ok I posted on here about the updated spider injection system gm has come out converting from cpi or csfi to mpfi, well here is the thing my 01 one blazer started the hard start symptoms, well I checked fuel pressure...along with the result I visually verified that the fuel pressure regulator was leaking, so I replaced wasn't to long after that it started setting a fuel trim system lean bank two...so I used carburetor spray to check for vacuum leaks...none found, bought a scan tool that provides live data...to check o2 sensors they checked good...well ends up we have sucky intake gaskets anyway so I bought the kit and replaced them with the updated (problem solver) fel pro gaskets...while putting all back together the distributor body cracked so I drove with one screw holding it on for just a couple days, when I started it up after getting it back together it was misfiring.. we double checked plug wires, none were crossed up, it was also setting a misfire for cylinder 2 po302, well I bought a new distributor installed it and the codes (po174 fuel system trim bank 2 too lean) and (po302 misfire cylinder two) are still setting. so I ordered the updated version of the fuel injection spider....I have sinced checked the fuel pressure again it has good pressure with key on (engine off) and also running....when you turn the key off it immediately drops to 0psi...fuel pressure regulator symptoms.....well again another visual verified that not to be....so my question is could the poppet injector in cylinder be leaking fuel (relieving fuel pressure) after the key is that would solve the fuel pressure leak down problem but would that make it "lean" or set a specific misfire code I just spent 200 buck on a brand new updated version of the spider any help or advice before I install it would be greatly appreciated especially if its not the gremlin.

 

It is rather unlikely that both the electronic injector and the poppet nozzle were both leaking causing your pressure loss once the pump shuts off. You can determine this for sure by removing the upper plenum, reinstalling the fuel lines to the spider, and pressurizing the system with all of the poppet nozzles pulled from the bores in the lower intake manifold.

A visual inspection of the regulator only would show a leak to the outside as would occur if the external o-ring were to fail or the bladder inside the regulator were to fail. It would not show you a failure internal to the regulator which could cause pressure to vent into the return line.

If you haven't done so already, the fuel pressure test procedure as detailed in the Tech Article (DIY) section covers a great deal including the use of a shutoff tool to isolate the pump from the rest of the system which will give direction on where the problem actually is. A leaking check valve at the pump will most definitely cause a leak down after the pump shuts off. But you could have a poor internal seal on the FPR as well that is causing low fuel pressure when under demand for fuel. A defect in the pump assembly, specifically the flexible tube running from the pump to the top of the housing, could also cause your symptoms.

And just to clarify the application of the MFI upgrade. It would apply to the SCFI (CSFI) engines only, not the 95 and later CPI engines for which there is no hope for an upgrade such as this.

 

The injector was never leaking the golden looking vacuum controlled regulator dripping fuel out of its nipple with the key off after pressurizing the system I replaced it...no more hard starts...but now its setting a lean code on bank 2 an misfire on cylinder 2 the blazer has almost 200k on it an has a tune up done on it

 

As you have already stated... You still have a problem since the fuel pressure bleeds to zero after the key is off which is what I was commenting to.

Per the thread I mentioned, the fuel pressure must be maintained above 50psi for 10 minutes after the key is turned off (or the pump shuts off on its own).

A lot can be learned from the threads linked to in my signature below and even more from those threads linked to in the tech article index.

 

Well I installed the new upgraded spider assembly last night an it has solved the problem...no more lean codes an no more misfire...it even idles at about 850 900 vs 600 650 before...thanks for the Info I know it may not be a performance mod but it runs like a new truck now