Had a 303 code and came to find fuel shooting out of cylinder 3. Figured the #3 injector is bad so changed it. Before we put it all back we connected fuel meter fuel lines ect. to test it and with KOEO fuel still sprayed out of #3 poppet until the fuel pump stopped priming. My husband started looking at the wiring harness for the metering block (it was a mess) and found a broken wire. It follows right to where #3 injector is. Would it be reasonable to assume this would cause it to be energized when it shouldn't be?

 

What year is the vehicle? Without that information, I can't give you correct diagnosis procedures or wire colors.

Assuming it is 1996 or newer:
All of the injectors are supplied battery voltage through the ECM1 fuse in the underhood fuse panel, (pink wire) whenever the ignition is in the RUN position. The PCM applies ground to open each injector. Each injector has its own ground wire. If there is a broken wire to an injector, the injector will not open. If the trigger wire from the PCM is shorted to ground, the injector will remain open when the ignition is in the RUN position.

EDIT: It is possible that the poppet is stuck open. Unplug the injector electrical connector, turn the ignition to the run position. If fuel squirts from any poppet valve, the poppet is stuck open, and the assembly needs to be replaced.

 

Sorry, it's a 2000 w/4.3 engine. Well, we changed the injector, it still sprays. Upon further investigation my husband found a pink broken/spliced wire leading to #3. He fixed the wire/ harness but it still no difference.

 

Did you replace just #3 injector?





Or did you replace the entire spider assembly?



The pink wire at injector #3 in the harness connector, (terminal "D") must show battery voltage when the ignition is in the RUN position. The pink with black stripe wire at injector #3 in the harness connector, (terminal "C") comes from the PCM. If the pink with black stripe wire shows less than 5 ohms resistance to ground with the ignition in the RUN position, the injector will open and squirt fuel. If it does not show ground, either the poppet valve or the injector is stuck open.

Here's a very simple way to determine where the problem is: Unplug the injector harness connector from the injector housing. Turn the ignition to the RUN position: if the poppet nozzle squirts fuel, the injector or poppet is stuck open. If it does not squirt fuel, the pink with black stripe wire is shorted to ground.

 

We only changed the one injector. We will try what you suggested as soon as we can. Thanks for the info. Assuming the injector/poppet is good, is it possible for there to be a problem IN the PCM itself (for just one injector to be spraying),I.E. the PCM is bad, or would it have to be somewhere the wiring.

 

Anything is possible, but the chances of the PCM being bad are slim to none Post the results when you can, and if necessary, we can explain how to test for a short to ground in the #3 injector circuit.

 

O.K. Thanks. We'll let you know what happens.

 

CaptainHook quote-
"If the pink with black stripe wire shows less than 5 ohms resistance to ground with the ignition in the RUN position, the injector will open and squirt fuel."


Finally got to working on the truck and tested all the terminals and at #3 terminal "C" we got 0.0 ohms. The rest of them were in the 9.2* range.

So now what would be the best way to track down where its grounding/shorting out?

 

Next step is check to see if the PCM is grounding the pink with black stripe wire inside the PCM. To do this, disconnect the harness connector from the injector housing. Then disconnect the harness connectors at the PCM. At the injector harness connector, check resistance between the pink with black stripe wire, (terminal "C") and battery negative. Post your results.

 

CaptainHook-
Before we saw your last post we unplugged harness at injector and unplugged harness at PCM.

Next tested pink/blk terminal (from inj. harness) to pink/blk terminal (from pcm harness) and got good continuity between the two. Would this indicate that there is no break or grounding out from PCM harness to injector harness? And if so does that point to a PCM problem?