No signal from ECM to fuel pump relay

[Channeled 91]

fuel injectors no injecting either.

 

[Mark Gilbert]

Did it run when you got it with the gauges the way they are? I can't remember from your build thread. If my memory is right, the PCM only sends a short 12v+ signal to the fuel pump for priming purposes. Once the fuel system is primed and you start the engine the oil pressure switch/sensor maintains the voltage to the fuel pump. I installed a 91 454 and TBI assembly into an 85 C10 a couple years ago, and I had a similar problem until I realized what it was.

https://www.obd-codes.com/faq/gm-aldl-connector.gif

In that picture Pin G is for the fuel pump and if you provide 12v+ power to it you should get fuel pressure.

If you know what model ECM you have I can get you the pinout diagrams for it so you can trace it back in case you do have a bad PCM. I don't think you do from your description, but it doesn't hurt to check.

There used to be a webpage that had specs for common oil pressure sending units, if you find the right one you can run the switch and the gauge from the same sending unit. It's how I got the 91 engine to run the 85 gauge and the switch with one sensor, because the 91 gauge has a different resistance sweep. I can link a catalog that might help, but it is needs conversions to make it PSI

 

[Channeled 91]

Did it run when you got it with the gauges the way they are? I can't remember from your build thread. If my memory is right, the PCM only sends a short 12v+ signal to the fuel pump for priming purposes. Once the fuel system is primed and you start the engine the oil pressure switch/sensor maintains the voltage to the fuel pump. I installed a 91 454 and TBI assembly into an 85 C10 a couple years ago, and I had a similar problem until I realized what it was.

https://www.obd-codes.com/faq/gm-aldl-connector.gif

In that picture Pin G is for the fuel pump and if you provide 12v+ power to it you should get fuel pressure.

If you know what model ECM you have I can get you the pinout diagrams for it so you can trace it back in case you do have a bad PCM. I don't think you do from your description, but it doesn't hurt to check.

There used to be a webpage that had specs for common oil pressure sending units, if you find the right one you can run the switch and the gauge from the same sending unit. It's how I got the 91 engine to run the 85 gauge and the switch with one sensor, because the 91 gauge has a different resistance sweep. I can link a catalog that might help, but it is needs conversions to make it PSI

ECM

Serv. No. 1227747 ARJT

86ARJT K103330724

16136291 ARJT

Thanks for the help.

 

[Mark Gilbert]

Here is a butt load of information on that pcm

http://www.gearhead-efi.com/Fuel-Injection/showthread.php?304-1227747-ECM-Information-42

I didn't read through all of it, but most things you will need are going to be in there regarding pin out diagrams

You may need to register to get the full benefit, but you won't regret it.

 

[Channeled 91]

do I need some kind of electrical tool for all the stuff

 

[Channeled 91]

Are you sure you don't have the fuel pump oil pressure switch? It's a 2 wire switch (not a sensor) on the back of the engine near the distributor.

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I havent seen it.