How do I check if Injectors are firing?

[87yj]

I'm still fighting a no start problem with my 98 explorer 5.0 engine.

How can I test if the computer is firing the fuel injectors?

I've got fire and fuel pressure already...not sure if the injectors are firing or not?

Please help!

 

[Alec]

The best way is with a logic probe.

The power wire to the injector should have a solid red light on the probe
the ground wire should have alternating green and red lights with flashing yellow too.

A logic probe is $12 @ radioshack.

 

[MrShorty]

Fuel injectors can usually be heard using a stethoscope. Alternatively, you can get a little gadget called a "noid" light that hooks up to an injector and flashes as the computer energizes the injector.

 

[aldive]

I have always had good luck with a stethoscope.

 

[V8BoatBuilder]

FYI. You can only reach 3 of the 8 injectors with the intake manifold in place.

I would try the stethoscope first, Autozone sells them for 10 bucks with a long metal probe on them. Disconnecting the plugs could lead to breaking the plastic tabs on the wiring harness.

Next step would be the logic probe or a NOID light. Some carparts places rent them for free.