2002 7.3 Won't Start

[TrucklessFriend]

I have a 2002 7.3 auto that won't start unless the ignition has been on for at least an hour. When the ignition is cycled, the glow plug light comes on, the fuel pump runs for about 30 secs, and it will crank, but will not start. When the fuel pump is running, it sounds like you can hear an air leak coming from the engine bay. After having the ignition on for an hour, it starts really rough with white/ dark grey smoke out of the tail pipe for about 3 min. Driving it down the road, it does not smoke. Then.... when you get into 4th gear at 40 to 50 mph, the truck bogs down and shudders and shakes and you have to foot it to get it to downshift and accelerate. When you get above 50 mph, the shuddering and shaking goes away as long as you stay above 50mph.

We have replaced the fuel lines, the fuel pump, the high pressure oil lines, the fuel filter, looked at the glow plugs, and are stumped on what is going on. Have talked to multiple diesel techs, dealers, and no one has a clue what is going on. Please help!!!

[TrucklessFriend]

Bump......

[Turbostang500]

Did you check the glow plug relay (gpr) to verify the gp's are getting power?

[TheFordman87]

Idk to much about the 7.3 but I do know they are bad about having fuel leaks usually around the fuel filter if I'm not mistaken. I believe it's the where the filter screws onto. If you have someone cycle the key get as close as you can to it and see if you hear air around it. I would check on that as well. But here is a theory test of mine you could try. If the glow plugs aren't getting power try spraying a little starter fluid and see if it fires up easy.

Once you run the truck for a while all warmed up to normal operating temp if you turn it off will it start back up without having to leave the key on for an hour?

[TrucklessFriend]

Thanks for the replies. I will look at the fuel filter because there is defiantly a hiss in the engine bay.