Injectors not fireing

[vortecfiero]

I have spark
I have 12 volts at the injectors
Ecm turns on the fuel pump

a test light shows good circuits to the ecm

the only circuits not hooked up are the IC pump
and the oxy sens

when cranking, a test light on an injectior plug shows nothing, no flashes etc

I have tried diff ecms and chips.....

any ideas ?????

thanks

 

[scotts4]

By a slim chance check the tps check to see if it in clear flood mode that would be over 4 volts ?????????? may be module ?

 

[SY2932]

Double check the connections on your ignition module. If they aren't good, it won't generate a reference pulse preventing the injectors from firing. HTH's

 

[myclone]

Ditto on what Mike said.. Id have to go dig up the info to be sure but I believe the ECM actually grounds the injectors to fire them so if you probe the inj harness with a test light referenced to chassis ground you will get 12v which will fool a lot of ppl into thinking something else is wrong.

To verify hook the ground/aligator clip of your test light to +12v and probe the injector harness with the pointy end while a helper cranks the truck. If you get 0v or therebouts the ECM isnt firing the injectors. The reasom for that, besides what Mike said earlier, could be a number of things including a bad ECM, wiring harness problems, etc.