ThGeneral1
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Hello all ....need some help guys I have 2002 Silverado 1500 4.3L with 95000 miles on it..it starting running poorly with a loss of power under load I replaced the plugs, wires, air filter, oil figuring it was time for a tune up... didnt help the problem only got worse I replaced the coil nothing..then it really got bad took a month to get down to this level now only going up to speeds of 30mph so I then checked the fuel pressure when you first turn the key it didnt read at all....it would crank and run at around 55psi when the key was turned off it would drop to zero..so it wasnt holding pressure. I replaced the fuel pressure regulator figuring that was the answer..that helped but didnt solve the prob..now when key was turned on pressure went to 65psi but would bleed down to 20psi in about 5 sec..would run at around 50psi and when key turned off would fall to zero in 10-12 sec. I plugged the return line and it held at 65psi and ran fine so what gives? my new regulator bad? isnt if the return is blocked the pressure should go on up to 75psi? oh im getting P0300 reading on my scan tool..multiple misfires..not enough fuel pressure across the board I imagine....what do I check next? what is causing it to lose pressure through the line? thanks for all replies