I know it runs while under high consumption....I'm talking about when you turn your key on. It should prime then shut off, mine isn't shutting off. I replaced the relay under the hood. Fuel pump next? When I do get it started, it runs rough and blows black smoke (smells rich too) After a bet, 10 minutes or so, CEL will go away, it will kind of back fire, and run like a champ.

It's a "93 4x4...

CEL does come on, but I have never been able to get a code reader to work on this truck...don't know why...

 

Get this...With the CEL on the fuel pressure is sitting around 38psi. After a while at idle the CEL kicked off and it went to running smooth. Fuel pressure dropped to 32psi, where it should be...Turned the key off then back on, fuel pump primed and shut off. Fuel pressure regulator? That's my guess....