2000 7.3L Cold Start Issue

[ak_obrien]

I recently bought a 2000 F-450 with 70,000 miles for my father, We got it cheap cuz it would not start. I changed the Glow plugs and then the relay next. <<< My mistake. The relay was the issue. And the truck ran great... Until the temperature started dropping. Under 30 degrees, I'd have to plug it in and cycle it for awhile, i think pushing on the accelerator a little would get it goin. It is now below zero and even plugged in it will not start. It cranks over like a maniac but will not fire. As this is my first Powerstroke and first diesel I am very lost. A friend suggested it may be the fuel heater or possible a inertia switch? Any help would be greatly appreciated. Thank You.

[stage3-7.3]

Are you using a winter blend fuel or an additive?

Is your wait to start light on and cycling properly?

I'm starting with the easy stuff first, don't take offense. Some times you can get frustrated when you've had a related problem and ignore the more obvious things.

[ak_obrien]

No blends or additives just ulsd. What is the recommended additive? And yes the wait to start light and everything seems to be working properly.

[greasyF250]

Check fuel pressure, any codes?

[jesilvas]

Winter Operation, Hard Starting, Hissing Sound Etc...
Troubleshooting GPR & GP's

[C.Gift]

Originally Posted by ak_obrien

No blends or additives just ulsd. What is the recommended additive? And yes the wait to start light and everything seems to be working properly.

I'd recommend Power Services Diesel Fuel Supplement. I run it year round and it's always gotten the job done. Course I live in Arizona, so the coldest my trucks have had to deal with is -10F. I'll leave the cranking issue to someone who has more cold weather experience than me. Sorry I can't be more help

[ak_obrien]

No codes shown. how does one go about checking fuel pressure?

[jesilvas]

Not the fuel heater. It tends to short, blow it's fuse which also has the PCM on it, so no power to the PCM will cause a crank but it will not start.
Inertia switch?
When was the last oil change? And what weight oil?

[ak_obrien]

The inertia switch was mentioned by a buddy, he said it can shut off the fuel and is located by the passenger kick panel. other than that I HAVE no idea. The oil was changed just 300 miles ago with i believe Rotella 30w. Did you say it could not be the fuel heater?

[jesilvas]

Oh yea. If you're in a wreck it can trip and shut off the fuel pump.
Oil should be fine for cold starts. Personally, I'd have done 10W-40. Or maybe 5W-40.
If the fuel bowl heater had shorted out, then it would've blown a#30, 30A Maxi fuse which also has the PCM Relay Coil, Ignition Coil (Gasoline only), Fuel Heater (Diesel only), Wastegate Solenoid (Diesel only), Injector Driver Module Relay Coil (Diesel only). If it blew that fuse, you wouldn't see your WTS light when you turn the key on, and the truck would crank but never ever start.
For checking codes, what are you using? These aren't OBDII systems, but CAN I think. Gotta have a good good scan tool.
To make sure the fuel pump is working, you can drain the fuel bowl and pull out your filter, and then with the filter still out, you can turn the key on engine off and the fuel bowl should start filling up.
I still think you have a GP/GPR starting issue. You say you changed the GPs and GPR. What brand? Do you know if the relay is working even though it's new?
Read those links I posted earlier. They'll help I think.