Having intermittent issue with no start. The engine cranks over well, but will not start. Other times, starts right up and runs well. Already replaced the fuel pump. Conducted 50/50 test and starts up with starting fluid, then dies, so obviously a fuel problem. Switched out fuel pump relay with known good relay, cleaned ground for fuel pump, PCM, and Inertia switch. Any ideas on what direction to go from here? Appears fuel pump isn't always activated. What could problem be, and, how to diagnose?

 

Welcome to the forum

Good testing

You should be able to hear the fuel pump run for 2 seconds when key is turned on.
So thats not happening with a No Start?


Long shot
Years ago had a 2.3l with similar issue
There is a computer mode called "Clear Flooded Engine"
It allows the driver to SHUT OFF fuel injectors and crank the engine to dry it out, to "Clear Flooded Engine"

It is set by the TPS(throttle position sensor)
TPS gets 5 volts from the computer, it sends back 1 volt closed.4.5 volts Wide Open(WOT)
IF............RPMS are 0 and TPS is 4.5volts(WOT), computer will turn off fuel injectors

So it you turn on the key
Press gas pedal down to the floor and hold it down
Then crank engine it should NOT start, no fuel injector
As soon as you release gas pedal injectors will start

IF.................TPS is shorting out, or its wires, then computer may be going to "Clear Flooded Engine" mode so crank but no start, only seen this ONE TIME

But if you don't HEAR the fuel pump with key on, its not "Clear Flooded Engine", as this doesn't effect fuel pump power
So listen for it and cycle key on and off a few times

 

It appears that when the no start condition occurs, the fuel pump is not activated as I stated.

 

When that occurs can you see if the FP Relay is "Clicking", have someone turn key to start while you have your finger on the Relay

There are TWO relays in the engine bay fuse box that should "click" closed
The EEC(PCM) relay and the Fuel Pump(FP) Relay which is powered by the EEC Relay

FP relay should "click" closed and then "click" open 2 seconds later
The computer does this by Grounding the coil in this relay

If FP relay is not "clicking" when there is a no start, then problem is most likely UNDER the fuse box, corroded wiring, either from the EEC relay or computers ground wire at the relay

If FP relay is "clicking" closed then could also be corroded wires under fuse box, but you can test for this at the Inertia switch, put a 12v test light or volt meter on the wire at inertia switch and ground test light or meter, then cycle key, you should see 12volts for 2 second then it will drop to 5-8volts, thats the Monitor volts from computer, no amps, just volts so can't run fuel pump

If you see the 12v at inertia switch but no sound from fuel pump then the Pink wire from there to the fuel pump is bad some where, may have to run a new wire from inertia switch to top of gas tank

 

Does anybody know how to remove the power distribution box on a 1998 Ranger to access these wires and connectors?

OK, I got the power distribution box apart and inspected all the wires and connectors. No, corrosion or broken wires. Currently charging the battery as it ran down from sitting during this time. I located and cleaned grounds G101 & G103, although they didn't look bad. Any other suggestions as to where to look for intermittent no-start?