I had already replaced the fuel pump connector and also jumped the fuel pump relay. That all works fine i think. Its just the relay is intermittently working for some reason and i cant figure out why. I have a 1995 ram 2500. I did so much testing but i think i already tested the end of the fuel pump connector and the ground was good. This seems to be all the way back to under the hood, since the relay chooses to not send 12v sometimes. Pin 86 will have 12v, but, sometimes the relay wont double click and then 87 wont send the 12v to the pump

 

PCM *should* trigger ASD/Fuel Pump relays every time you turn the key to on. (keep in mind, if you do it too fast between cycles, the pump won't run.) Might wanna have a look at the PCM connector, make sure everything is clean, and the wires that are supposed to go ground, actually have a good ground.

 

Hmm, i will respectfully have to disagree with that, due to my testing. I have a 5.2L as well, and nomatter how fast i do the ignition on and off repeatedly, that 12v will always be sent out pin 87 of the relay, and you'll hear the fuel pump every single time even at rapid ignition cycles.

To add on to that, even on my truck here with the issue, i actually am not doing it fast. I'll pause for a good second or two. But yeah either way that wouldnt matter as i said above. The issue here is that sometimes that 12v wont get out pin 87 since the relay didnt do its clicking its supposed to do. Thats what im trying to troubleshoot and im not getting anything. I have already done all the relay tests, but, later i will redo it and post the exact results im getting for the pins on the fuel and shutdown relay

 

Im at the point considering a mechanic, but most of them dont do electrical stuff. They would be doing all the same tests ive done, and i'd be paying for that. What would they be doing differently? What kind of tools would they use that would help?

 

Everything is working properly, EXCEPT the relay doesn't seem to be getting its ground on 86. Which points at the PCM. Which you have changed? IIRC..... So, where does the PCM get ITS grounds from?

 

I think I did that last night and the ignition is working properly because pins 86 for fuel pump relay and ASD relay both have 12 volts. Regardless if the relay clicks like it should, or doesn't click, there's still 12 volts properly being sent to pin 86. Which is weird like I said before because if there's 12 volts being sent, why is the relay not clicking. I think you said earlier if I'm getting 12 volts on pin 86 and it's intermittently working, then it pretty much has to be a ground issue you think? Because I already swapped in a used PCM with the exact same serial number off of working vehicle and that changed nothing

 

Okay so i made extension wires for those two relays (so that i have exposed metal for the multimeter) and plugged them back in. Turning key to ignition, pins 30,85,86 will show 12v regardless if the relay clicks or not. When it clicks like its supposed to, pin 87 will show the typical 12v for a brief 1-2seconds to prime the pump. So yeah, nothing irregular is showing there besides obviously when pin 87 doesnt get its 12v due to the relay not working properly. When this happens, the truck of course will never start since the pump isnt receiving voltage.

So now that all that is verified, its a matter of why the 12v is intermittent (why the relay isnt working properly, esp when i tried a different pcm already). If i had a bad ground, id be getting all sorts of codes and the pcm wouldnt even function properly...no?

I'll test some other pins on the connector of the pcm that are relevant to the ground, but im not sure what to do at this point. It seems so simple due to narrowing it down to a specifc spot..

 

11, 12, 34 are all PCM grounds. They all go to the ground right below the power steering pump. I think that's a nut on a stud, with a couple fat wires going to it. Take that apart, clean it good, put it back together. See if that helps.

 

11 and 12 show it's ground (good ground, tested continuity). 34 looks like it's ac relay though? Are you sure you meant 34. But yes I'll also check that stud

According to the engine control schematic, all of these sensors are irrelevant in the ignition phase, correct? I could theoretically disconnect camshaft, crankshaft, whatever, and I will still be getting 12 volts sent out pin 87 as long as the relays and fuses are obviously installed, and PCM is working. Correct? I'm just asking because there has to be a reason why the relay is intermittently working. I would have thought that it's the PCM and that's it..but idk..

 

Yeah, 34 doesn't have anything to do with it, probably.... Did you check where 11 and 12 actually go to ground? Thats about the only thing I can think of that would cause what you are seeing.... as everything else seems to be doing what it is supposed to.