Powerstroke Diesel Troubles.

[Gearstix]

My uncle has a 2000 7.3L PSD in a welding rig.
If you don't use it for a while, and go to start, it won't go or is hard to start. I think theres a new air filter/fuel filter on it and its got 211,xxx km's on it.
Any other information I'll try to provide..

[DmaxMaverick]

It could be a number of things. More info/details will help.

How long is long?
What do you mean by "not start"? Cranks but not fire? Or not crank? Slow cranking? Clicking?
Does it try to start, but stumble?
Start, then stall?
If it cranks, what comes out the tail pipe while it's not starting? White smoke?

If you aren't sure of the fuel filter, change it. Then you'll be sure. Check the battery voltage (with a VOM) before you try to start it, when it would normally not start, or be hard to start.

As bad as the late model GM trucks are, the Fords are worse when it comes to parasitic battery drain. If it's sitting for a week or two, it would not be surprising if it doesn't start. Oil condition is another factor. If it's in need of a service, it can prevent the injectors from developing enough fuel pressure (via HP oil rail pressure) to pop off.

They also have issues with the cam position sensor. When they fail, or are failing, they can cause several problems, including poor starts.

[SoTxPollock]

It's probably the oil condition, perhaps diluted where it can't fire the injectors. One thing every 7.3 owner will tell you is that you better be very religious about changing the oil and filter on time.

[rustyk]

Although my IH diesel is much older, it's the same base engine; I had a similar problem, which turned out to be the fuel return lines. Also don't discount the possibility that the glow plug timer is sticking.