I have a 1991 F150 that has a hard time starting when it is cold in the mornings. I cycle the ignition until the fuel pump finally kicks in after 15 to 20 min. I have changed the tank selector switch made sure the fuel pump relay is working, but can't figure out why when it is cold it won't start.

 

I moved your thread to a forum where you should get more responses.

 

What kind of fuel pressure are you seeing at the rails?

 

Are you saying the FP relay doesn't turn on for the first 15 minutes of key cycles? Or that, even when powered, the FP doesn't spin/create pressure in that time? Have you ever looked inside the EEC, or smelled it (near the e-brake pedal)?

http://www.supermotors.net/registry/media/901696

This photo album explains how the fuel system works:

http://www.supermotors.net/registry/2742/12737-4]How exactly? Click this & read the caption:

http://www.supermotors.net/registry/media/507187