no fuel ingector pulse

[zillman71]

1991 ranger 2.3. truck stalled in parking lot,towed home,replaced crank sensor,ignition control module,and passanger side coil pack. have good spark on driver side. i guess passanger side doesnt spark till motor starts? found no injector pulse,have great fuel pressure. replace computer and still nothing,what am i missing!!!

 

[RonD]

All the injectors share a common 12volt wire, Red wire, does it have 12volts with key on?
Power comes from EEC relay, when it closes with key on, EEC(computer), spark and fuel injectors get power

Computer Grounds injectors to open them

1991 should be Batch fire, could be Sequential injection if it has a Cam sensor, but most likely Batch fire.
Batch fire means 1/2 the injectors open every other time, on a V6 that is 3 injectors, on an I4 it is 2 injectors.
So on your I4 there are only 2 injector wires coming from computer, a Tan and a White wire, when theses are grounded injector should open.

Computer has several Ground pin, and they are not all shared inside computer, you could simply have a bad external ground for computer so it can't Ground the injectors.
Injectors #1 and #4 open at the same time, and #2 and #3 open at the same time

Good look here at inside of EEC-IV computer and pins: http://www.auto-diagnostics.info/ford_eec_iv

 

[pickupman6]

Same thing happened to me on my 87 2.9 today. Not sure if yours is set up the same but on mine there's a diode in the harness behind the alternator and somehow the wires coming in and out got chewed up and had bare wires showing that were touching each other. A little liquid tape and I was back on the road.

 

[RonD]

Just had another thought...............Unplug the TPS(throttle position sensor).

Computer has a software routine to Clear Flooded Engine.
You turn on the key
Press gas pedal to the floor and hold it down, TPS is now above 4.5volts
This puts computer in Clear Flooded Engine mode, which SHUTS OFF fuel injectors to Clear Flooded Engine.
If you crank engine at this time it shouldn't start, no fuel injectors.

TPS gets 5volts from computer on top wire.
Center wire is the Return voltage TO the computer
Lower wire is the Ground.

center wire should have .6-.9volts when throttle is closed, above 4.5volts when throttle is wide open(foot to the floor)
If the TPS has failed or top and center wires shorted together you would have no fuel injector pulses.