Help I'm goin crazy here....I have a 1990 FORD F150,4.9 custom 4x4..When i go to turn the key to the on position the check engine light will stay on and the pump will keep running and not turn off..Ok here's the deal....It does it most of the time,but not all the time..when it does do it,i have to spray starting fluid to get it to run and then it bucks,misses,blows black smoke and the check engine light still stays on..On the few times that the check engine light goes out after a second or 2,well it runs great,no miss or nothing..then all the suddin it's back to check engine light comming on and going crazy..
Ok here's the kicker.......when the pump shut off after a second and the check egine light goes off too,i can get codes(everything ok)...but.....when it's acting up and pumps keep running and light stays on,cant read the codes(had three places try and everyone said that on their scanner that it would detect the computer but the cumputer wouldn't let it get into it...
Ok here's everything I've done....new fuel pump,filter,full tune up,fuel relay,eec relay,good grounds all the way around ,power to the relays,new o2 sencer,fuel presure check,pulled each sencor plugin loose at a time and still no differance...... i have looked at about 1000 QandA on here and other forums...i have yet to hear anyone say anything about the check engine light staying on and the fuel pump stay running in the on position and not able to read NO codes when it does that.....

 

This behavior suggests the PCM is bad. The electronics are designed as follows:
When power is applied to the PCM, the PCM is reset and the check-engine light output is forced "on". If the PCM is alive and the tests pass, the PCM will shut the check engine light off. If the PCM is dead, the computer code inside it will not run, and the check-engine light won't shut off. It appears the fuel pump relay is controlled similarly.

A PCM which cannot run its internal program cannot be coaxed into outputting codes.

There is a slight chance the problem is a power or ground problem to the PCM. Check the EEC power relay. Check the chassis and battery grounds.

But the most likely answer, in the words of DeForest Kelley: "He's dead, Jim".

 

Hey fefarms,Thanks i needed someone to tell me that too,before i went and tried a computer..lol and thanks for the "IT'S dead" reply,that made me laugh and after being serious on this,it was a relief...
I went to a "U WRENCH IT" place here in columbus this morning and found a computer ,but it was for an automatic and not standard.I got it anyways just to see if i would get codes and for $13.50 was worth a try...It worked I got CODES ..
Actually everything worked..I pulled the codes and only thing it showed was the codes for automatic tranny..Now.........Since mine is a standard,will it hurt to use this computer,or should i bite the bullet and get the one for it?Again I will prob get the new one for it,but just wander if the one in it will hurt it?
Thanks again for the help