93 bronco 5.8l somtimes truck wont start have noticed when not starting fuel pump running all the time if I turn key on/off and pump cycles truck starts right up checked digram relay is turning on and off with key also have fuel pressure on diagram shows pin 8 is input voltage from pump relay,where is module? and not getting this would pump run all the time and prevent starting

 

Welcome to FTE and the Big Bronco Forum. We will endeavor to get you the most accurate information we can muster. If it takes a little time to get an answer it just means the weather is nice enough that we are all out doing stuff to our own trucks.

Are you saying the pump runs even with the key OFF? If so, you've got a sticky FP relay. I dare say it would surprise me that the pump is still working if it never shuts off. I would be more inclined to believe you are just getting intermittent relay activation. The relay is in the under-hood power distribution box. I don't recall which position it's in but the operator's manual diagrams the distro. fuses and relays pretty well. The nice thing about your 93 is ALL of the relays in the under-hood distro. are the SAME PART. They are completely interchangeable with each other. So if you are concerned that the FP relay is a problem, you can swap say the ABS relay temporarily to see if the FP relay is indeed the issue. If the same problem persists, its unlikely that the relay is the issue and you can put the two relays back where they were or just leave them... they are the same after all.

 

no pump cycles on/off with key. relay not stuck when turning on ignition normaly pump runs a couple of seconds then turns off until motor starts

 

So, it continues to run while the engine cranks but only once in a while? Since the problem is intermittent, I would venture to say that the problem is most likely NOT fuel pump, relay or fuel pressure related. The PCM knows to stop the pump from priming when it gets sufficient PIP sensor frequency. The Profile Ignition Pickup (PIP) sensor is a difficult sensor to test and can function well enough for a long time without triggering any codes. My suggestion before going any further would be to pull codes and see if the PCM can give you any insight as to the issue(s) before tearing into anything else. Run both a KOEO and KOER test. If neither yields anything, then you can worry about having to chase an intermittent PIP sensor problem.

 

Check the CM, Continuous Memory codes too while you are at it.

 

just let everone know bronco finally got to the point where it would not start at all and only giving code 111 ecm was sending signal to f/p relay and 12v coming back on pin 8 but no injector pulse replaced ecm and now working fine

 

Congratulations! It is such a good feeling when you finally find the culprit isn't it?