I Have a 1999 F250 with a 7.3 diesel and it is idling rough or at low rpm's.I cant run a hose off the valve on back of the fuel filter when idling and there are air bubbles in fuel.Someone mention to me that the injector pump may have a crack in it.Any ideas on troubleshooting will be appreciated.

 

You dont have a injector pump. Check for fuel mods on here. They will help you.

 

And welcome to FTE. I am still fairly new and all i can say is hope you are ready to learn.

 

Stupid question but is your fuel tank full? You have a frame mounted fuel pump and a sending unit with a pickup. Everything else is metal lines, a crack should reveal itself as a damp line or a full out leak. Inspect the metal lines all the way back to the tank. The other option is the sending unit pick up has come off. You will have to drop the tank to inspect it.

 

If you go into the tank you might consider this mod
http://www.guzzle7pt3.com/hutch.php
http://community.webshots.com/album/32303501JuYKPH
the second link shows just how much air the return line feeds into the tank

 

The valve on the back of the stock fuel bowl is a drain valve, I've never ran my truck with the valve open but seeing air bubbles in a line attached to the drain wouldn't concern me much.

 

If you open the drain valve when the truck is running your going to make a huge mess. Tons of fuel should be pouring out.

 

I wonder how much of the air is from the quick connect fuel lines that are operating under vacuum from the tank to the rail pump? Perhaps just changing out these connectors and this one length of hose may solve your problem. The trick is to identify if air is the problem and where to start.

 

I guess the next ? would be, what types of line is suitable to replace it with? Do you have to go with a fuel injected type such as 30R7 or would something a little cheaper like a trans cooler line or is standard fuel line suitable?

 

Use fuel rated line...

The popular kit is the ITP kit, which is the one I used. Very nice and worth the $$$. Here's a link:
http://www.itpdiesel.com/store.php/products/73L_TankKit

 

Last summers ITP kit had black hose with a blue liner inside the hose. I thought was cool stuff.
Last weeks kit i just got , had Braided black hose with Black liner inside it.. Even cooler stuff. I am jealous my truck don't have this new stuff..