Correct. I can hear it prime when the relay double clicks, and truck will start in those instances. On an unrelated (?) note, the new installed pump is very odd too. It has moments when its hot out during the day, where i run my tests and it literally wont turn on even being directly jumped from the battery lol. But when it cools down later, its back to working again when jumped directly. So looks like this pump maybe needs swapped anyway...smh. But yes the other new pump that is much more expensive, i have tested and it runs fine. So i'll have to stick that into the gas tank at some point. But anyway thats an easy fix and its unrelated to the main issue. PCM comes tomorrow so if that doesn't solve the intermittent relay issue, then i'll troubleshoot the wires from the PCM to the relay box, and the connections underneath the relay box itself.

 

What brand pump did you install?

 

Okay so the new PCM didnt change anything. Its still an intermittent issue with the relays sending or not sending 12v to the fuel pump. Sometimes it works, sometimes it doesnt. So the PCM made no change. The relays open and close when its working normally, and you can hear the fuel pump running (the brand new one that i have connected just hanging from the truck). But as i said the pump isnt the problem here; its the 12v not being sent to the pump sometimes. I have no idea what to troubleshoot at this point if the PCM didnt solve the weird issue...

 

Verify you are getting power to pin 85 when the pump doesn't want to run. (yeah, that's gonna be fun.)

 

Pin 85 on relay? Yeah i have checked pin 51 (shutdown relay) in PCM while also other pin 87 (i think) on auto shutdown relay for continuity, and it appeared normal. I'll check when its hot out and wiggle wires around to check. Is this what you meant to do? If so, i think i already verified that, esp when i jumped it and im getting sparks and also good readings on the multimeter. But yes can you verify what you meant

I will also disconnect the connectors in the front of the door on the bottom of frame, as this removes the entire mid/rear electrical from the equation (which i already know isnt the issue, but it helps to narrow things down even more)

 

On the relay, pin 30 is constant power, pin 85 is power with ignition on, 86 goes to the PCM, for the control circuit, 87 is power feed OUT to whatever.

 

Checked ASD and fuel pump relay. Pin 86 has 12v going to it, when the key is turned to ignition. Regardless if there is the normal double relay click, or no click, pin 86 gets 12v. It just makes no sense bc when it doesnt click, pin 87 obviously wont send that 12v to the fuel pump. Already stuck on another PCM, so what is telling the relay to not click? Something has to be? It should always double click. I dont get it..

I was suggested fuse box is bad, but i mean besides being dusty, it looks brand new all things considered. Same with the wires. Even so, that wouldnt explain why this is intermittent and why the relay decides to not click sometimes (which means pin 87 has no voltage in those cases).

 

If you are getting 12 volts where it is supposed to be, then the problem has to be in the ground side of the equation. So, verify the PCM is getting power where it needs it, and has a good ground.

Do you have a good scanner??

 

Can you explain why you think its the ground side of the equation so that i can understand better?

As for the PCM, well, i did tests but idk. So, ASD and fuel pump pin 85? (or 86..idr) share the same wiring in terms of going to the pcm (pin 51 on the pcm). Checked the ground (put a probe into the PCM pin 51, and other side of multimeter to the relay pin 86 or 85) and it shows 0 as it should when doing the continuity test. Im not sure what kind of tests to run for the ground, so any input would be helpful for both relays

I do have a good scanner but only for my other dodge which is OBD2, this one is OBD1 unfortunately. I have no relevant codes showing on the blinking CEL either btw, so thats no help either. Scanner for what, btw? How can i verify the PCM is getting power where it needs it, and has a good ground. Doesnt my above test show its ground is fine?

 

On my truck. My fuel pump quit working altogether. had it replaced. Lasted two days...... had it replaced again, wouldn't start when I went to pick it up...... Turns out, the fuel pump ground was bad. Took it apart, cleaned it, and no problem since.

What year is your truck?