I need help. Just got my pcm back from pcmforless, but still won't fire. I checked the ohms in the injectors which are good. The injectors are getting 12v. Its getting spark. Also has 45psi fuel pressure. Pulled the plugs and they are dry??? Using the fuel pump hot wire method. Does the computer need to send out a signal to the fuel pump in order to run? I need help?

 

PCM controls the fuel pump via a relay with the stock setup.

 

you can run the fuel pump all you want, but unless the computer tells the injectors to spray it will just cycle through back into the return line. if there is a security (vats) issue, i know it won't fire the injectors. As long as you have a known good motors, and if you are getting spark, and fuel pressure is good, then there is a reason the injectors won't fire

when it's hot wired, does the car run? I guess that's my slight confusion.

 

That's my problem, with the vats tuned out of it, i figured that just running a wire from the fuel pump to the batt. it would be good enough to start. I have yet to even hear any sort of firing coming from it. I know the engine is good because it ran fine when it was carb. And its also getting spark. I don't know what to do.

 

well if the vats is turned off, it should run the injectors reguardless, and fuel pump should be run off of the computer, there is a signal from the computer that can be run to either a factory or aftermarket relay to go ahead and kick on the fuel pump.

wondering if it would fire the plugs if the optical sensor in the opti was not notifying the computer of a cranking situation.

 

Well the starting purple wire and red wire coming from the c100 just go straight to the starter. Is there suppose to be some relation to the computer with those? I actually have a relay and everything, just was trying to see if it would start before.

 

Did you bypass the starter relay, driver side kick panel?

 

no in theory I think it should, because there is no sensor to read back to the computer that a relay is not being used or that the pump is not running, so as long as it's got fuel pressure, the computer should initiate the injectors.

there is another wire that comes straight out of the pcm that is the fuel pump prime wire, but it's been 4 or 5 years since I made my harness and did my swap, but Id have to get the schematics infront of me to find it, and like i said, it's a simple signal wire that turns the relay "on" so that the 12v the relay is getting is sent to the fuel pump wire, much like it's doing with you connecting the FP wire straight to the battery. in that instance though with the computer controlling it, we would be able to see if the fuel pump is priming when you turn on the key.

 

I did not bypass the starter relay. I didn't think I would need to with it turning over like normal. There is no wire going to the fuel pump prime or fuel enable coming from the computer, again I didn't think i needed them if vats was bypassed. Maybe I do need them? The pink wire from the c100 F4 I have going to my distribution block to Ignition hot. Is that correct? the other wires I left alone which are the starter wires. Again it is getting spark to, I'm just baffled at whats going on??

 

Have you pulled the injectors, and prime the tank to see if one or all have alittle fuel coming out. Maybe they're just really clogged