Major misfire problems.

[crzy8mnky]

The injectors are the stock flex fuel injectors, which run 33lbs at 48 PSI. I'm using the stock tune, so I don't think this is the issue.

So I replaced the regulator and it still showed 40 PSI. Sometimes it will go up to 50 though, and when I pinch the return line I can control the pressure. However, none of this has made a difference in curing the misfires. I pulled the injectors and send them to be ultrasonically cleaned, since I don't know their history. If this doesn't fix the issue then I'm out of ideas.

[George C]

if you are at 40psi and tune is stock then the scaling is off

you either need to scale injectors for 40psi or figure out how to raise pressure

[crzy8mnky]

I was able to raise the pressure by crimping the return fuel line and it made no difference.

[George C]

I was able to raise the pressure by crimping the return fuel line and it made no difference.

crimping the line now restricts volume....motors need to see a certain psi and a certain volume

[crzy8mnky]

It was the return line, not feed. Regardless, it did not seem to make a difference as the truck ran poorly no matter what the pressure was at.

[George C]

restricting any line will cause issues but either way any time i seen your issues it was purely a fuel delivery issue

[crzy8mnky]

That's what I'm thinking, especially since both O2 sensors are showing lean. Hopefully getting the injectors cleaned will take care of it The weird thing with the rail pressure is that immediately when I turn the key it will jump to 50, and then the pump will shut off and it will drop to 40. And when it's running it will go anywhere from 37 to 50. The first regulator was a brand new AC Delco part and this new one is a BWD and the same thing occurs.