Okay so I have a 96 f150, it had an obd2 straight 6 with a mr5 trans. Recently I took on the challenge of putting a 351w obd1 and a zf5 in place with the computer and engine harness. I have spark, I have fuel at the fuel rail. I haven't tested the pressure but it seems good. When I turn the key forward, I should have 12v at the injecters, but instead it's .05v. The relays are good and I have voltage at the relay box. Anybody have any ideas before I go carborated?

 

So you replaced ALL the wiring in the engine bay plus the PCM? Given that you said ZF trans I'm guessing the 5.8 powertrain was from an HD truck?

 

Yes sir. It was 94 f250 5.8 auto engine and 93 f250 manual trans ecu and wiring harness. I would have just used all from the 93 manual but the engine had already had much of it taken apart before I found it. I'm going to get that ford scan tool off amazon for $28 on Tuesday and see if it will pull anything from the eec test connection but until I'm stuck with the digital multimeter.

 

The red wire from the PCM Power Relay powers all the fuel injectors, the fuel pump relay coil and power the PCM Computer.

So if you have no power at the fuel injectors red wire you will not have any fuel at the rail and of course the PCM Computer will not operate and you will not be able to read codes.

 

Well my fuel pump comes on and it's a pumpin fuel to the rails and my coil is working. I got spark at the spark plugs. The second relay from the fender is the relay I'm worried about right? I got power at two of the relay connecters on that particular relay. The red wire at the fuel injectors is what I tested at .05v.

 

The red wire should be hot anytime the PCM Power relay is picked.



/

 

So do you think it's a sensor not telling the pcm to supply power to the injectors? Or does it not work that way? I know that the pcm is supposed to ground them out and that's how they operate but does it also control the power?

 

The PCM controls how long the injectors fire by grounding them at different time periods.

The PCM does not supply power to the injectors. The Ignition switch supplies the power to the coil of the PCM Power Relay to pick the relay through fuse "U". The other side of the coil of the relay is grounded at G100 on the drivers side radiator support. The radiator support is grounded by G101 on the passenger side with a large wire running from that point to the NEG battery post.

When the PCM power relay is picked the red wire will be hot going to the Injectors as long as fuse "I" is OK.

 

I don't know what happened but the reply I had made isn't here. Oh well life goes on. So today I purchased the eec scanner and should be here on Friday. I appreciate the schematics, although I had a hard time looking at it and applying it to what I saw under the hood.

 

I'm going to go check that right now.