94 C1500 won't start

[dji1]

I started the truck and tested for the injector's ground pulse. I do get a dim light on the test light. Was the light supposed to flickering or stay on since the truck was running? I can use my voltmeter and see what the voltage is if that would help.

 

Does this mean the injector has a problem? Is there a way to test an injector on the vehicle? Would measuring the resistance of an injector mean anything useful? 

 

Thanks

[richard wysong]

Check the working 1 and compare the light it should be  12v bright but the pulse may be so fast that it looks like a solid light. If it's not 12v check at the ECM

[dji1]

I can't really check the working one. If I disconnect it the truck won't run. 

 

How do I check the ecm? 

 

 

[richard wysong]

Can't you test it where you spliced in the new injector harnesses? No need to disconnect the injectors. To check at the ECM , using a wiring diagram determine which wire triggers the bad injector and test it at the ECM, you can take a needle and pierce the insulation on the wire if need be

[dji1]

It looks like the injector is bad. I measured the resistance and it is less than .5 ohms. The good one is 15 ohms. 

 

I also found out that you can connect the injectors with either plug. Also, the individual injector connectors themselves are not polarity sensitive. So, I swapped the plugs and the passenger side would still not work. The driver side still worked. So, I can eliminate the ECM and wiring. 

 

I order a TBI gasket set and a new injector. Should be here in a day or 2. I think I may just remove the complete TBI and work on it off the vehicle. 

 

Thanks for all the help. I will let you know how it turns out.

[asilverblazer]

19 minutes ago, dji1 said:

I also found out that you can connect the injectors with either plug. Also, the individual injector connectors themselves are not polarity sensitive. So, I swapped the plugs and the passenger side would still not work. The driver side still worked. So, I can eliminate the ECM and wiring. 

 

Thanks for all the help. I will let you know how it turns out.

This is what I would have suggested, but sounds like you are nearly there getting it sorted.

[dji1]

I hope so. I am surprised that the truck runs fairly decent with just 1 injector.   

[richard wysong]

I would replace both injectors while you have it apart

[dji1]

I was thinking about doing both. After I take the tbi apart I will clean and look things over. I am still undecided on redoing the fuel regulator. Normally I would just replace everything. Now I just want my truck back and running.

[asilverblazer]

On 5/19/2026 at 9:10 PM, dji1 said:

 Normally I would just replace everything.

Too many variables, you'll never know what was actually wrong with it. What you spent money fixing that wasn't broken, you might fix the original problem and create a new one or worse, NOT fix the original problem, create a new and have multiple issues.

 

This is the WORST strategy for fixing a problem. Work carefully and methodically, test each part carefully prior to replacing, like with the injector. You found the culprit, repaired, then, importantly, confirm the repair solved the problem. Adding another new part to the mix doesn't confirm the original problem has been resolved.

Edited May 22 by asilverblazer