If you've narrowed it down to an injector problem, the 100% sure way to check it is to replace it and see if that fixed the stumble. BUT, that can get expensive. Parts stores probably won't take it back once they've sold it to you. You can research some and find the resistence specs. Check the resistence on the suspected injector against the specs. Keep in mind that resistence specs are temperature sensitive, so allow some variation in the Ohms depending on the temperature of the injector. An old school way to check it is use a long, flat blade screwdriver. Put the end of it against the injector while the truck is running and put your ear to the handle. Listen for a strong ticking sound. The injector should be ticking, however it can tick and still not be injecting fuel. Using a simple test light connected to Batt Negative (ground), with the key ON, check for Batt + at the injector with it unplugged. If voltage is present, move the test light lead to the POS battery post. Probe the OTHER wire at the injector (still unplugged) and have a helper spin the motor over. The light should flash if the PCM is pulsing the injector. Once you've done all this and ruled out the ingition system (plug and plug wire), replace that injector.
Wednesday, October 8th, 2008 AT 6:22 PM