[SOLVED] Possible Fuel Pressure Problem

[Yong No]

So this is a very slow project, but I went out today and replaced the PCM pins for the high pressure fuel pump and the car ran great after this. I also installed new Plastic PCM connector hold down cams. Previously mine were missing. I drove the car today and it ran great for about an hour and then the problem came back, and it was the same problem. However through side of the road troubleshooting, I found another bad spot in the wire harness. This is nearly a break in the high pressure fuel sensor wire way down as it going under the intake manifold. I can barely even touch the spot, but I can squeeze it and the problem will come and go with each press/squeeze. I have the car in the garage now. Cleaning the garage has been such a big project that I have not worked on the car. So tomorrow it is suppose to be raining. So I think I will go out there and turn on some heat and pull the factory inner cooler off and see how much access I can get to the wire harness down there. I will likely just run an whole new three wires from the pressure sensor to the PCM. I will post another update when I have this done.

Thank you for the updates of your ordeal. My son encounters the similar problem, and I did not see anyone who solved the problem or share the fix - until this thread. So far the dealer cleaned the throttle body, MAF sensor, and changed spark plugs. And before he went to the dealer I replaced the fuel pump. So far, the car, 2015 Mazda 3, is in same condition, running limp mode. The dealer said the fuel pressure is good, but still the error code P0192 and P0171. You'd think the dealer can fix easily. Really frustrated here. Anyway, thank you for the posting.

 

[DustinDriver]

Thank you for the updates of your ordeal. My son encounters the similar problem, and I did not see anyone who solved the problem or share the fix - until this thread. So far the dealer cleaned the throttle body, MAF sensor, and changed spark plugs. And before he went to the dealer I replaced the fuel pump. So far, the car, 2015 Mazda 3, is in same condition, running limp mode. The dealer said the fuel pressure is good, but still the error code P0192 and P0171. You'd think the dealer can fix easily. Really frustrated here. Anyway, thank you for the posting.

Has anyone figured it out? I'm new and having a similar problem. Any help would be appreciated. I started getting some stumbling then cel light and the fuel rail sensor low voltage code. I replaced sensor. Now the fuel pressure leans out to like 304 at wot and a high of only 1710. Before all of this it was 1870 at wot

 

[Awafrican]

Has anyone figured it out? I'm new and having a similar problem. Any help would be appreciated. I started getting some stumbling then cel light and the fuel rail sensor low voltage code. I replaced sensor. Now the fuel pressure leans out to like 304 at wot and a high of only 1710. Before all of this it was 1870 at wot

Unfortunately OP hasn't been around to give us any updates after finding the PCM to be faulty. I suggest making your own thread in this section, detailing your issue and things you've done to troubleshoot.

Common issues with fuel pressure are; hpfp ground is poor, PRV failure, sticky spill valve.

 

[DustinDriver]

Unfortunately OP hasn't been around to give us any updates after finding the PCM to be faulty. I suggest making your own thread in this section, detailing your issue and things you've done to troubleshoot.

Common issues with fuel pressure are; hpfp ground is poor, PRV failure, sticky spill valve.

I'm only using my phone to communicate on here and am very new. I can't figure out how to create a thread lol took me like 3 days to find a way to type here.

 

[Awafrican]

I'm only using my phone to communicate on here and am very new. I can't figure out how to create a thread lol took me like 3 days to find a way to type here.

Use this link for the troubleshooting new thread
https://mazdaspeeds.org/index.php?forums/mazdaspeed-3-troubleshooting.106/create-thread

If you navigate to the section where you want to post a thread and there's a button top right


I use my phone over 90% of the time, here's a template that helps us know what's going on with your car
https://mazdaspeeds.org/index.php?threads/troubleshooting-sheet.13117/

 

[Joseph Conley]

The final solution was I replace the wire from the PCM to the Fuel pressure sensor and the problem never came back. I beleive ultimately there were several problems along this same wire. I think the PCM connectors was a bigger problem and I when I fixed that in an earlier post it certainly made it much better, but I think there were bad spots further down the wire. Once I replace the entire wire from the PCM to the fuel pressure sensor it completely corrected the problem.