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Close, but no start, stumped

Started by Katfish, October 18, 2022, 06:44:46 AM

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Katfish

5.7 crate motor with Mopar harness

Tried first start and no dice.
I wired it up to use the factory 70 relay and not the new ECU/harness controls. Like diagrams below.

Symptoms: Fuel pump is not turning on, no 12V feed.
I tried putting 12V directly to fuel pump, PDU pump feed disconnected, engine cranks but it's not trying to start.

I left the 2 wires circled disconnected, are these needed?

I'm guessing whatever is keeping the fuel pump from coming on is also why it won't start.

Where to look from here?

anlauto

That new factory harness does everything for you...you don't need the original starter relay at all...

Read this thread and look at reply #24, this works for me https://forum.e-bodies.org/electrical-and-audio/11/help-i-need-help-please/20316/15
I've taught you everything you know....but I haven't taught you everything I know....
Check out my web site ....  Alan Gallant Automotive Restoration

Dmod1974

 Those have to be hooked up, otherwise the ECM has no idea when you are turning it on or cranking. I assume you can't communicate with it either since it should be offline without the ignition feed. Either way, those are 100%, absolutely needed.


Katfish

Wanted to update the results, followed Alan's wiring diagram and she's alive!
I also kept all this wiring inside the car and out of the engine bay.
I agree it's much cleaner that way.

Really appreciate all the help, on to the next issue..................

anlauto

Quote from: Katfish on October 21, 2022, 04:07:51 PM
Wanted to update the results, followed Alan's wiring diagram and she's alive!
I also kept all this wiring inside the car and out of the engine bay.
I agree it's much cleaner that way.

Really appreciate all the help, on to the next issue..................
That's awesome, I'm glad it worked out for you....I'm doing my third right now, but it's a 70 B Body, so the main dash harness is a different design, but I plan to keep it all inside as well, just have to figure out where and when to cut :brainiac: :rofl:
I've taught you everything you know....but I haven't taught you everything I know....
Check out my web site ....  Alan Gallant Automotive Restoration

Chryco Psycho

Glad you got it started !
I always use the 70 start relay ,in the past I have numerous issues with having the computer control the starter so I use the far simpler 70 system .

Katfish

Quote from: Chryco Psycho on October 22, 2022, 11:05:36 AM
Glad you got it started !
I always use the 70 start relay ,in the past I have numerous issues with having the computer control the starter so I use the far simpler 70 system .

That's what I was originally trying to do.
Do you have a diagram of how you hook it up?
Or what was wrong with my diagram?


Chryco Psycho

I just left the factory wiring in place so the ign triggers the realy & shunts power to the soilnoid on the starter , the  computer just needs to see the signal from sensors to work in the ones I have wired up .