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GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 29523
Experience:  GM Grand Master Technician 2007. 14 years experience.
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2000 silverado 2500: 6.0l..My fuel pump went..fuel filter..p0304 code

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I have a 2000 silverado 2500, with the 6.0l vortec. My fuel pump went out so I replaced it along with the fuel filter about a month ago. A few days after I got a P0304 code, I researched and cleared the code. I changed the plugs and it came right back. Then I switched my coil pack and wire from cylinder4 with the coil pack and wire on cylinder 6 hoping that I would get a P0306 code. The 304 code came back. I then switched the injector from cylinder 2 and 4. Then I got a P0307 code. I checked the wiring and fuel lines to see if something looked odd. Everything looked ok so I cleared the code. Now I get a P0300 code. I fought the 304 code for about two weeks messed with the bank 2 injectors and now I get misfires from both banks.
Welcome Adam. It is not uncommon for debris in the fuel lines to get caught in the inlet of the injector. #7 injector is usually the worst. Another common issue is for the intake gaskets to leak vacuum. I usually spray carb cleaner along the mating surface of the intake manifold to head.
Customer: replied 8 years ago.
I have gone the carb cleaner route and ran two bottles of injector cleaner threw my tank. I understand cylinders 1,2,7 &8 are at the end of the fuel rails I am just confused as to why I only got a P0304 until I swapped injectors out
Did you remove the injectors from the fuel rail?
Customer: replied 8 years ago.
Injectors for cylinders 2 and 4 were removed and swapped with each other
Was there anything in the back of the injector? #7 is usually the worst as it is the closest to the inlet side of the rail. Also, have you tested the fuel pressure? Did you remove the vacuum line from the regulator?
Customer: replied 8 years ago.
I did not remove the fuel rail that houses the #7 injector, maybe tomorrow! I have not checked the F/P yet. I figured that bad pressure would cause a P0300 not a code for only one cylinder. The F/P regulator, I did disconect the vac line and it seemed to have good suction on the hose but I felt nothing on the regulator itself.
You won't get vacuum from the regulator, nor should you have fuel. I would first look at the back of the injector 7. The ones I have seen are plugged solid with debris rather than having a 1/4' deep hole. I look forward to your results.
Customer: replied 8 years ago.
Is there any way i could have prevented the multiple misfire code if i would not have swapped out the 2 and 4 injector?
If there was a bunch of debris in the fuel rail, you may have distributed it. However, the debris usually stays in #7 and the misfire is strong enough to trick the computer into thinking #2 is missing as well.
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