4.8l silverado misfire.

[mbtransam]

My dad has a 99 silverado with the 4.8L. In the last two weeks it has developed a rough idle and is very difficult to start (starter is strong, just takes a long time to start). MIL was on and I scanned it, found po300 generic misfire code. I am leaning towards a problem with the fuel system, but im not on the up and up with problems on these trucks. Any one got any suggestions (injectors, pressure regulator, or something that im not even thinking of), thanks in advance for any help.

[ChevyTech007]

Need to know which cyls are missing. If it is 5 & or 7, there is a good chance that the injectors are clogged. The fuel comes in at the center of the left injector rail and the rear is lower than the front so any sediment goes to 5 and 7. I have seen the inside of the supply line rust and come apart filling the injector inlet screens with debris. Best way to tell is to pull the fuel rail and the injectors, then tap them upside down on a paper towel.

[Gary_602Z]

Need to know which cyls are missing. If it is 5 & or 7, there is a good chance that the injectors are clogged. The fuel comes in at the center of the left injector rail and the rear is lower than the front so any sediment goes to 5 and 7. I have seen the inside of the supply line rust and come apart filling the injector inlet screens with debris. Best way to tell is to pull the fuel rail and the injectors, then tap them upside down on a paper towel.

 

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Check for a TSB on the Evap line. I pulled 24 oz. of water out of my charcoal canister because of it.

 

Gary

[mbtransam]

The fuel pressure regulator had ruptured, replaced it this morning. Thanks for the help.