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Originally Posted by larry4888
This is a continuation of my earlier post, 94 Ranger No Fuel. Here is the latest.
I jumped the wire at the PCM and the fuel pump comes on so I figured that it has to be the PCM, however, the truck still won't start with the fuel pump jumped so that it is on. I am getting plenty of fuel pressure at the fuel rails with the pump jumped at the PCM. I also have power at the injectors. Why will the truck run if I dump fuel in the intake, but not when I jump the fuel pump? Could it still be the PCM doing something to the injectors so they won't dump fuel into the cylinders? I can't think of anything else that it could be and I don't want to buy a PCM if I am not sure that it is the problem. Unfortuantely, around my area, if I buy an electrical component I own it.
I am at a loss, any ideas would be greatly appreciated.
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Larry you say that you have power at the injectors. How did you check this? If you just put a meter on and saw some voltage without cranking, then I suspect that's the problem. Check to see if the injectors are being pulsed by the PCM. A noid light would show you this. If it turns out the injectors are not being fired, then it's possible that the PCM has picked up a fault. I'll have to do some research, but it seems that if the crank signal is missing, the PCM won't supply any signals to the injectors. Also, since the truck starts when fuel is poured down the intake, it sounds like the ignition is working okay. Do you have a wiring diagram to see if the PCM side of the fuel pump relay goes through anything else (maybe a connector, etc.). I'll take a look at my manual tonight and see if I can come up with anything else. I'm like you, before I change that PCM, I want to feel pretty sure that it's bad.