If you disconnect and connect the wire #54 at the front of the IP do you hear the solenoid click inside the IP?
The other wire is the cold advance, working or not the engine should still start.
Just keep trying, sometimes the plungers in the IP get stuck, good hot batteries and a fast cranking speed are your friend as the more pressure the transfer pump in the IP can make the better the odds your will move the plungers in the IP.

Milcommoguy, the metering valve is clicking and getting 20+ volts, do you think it could still be clogged up? Should I pull it and run it through a sonic cleaner?

Not sure on IP run time. The vehicle is an 88, I put 16k on it myself for a grand total of 32k on the odometer (this odometer at least Purchased from a dealer who got it from the auction and ran it for a while, mileage is legit on the civilian side but who knows about the military. Was starting and running great until it stopped. Diesel was almost 4 years old, but is pushing hard out of the water separator so good flow.

When something is wrong I always look suspiciously at the stupid-box, but you're right this is definitely a fuel flow issue.

Will do.

Mogman said:

If you disconnect and connect the wire #54 at the front of the IP do you hear the solenoid click inside the IP?
The other wire is the cold advance, working or not the engine should still start.
Just keep trying, sometimes the plungers in the IP get stuck, good hot batteries and a fast cranking speed are your friend as the more pressure the transfer pump in the IP can make the better the odds your will move the plungers in the IP.

Click to expand...

Did not try disconnecting and reconnecting #54 (front wire on the IP). Had felt it when the ignition is turned on and off and it does click. Should be good?

ikoinu said:

Did not try disconnecting and reconnecting #54 (front wire on the IP). Had felt it when the ignition is turned on and off and it does click. Should be good?

Click to expand...

That should be OK.
You never said you replaced the filter, it is of utmost importance to maintain a very clean filter or the lift pump can push crap past the filter and plug up the IP.
I never cared for canister filters, when I started as a mechanic many types of equipment and autos had canister filters, there is a reason they have fallen out of favor, even IF they are correctly assembled which happens much less that one would think, if they get plugged they have a tendency to allow trash to go around the end seals.
This is not so with spin on filters unless they have a by-pass valve.

If your filter is not complete including the water separator then it will not seal off the end seals at all.
You cannot clean the IP in a sonic cleaner, it is much too complex for that to work.

ikoinu said:

Milcommoguy, the metering valve is clicking and getting 20+ volts, do you think it could still be clogged up? Should I pull it and run it through a sonic cleaner?

Not sure on IP run time. The vehicle is an 88, I put 16k on it myself for a grand total of 32k on the odometer (this odometer at least Purchased from a dealer who got it from the auction and ran it for a while, mileage is legit on the civilian side but who knows about the military. Was starting and running great until it stopped. Diesel was almost 4 years old, but is pushing hard out of the water separator so good flow.

When something is wrong I always look suspiciously at the stupid-box, but you're right this is definitely a fuel flow issue.

Will do.

Click to expand...

Click is solenoid pulling in. Doesn't mean metering valve is free.
Study the DB2 pump operation > https://media.defense.gov/2014/Jun/20/2002655917/-1/-1/1/140620-N-ZZ182-6558.pdf

There could be one or a chain of little issues to resolve any problem. Poking around for a quick fix might not happen. Follow the fuel with logical steps like you have. Process of elimination, test and next step. Got fuel to the pump? Next, want fuel out? Sounds simple enough. IP is a complicated, precision device.

Hearing of 4 year old California fuel raises my ears. Did truck run... hick up and stop? Red herrings and rabbit hole testing on anything, likely won't get good results. Adds to the story... so turn the page. Old fuel, pushing out hard says lift pump is working.

A little more digging deep, Tiger. HumV's don't have feelings. SO use logic. I am pointing a finger to the IP. That's my guess from the text. LOL

SO... What's really in your tank? CAMO

Took a look into the top cover of the HP Pump today.
It was filled with fuel, quite clean inside. Everything appeared to be working as it should on top, including the Fuel Shutoff Solenoid and the Cold Advance, demonstrated in the video.

Now, I have not messed around with a brand new one so might be missing something? Looking to avoid pulling the pump if at all possible.
Hopefully the issue is just air in the lines to the injectors (rather than a dead HP Pump).
Will be bleeding these again, more thoroughly this time.

HP Pump Throttle Action
Fuel Shutoff/Cold Advance

I'm no expert on the IP but in your video and pictures my opinion it looks like the metering valve is all the way back stuck in the closed position similar to how when the top cover is on, and the fuel cutoff solenoid pushes the valve in that position till it receives 24 volts to close and allow metering valve function.
Should be some spring action when you push on the part and release that the top cover switch makes contact with.
I would exercise the linkage part I circled back and forth this is what the top cover fuel cutoff solenoid holds back until energized it should return to that position without the cover switch holding it in what looks like in your video and pictures the off position.
Also, careful putting that cover back on that you don't pin that lever forward in the open position if the engine does start that way you won't be able to stop it causing a possible runaway condition.

Jyg101 said:

I'm no expert on the IP but in your video and pictures my opinion it looks like the metering valve is all the way back stuck in the closed position similar to how when the top cover is on, and the fuel cutoff solenoid pushes the valve in that position till it receives 24 volts to close and allow metering valve function.
Should be some spring action when you push on the part and release that the top cover switch makes contact with.
I would exercise the linkage part I circled back and forth this is what the top cover fuel cutoff solenoid holds back until energized it should return to that position without the

Click to expand...

Great suggestion!!!! Thank you.
The lever that the Fuel Shutoff Solenoid actuated was frozen. Once I worked it back and forth, it moved freely again. This was also suggested on another discussion, but not having looked at a properly functioning system I did not want to break a part by forcing it.
-Is the spring action supposed to be strong, or weak? Mine is pretty weak. Video Link attached of the lever working
I will have to bleed out the system again and see if that fixed the problem.

-When reassembling the top cover, the actuator from the solenoid (circled) goes in front of this piece (where the arrow is pointing), correct?
It looks like it should fit around it with the piece inside, but the solenoid can not move anything if it is assembled like this.

Fuel Solenoid Lever Action

Let me go look, now you have me wondering.

Thanks. So the tab goes in the metal actuator from solenoid, or the actuator goes just in front?
It's tough because you can't actually see how it fits when you pull it apart.

Yes you are correct on the tab,I was wrong, you start with the front of the cover down on the pump as you slide the cover forward and down as the solenoid will allow you to until it drops in.
If you have it correct if you slide the cover forward you will feel spring tension pushing the cover back.
I think some use a makeshift tool to hold that tab forward in the no fuel position while putting the cover in position.

Not your exact setup but the solenoid lever is in the same place in reference to the tab.

This is the no fuel position, as you see if you slide the cover forward you are compressing the solenoid spring which is holding the linkage in the no fuel position.
If you slide the cover forward and do not feel spring tension it is not correct.

Mogman said:

Let me go look, now you have me wondering.

Click to expand...

ikoinu said:

Great suggestion!!!! Thank you.
The lever that the Fuel Shutoff Solenoid actuated was frozen. Once I worked it back and forth, it moved freely again. This was also suggested on another discussion, but not having looked at a properly functioning system I did not want to break a part by forcing it.
-Is the spring action supposed to be strong, or weak? Mine is pretty weak. Video Link attached of the lever working
I will have to bleed out the system again and see if that fixed the problem.

-When reassembling the top cover, the actuator from the solenoid (circled) goes in front of this piece (where the arrow is pointing), correct?
It looks like it should fit around it with the piece inside, but the solenoid can not move anything if it is assembled like this.

Fuel Solenoid Lever Action

View attachment 933536View attachment 933537

Click to expand...

Yes it goes in front of that tab you will know you have it correct when you push the cover slightly back it will spring forward try a few times to get the feel before you do the final install.