Dreaded P0192 code. Fuel issue

MS6 P.C.

MS6 P.C.

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So after installing a new (built) motor, can't seem to get this P0192 code figured out. Fuel rail pressure sensor circuit low input. From what I read, it means fuel pressure isn't hitting the desired target. I do have port injection that is T'd at the hpfp, but I am gettin fuel from the hose coming off the firewall.

Replaced fprv with parts car and worked for 2 drive cycles (approx 8 miles). Then bought new one from Mazda, no luck. Swapped spill valve off parts car, no luck. Swapped pressure sensor off parts car, no luck. Pulled hpfp with Autotech's and installed stock hpfp with no luck.

I think it has to be a wiring issue because sometimes it will read, and then will not. I will attach some logs for those who want to look. I find it odd though that sometimes the afr will be pegged at 14.85 when the car is running (log 308). One of the logs show the car running with no pressure (log 309). I'm not good at diagnosing electrical issues, that's why I came here for help. I checked the wires going to the sensor (I should note I have Eric's wire tuck), checked the wires at the fuse box under the hood and can't find anything that looks damaged. Unplugged and plugged stuff back in. Tried cleaning connectors and pins on that sensor and the plug by the fuse box. I have a multimeter but have never used it and not sure how to check the voltages properly.
Logs 315 and 316 are what it does now, which is not run, and if it starts, it quickly dies.
 

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MS6 P.C. said:
So after installing a new (built) motor, can't seem to get this P0192 code figured out. Fuel rail pressure sensor circuit low input. From what I read, it means fuel pressure isn't hitting the desired target. I do have port injection that is T'd at the hpfp, but I am gettin fuel from the hose coming off the firewall.

Replaced fprv with parts car and worked for 2 drive cycles (approx 8 miles). Then bought new one from Mazda, no luck. Swapped spill valve off parts car, no luck. Swapped pressure sensor off parts car, no luck. Pulled hpfp with Autotech's and installed stock hpfp with no luck.

I think it has to be a wiring issue because sometimes it will read, and then will not. I will attach some logs for those who want to look. I find it odd though that sometimes the afr will be pegged at 14.85 when the car is running (log 308). One of the logs show the car running with no pressure (log 309). I'm not good at diagnosing electrical issues, that's why I came here for help. I checked the wires going to the sensor (I should note I have Eric's wire tuck), checked the wires at the fuse box under the hood and can't find anything that looks damaged. Unplugged and plugged stuff back in. Tried cleaning connectors and pins on that sensor and the plug by the fuse box. I have a multimeter but have never used it and not sure how to check the voltages properly.
Logs 315 and 316 are what it does now, which is not run, and if it starts, it quickly dies.
Click to expand...

Double check you fuel rail pressure sensor plug, it might not have snapped in all the way "I have had that issue". When the car starts I don't see any pressure being registered. Double check your ground wires too. Try having a friend wiggle the harness while you start the car to see if that changes anything.

https://www.revisionsrus.com/logs/2177

upload_2021-10-12_16-50-44.png
 
Thanks. I'm sure it's in there good as I unplugged it and plugged it in a few times. Plug and sensor look good to the eye, or my eye at least.

It's to the point where the car shows no fuel pressure, where as before, it seemed like it would come and go, like in log 309, making me believe I have a loose connection somewhere.

I remember putting the ground back on at the hpfp, the starter, the passenger motor mount, and power steering pump. Talking to a friend, first thing he suggested was a ground. Then he came to the conclusion it was my prv, which I then replaced

I should note that when I first started the car I was getting a few codes
Maf high circuit
Iat high circuit
Fuel rail low circuit
No communication with ABS module
Instrument cluster not receiving ortransmiting on can bus

First two were remedied by replacing maf from parts car. After checking into wiring and the connections the last two never came back. Just keep having the fuel rail low circuit stay and the car no longer runs.

Thanks for the advice, I'll continue to dig...
Does anyone know if the abs module, fp sensor or o2 use any of the same grounds?
 
An update for today
swapped back the hpfp pump with the autotech internals, checked out the rail and the hardline going to the rail, didn't seeme clogged as there was plenty of fuel in the rail when I removed the hardline.

After trying to start it started and ran for a few seconds, but then died. Also am getting a p0091 code randomly. Fuel pressure regulator 1 control circuit low. As others had noticed with fuel pressure issues, my hpfp voltage stays at 0.

Here are logs taken from today, one where it runs for a few seconds, one where it doesnt start at all.

A very knowledgeable mazda guy I know, believes it is something mechanical. He thinks my in tank pump isn't enough to keep up the flow, but it's a new aem 340lph pump. I swapped out baskets, one with a stock pump in there with no change. With this new code popping up, I wonder if it's not getting enough voltage for the fuel demand after it's running. Time to keep digging though. Any thoughts anyone?
 

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If you have checked a lot of actual mechanical parts check your electrical connectors and harness for the affected system. Especially at the ECU
 
I'll look into that.
Like I mentioned before, I'm not electrically inclined as far as diagnosing those kind of problems. I do know that when I pulled the motor I also pulled the harness from the fuse box under the hood, the one with the crank, alternator, starter wires. It was easier for me that way.
 

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Just an update, changed pressure sensor again with the injector harness and that seemed to take care of my issue. Drove it for about 10/12 miles today, more than I have driven in 3 years. Will update in a few weeks or so to see if everything is fixed.

Prior to this I tried swapping coil pack harness which the car wouldn't stay running.

I had also ran 12v straight to the in tank pump which still wouldn't keep the car running.
 
Had this issue for weeks cane down to a main relay,even after i inspect it and all check out for some reason its sticking have someone press the relay like we did and crank it,i replace tht relay and same issue dealearships send me a wrong one,, and also i was missing the ground side of main relay sa i bypass tht.and all my codes were gone all tht u have listed on codes is the exact same thing i have,hope you get it running
 
Vhinrye said:
Had this issue for weeks cane down to a main relay,even after i inspect it and all check out for some reason its sticking have someone press the relay like we did and crank it,i replace tht relay and same issue dealearships send me a wrong one,, and also i was missing the ground side of main relay sa i bypass tht.and all my codes were gone all tht u have listed on codes is the exact same thing i have,hope you get it running
Click to expand...

It has been running a couple weeks now, my issue was the injector harness itself. It wasn't connecting with the pressure sensor properly. But thank you
 
I'm very glad to run into this thread. I have a 2007 MS3 (original owner) fully stock and I've just now run into this issue. The weird thing in my case is that at cold temp right after starting (it's upper 30's to 40's F in the morning here), it idles fine. Once it starts warming up, then it cuts out, both at idle or WOT. If I let it warm up further then it seems to run fine. Because the problem is not at either extreme of the temperature, I'm thinking the relay could be the issue, but I'm curious what y'all think.
 
AGGATX said:
I'm very glad to run into this thread. I have a 2007 MS3 (original owner) fully stock and I've just now run into this issue. The weird thing in my case is that at cold temp right after starting (it's upper 30's to 40's F in the morning here), it idles fine. Once it starts warming up, then it cuts out, both at idle or WOT. If I let it warm up further then it seems to run fine. Because the problem is not at either extreme of the temperature, I'm thinking the relay could be the issue, but I'm curious what y'all think.
Click to expand...
It's an easy enough thing to just bypass the fuel relay with a jumper. Try that and see.
 
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