Problem started yesterday, kept trying and it eventually started, ran very rough for 30 sec with lots of black smoke and then started / ran OK for the rest of the day. Today it is worse and will not run for more than 1 sec. Replaced both fuel filters, plenty of fuel in the filter canisters. I am assuming that this is a cold start only problem. Need help on what to do next.

Here are several links that may help:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-8.html#post1415281

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-10.html#post1977241

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-10.html#post1921427

On PSDs, it's important to change the oil and filter every 5,000 miles and to keep the oil level up to the FULL line. Also, be sure to change the air filter every 5,000 miles.

Thanks for the quick response. I had already printed the basic diesel engine troubleshooting post and plan on going through the steps this afternoon. I am leaning on this being a cold start problem. Are there any other sensors to check?

Not really. Most of these situations are resolved through standard diesel engine preventive maintenance. I'll be surprised if it is anything besides engine oil & filter, air, or fuel injectors. Be sure to open up the air box and ensure it hasn't sucked in anything (e.g. rags and paper towels) from the work site or highway.

Update: oil is full, air filter was replaced a couple of months ago, no restrictions. No codes in the computer. When I turn the key, glow plug dash light stays on 5 to 10 sec as normal and I hear a click from the CPCM. I verified B+ voltage at both connectors and 12v on red wire when the key is on. I then disconnected the 2 connectors on each side that go to the glow plugs and using a dvm with one lead connected to the block, ohm'd out the glow plugs and all are less than 1 ohm. I then set my dvm to read dc voltage and with the key off, I read 10.29v on all 8 leads that come from the GPCM. With the key on, still reading 10.29v. This does not make sense. I would think that I should read 0v with the key off and 12v with the key on (for the first 2 min). Any suggestions?

Does the Glow Plug Relay click, when the ignition switch is turned to ON? If not, check wiring and connections before replacing.

Check the ignition switch for wear, pitting, or melting.

I hear a click from the GPCM

No other ideas come to mind. Maybe someone else will chime in.

Be sure to test all under dash and under hood fuses with a test light or multimeter:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-3.html#post252145