The last thing you want to do is blow anything back at your pump. It is just as bad as blowing it forward into the filter/regulator or actually worse as replacing the pump requires the lift and stuff you do not have. Provided it actually clears the lines, all that debris lands back in your pump. Then the same depris will either go back thru the pump when it runs again further damaging things and then thru the lines again.
If you have a clog in the fuel lines (and not the fuel filter) the chances are you have some sort of degradation of the soft hoses anyway. The pumps themselves have a filter assembly on them in the tank to stop any large debris from damaging the pump, they should not be allowing anything large enough to clog a line to get to the pump. If you have enough in your lines to be causing a blockage in the line itself you have a bigger problem going on you need to research.
Sorry I know that is probably not what you want to hear, but the tolerances of the stuff involved today is not like the old muscle cars and diaphram pumps that could pump out large garbage that would allow a line to be clogged and be cleared by using air to blast clear a line.
I ordered a new filter/regulator should be in today. Just getting ducks in a row if that isn't the issue. The pump and filter and lines to filter are all brand new. So I'm slightly annoyed to be begin with. But with rail pressure being 90psi either return is clogged or reg failed.
Ohh you are talking return line.. hrmmm.. Sounds like the old soft lines maybe put junk in the hardlines? What is normal run pressure for these cars? I would expect it to be higher than 40 like old EFI cars, and with the high performance and boost involved I could see 80-90 as possible?
Is there a way to disconnect the soft lines at the chassis side and maybe attach a short piece of hose to it to blow out onto ground/in a bucket rather than into the tank? Air should be fine to blow thru, just a matter of not blowing the crud into the tank or anything else in the car as it will just migrate around again on you.
It was the return line. Taking it back to dealer next wed for them to remove everything again. However, I did learn through reading the crap out of alldata that the regulator is in tank and is controlled by injector pulse width and a few other sensors. Problem found but no idea how the return could be clogged. Hoping the dealer screwed up the install and pinched or kinked it.
Here is what I was trying to convey about the regulator from alldata:
The fuel pressure regulator attaches to the fuel return pipe on the fuel sender assembly. The fuel pressure regulator is a diaphragm-operated relief valve. A software bias compensates the injector on-time because the fuel pressure regulator is not referenced to manifold vacuum. The injector pulse width varies with the signal from the mass air flow/intake air temperature (MAF/IAT) sensor.
The regulator is in the fuel filter and is not controlled by anything in the computer. I'm 100% positive on this and I've seen everything in the system.
Maybe the software bias Houdini mentioned had you a bit turned around. The computer measures manifold pressure and uses that to determine how much the injectors will flow based on the constant 58 psi fuel rail pressure.