Fuel pressure test results
 

Hey guys sorry if this is talk about again and again but I have the P0300 code i did the usual even changed the whole distributor... I think my problem is in the fuel system because I it lacks acceleration for a couple seconds then catches up with itself. I have a very rough idle, say if im waiting at a stoplight my car will just shake and RPM's will raise and lower very fast then coming off from the stoplight that idle is that bad the SES light will flash when i give it gas. By saying 'the usual' i have done plugs, wires, cap, rotor, and distributor. On my fuel test on the on position my psi was 60 then when the pump turned off it jumped to 50 and just kept going down. While the car was on the psi's were rapidly moving from 52-58psi extremely fast. Anyhelp appreciated thanks

You have a leak. What are you driving?

2002 blazer it has only 43k miles on it. where do you think my leak would be? just the fuel line? thanks for the quick response too.

Could be the fuel pressure regulator or the check valve on the fuel pump assembly back in the tank.

The link below (also in my signature) will help you narrow it down:
96+ Fuel System Diagnosis

You will need to connect the fuel pressure gauge into the line going into the fuel filter at the tank to determine where the leak is occurring.

Ok, i think it could be in my tank because my fuel guage in my car if i put it in nuetral and drive it also fluctuates like if i put it in nuetral it says i have like no gas then it will go up slowly.

thank you swart for you help. i tested it again. ran and bought a new fuel filter ($12.98) and that fixed my problem. greatly appreciated!

Hope the filter works. I had the same problem changed the filter and it worked great for two weeks. Than came back, started running 93 Octane from Ft. drum and it went away for awhile. Ended up changing my fuel pump and sender and it never came back. Just a thought if it attacks again.