My 86 S10 Blazer 2.8L V6 will crank but not start. When I turn the key to the run position i don't hear the fuel pump prime. I put a new fuel pump relay in today and the problem is still present. I have tried putting +12V to the FPR bypass and the pump starts just like normal and the truck starts right up.

Also I just found out my headlights are no longer working. Could this all be caused by a bad ECM?

I'm very new to DIY car repair so any advice would be appreciated.

 

Did you check the FPR & headlight fuses? Never overlook the obvious. If they are good then check to see if the FPR is getting 12 volts when the key is turned on. If it does then change the FPR.

 

Yup, X2. If you put 12 volts on the relay wire that goes to the pump, it works, and you are getting voltage to the relay coil, bad relay. I don't know about your truck, my lumina has the fpr, and cooling fan relay next to each other. I thought I had a bad pump, but was able to interchange those two relays to check the circuit.

 

Thanks oldchevy and kevinkpk!
Turns out it was a bad connection on my ECMB fuse.
I appreciate the help!