I have a 91 4x4 5.0 EFI. Has been running great, then one morning crank and crank but nothing. Seems to be no spark but really hard to check by myself. I do have quite a bit of pressure at the schader valve on fuel rail. (checked that once when it finally cranked.) What I have realized is that fuel pump never turns off. It turned off once and the truck did crank, check engine light came on,and it ran ratty. Turned it off and same thing again. Crank and crank with nothing and pump running. I do now remember the pump would always run a few seconds then turn off. Seems the way the fuel pump is acting, it is related somehow to my problem, but I also don't seem to have spark during this time either. Any ideas?

 

Could be bad pick up coil or ICM. Also check fuel pump relay. Might be stuck on

 

ICM = TFI ignitor

 

Tried truck today, it fired right up and was running fine.. Then cel came on and idle changed greatly. When you press gas pedal, back fires thru intake and won't rev up. Shut truck off and now won't crank again.
I tried pulling codes, but light just stays on, never flashes the first time. Any tips?