1992  loyal  spfi  ,   key on not cranking .  the fuel pump intermittently will not  run   .  I just replace  the pump  with a known good one .  but it is used .  could it be the pickup coil is dirty ?  what else could it be ?

On the spfi cars the fuel pump will not crank unless the engine is turning. If you put it in self check mode the pump will cycle/pulse key on engine off.

Flakey pump operation could be a bad relay or harness issue. Check the pump ground. I had an ecm once that would not trigger the pump. The driver circuit inside the ecm had failed I suppose.

by not cranking - do you mean the engine isn't turning over at all or it's turning but not starting?

 

are you positive the fuel pump can push enough fuel?  I've had problems with used EA/ER pumps that were good but have sat for long periods of time.

key on engine off  it cycles the pump for a second ,  it doesn't always do that . when I don't hear the pump cycle, that's when it wont  run

So the loyale ecm has a priming pulse? None of the black SPFI ecms Ive used had a priming pulse. Or I dont remember

Neither of the Black ECM's I've swapped into my '88 primes the pump if I just turn the key to "On".

 

Thought it might be the start of an issue, but maybe not going by the above post.