Is the gas cap original? It could be bad. You should still have some pressure after 30 minutes.
I doubt its a fuel pump issue or it would do it all of the time.
Have you checked the throttle body gasket? What about O2 sensors?
I think the vehicles that have duel tanks also have a secondary fuel pump along the frame rail somewhere. There is also a part along the frame that all of the fuel lines go into and out of. My neighbor has an 88 F150 truck with the duel tanks and we took this part apart and cleaned it. It seems like I remember it had some type of diaphram in it.
Usually when a fuel injected vehicle runs badly when cold, it has too do with some of the sensors that control the vehicle when its in its open loop mode. These sensors could be bad enough to make the truck run bad but not set off the Check engine light. I know you said you have replaced most all of the sensors. Did you use OEM parts or aftermarket?
It also could be the computer. I'll try to think of other things to check for.
wayne
[ January 14, 2006, 01:01 AM: Message edited by: wtd ]
I doubt its a fuel pump issue or it would do it all of the time.
Have you checked the throttle body gasket? What about O2 sensors?
I think the vehicles that have duel tanks also have a secondary fuel pump along the frame rail somewhere. There is also a part along the frame that all of the fuel lines go into and out of. My neighbor has an 88 F150 truck with the duel tanks and we took this part apart and cleaned it. It seems like I remember it had some type of diaphram in it.
Usually when a fuel injected vehicle runs badly when cold, it has too do with some of the sensors that control the vehicle when its in its open loop mode. These sensors could be bad enough to make the truck run bad but not set off the Check engine light. I know you said you have replaced most all of the sensors. Did you use OEM parts or aftermarket?
It also could be the computer. I'll try to think of other things to check for.
wayne
[ January 14, 2006, 01:01 AM: Message edited by: wtd ]