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Message: [QUOTE="Strictly Diesel, post: 611890, member: 1411"] Maintaining pressure comes down to 2 issues...flow and regulation. The flow from the pump has to be adequate AT FULL DEMAND/LOAD and the pressure regulator has to be able to properly close to keep the pressure up. It's that simple. Generally speaking, "Stage II" injectors (160cc Singles with 80-100% nozzles) and larger tend to experience pressure drop issues with a single stock pump (pump doesn't flow enough). Of course, the condition of the stock pump being used comes into play here as well...I'm speaking generally based on what we've seen over the years. While the injectors in this case are larger (200cc), the nozzles are relatively small (only 30%). This could very well be why he's only dropping to 50psi (and why "DieselFever" doesn't have any significant drop at all). There is a good chance the changing the fuel pump won't fix or even change the problem in this case (unless the replacement is so ridiculoulsy large that it outflows the return capability and causes artificially elevated pressures). The difference between the OP and DieselFever (using the same pump and injectors)...an upgraded fuel system with proper pressure management. You simply can't ask the stock regulator, with it's tiny spring and poppet, to properly do the job. They are fine for "stock", but when more of the fuel is being used by the injectors, the factory poppet (even with a shimmed or stiffer spring) just can't prevent enough return flow to keep the pressure up. Moving to higher flowing lines and a quality pressure regulator has solved many fuel pressure problems that people wanted to blame on the pump...in both 7.3L and 6.0L trucks. [/QUOTE]