No-Start Condition

[Wire Fox]

I'm getting close to stumped here... my engine was a strong runner a couple months ago. I hadn't run it for a while as I was working on getting my 4L80E ready for use. Forward to a few days ago, it won't start. My glow plugs cycle for 8 seconds (S3) and warmth can be felt on the block at the plug, I crank and the engine spins and I hear compressions as it spins around, and I see cold, white smoke in the exhaust.

I removed the air filter and found no restrictions, so reinstalled. My fuel was getting old, so I dumped it all out and put in 5 fresh gallons of diesel. Before attempting a start, I cleaned the filter housing, changed both filter elements, and bled the system. I also put on 4 fresh batteries (two parallel sets in series) for some serious cranking power. No start.

Here's the kicker that's confusing: I pulled wire 54a to compare smoke and I saw no difference after a full 20 second cranking cycle. I tested to ensure there was power present at both wires with the switch in run position and the engine cold. I'm going to try bleeding fuel at the injectors just to be sure there's not still air, but failing that, does anyone have ideas?

 

[05blackduramax]

Put a clear hose on the injection pump return line and see if you are getting air.

 

[155mm]

A diesel only needs 3 things to run: fuel, compression, and air. So you have verified 2 of the 3, air for the air cleaner check, compression for the extra batteries and it cranks, so only thing left is fuel.

Purged the metal fuel lines at all 8 of the injectors like you said? It makes a mess so get the drysweep out. That is one of the very first things that should be checked.

Have you checked to see if you have return fuel at the IP? also verify the check valve on the IP is still intact. check valve has a small glass ball with a spring behind it, some think it runs better without the check and they break the glass ball. If the vehicle sets for a long time, then the vehicle looses prime.

I am just running at the brain here, those are where I would start. Even after the truck starts, still purge the other injectors, its much easier with the truck stumble running than just cranking the starter.

 

[Dock Rocker]

Have you checked the neutral safety switch? Jump the switch and see what happens.


Sent from my iPhone using Tapatalk

 

[Wire Fox]

Put a clear hose on the injection pump return line and see if you are getting air.

A diesel only needs 3 things to run: fuel, compression, and air. So you have verified 2 of the 3, air for the air cleaner check, compression for the extra batteries and it cranks, so only thing left is fuel.

Purged the metal fuel lines at all 8 of the injectors like you said? It makes a mess so get the drysweep out. That is one of the very first things that should be checked.

Have you checked to see if you have return fuel at the IP? also verify the check valve on the IP is still intact. check valve has a small glass ball with a spring behind it, some think it runs better without the check and they break the glass ball. If the vehicle sets for a long time, then the vehicle looses prime.

I am just running at the brain here, those are where I would start. Even after the truck starts, still purge the other injectors, its much easier with the truck stumble running than just cranking the starter.

Excellent advice on all of these. I'm not a very experienced diesel mechanic, so these are good things for me to check out that I wouldn't have thought of. I'll try them tonight!

Have you checked the neutral safety switch? Jump the switch and see what happens.

I believe that the neutral safety switch just inhibits cranking. Since my enginge cranks [and doesn't if I put it into gear] I believe that this system is functioning correctly. Thank you for the suggestion, as this is an item often overlooked by new HMMWV mechanics and was a think I overlooked the first time I tried to start my HMMWV when I bought it.

 

[diesel dave]

I would check ALL the glow plugs with a meter. If only 2or3 have failed,your truck won't start or in the very least,be difacult to start. Also,an 8 second cycle time seems short. Cycling too quick will not allow the plugs to warm the chamber for starting.

 

[Wire Fox]

Update: I'm hitting the books for more troubleshooting steps. I put a clear line on the return check valve and fuel flowed perfectly clear with not even fine air bubbles. The fuel completely filled the 1/4" ID hose that was about 24" long in about 10 seconds, if that gives an idea of flow rate. I tried to do an injector bleed from that point by cracking open the connector while the engine cranked...no spray, no anything. I took it up a step further and completely opened it and separated the line from the injector and tried cranking...no flow (and now I'll definitely have to bleed that once I do have fuel flow).

So, my fuel pump is pumping, but my IP isn't delivering fuel to my injectors.

 

[NDT]

See if the injection pump makes clicking sounds when someone turns on the ignition.

 

[Wire Fox]

See if the injection pump makes clicking sounds when someone turns on the ignition.

Just was actually doing that as soon as I wrote my above reply. Even better, the A1 Troubleshooting guide states to leave the ignition in run position, then disconnect wire 54a...then temporarily touch and remove that wire to the connector to see if the solenoid toggles. Mine toggled on and off as expected. Continuing the test, I disconnected the cold advance switch and used a jumper wire from leads 569a and 569b, hearing a faint click of the cold advance solenoid. Lastly, I did a continuity test on the cold advance switch itself, with the engine cold, the switch leads have continuity, showing that it at least should have the cold advance solenoid active while the engine is cold.

That just leaves me with the last step of the fuel injection pump troubleshooting guide: "If you have fuel at the fuel injection pump inlet port and no fuel at the injectors, indication is that the pump has internal malfunctions."

The conclusion is that my injection pump is internally malfunctioning...the real question is...where? More to read...

 

[NDT]

The "where" is a mystery that the pump rebuilder figures out. They tell me there is a large plastic ring inside that splits due to age.

 

[Wire Fox]

The "where" is a mystery that the pump rebuilder figures out. They tell me there is a large plastic ring inside that splits due to age.

I potentially will be that pump rebuilder, but will decide that when I read some more on it. I already have the full rebuild kit (bought it to replace servo advance seal, which it still ran after I replaced that seal...and ran without leaking fuel in the valley any longer) standing by, plus I bought one of the HMMWV service tool sets, so I have all of the holding blocks, seal, and bearing tools to do the job. I also may just buy a 6.5L pump, since it will take the military TPS I have on my shelf (I was going to use a civi unit on my current pump instead) and it'd be nice to have the richer fuel flow at factory spec to unlock the extra bit of potential in my 6.5L "6.2 replacement".

 

[NDT]

Wow, you take insourcing to a whole new level. I take the pump to the shop and say "fix it" and write a check for $500.