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Discussion Starter · #1 · (Edited)
Hello all I am new to this forum. I have a 2001 Chevy S 10 4.3 V6 that just recently started giving me problems coming back home from a 400 mile road trip. After fueling up for the second time I noticed sputtering while on the highway and I basically had to keep my foot to the floor to stay at 70 mph. I got a service engine light and code p0304.

I took my truck to my mechanic friend that evening and he noticed that I had a very consistent misfire in cylinder 4. It was just misfiring the entire time we were talking. He pulled the plug out and noticed that it was black and smelled rich. He suggested that it might be the fuel pressure regulator causing my bad mpg, loss of power, sputtering, and the misfire on cylinder 4 as he believed that the leaking fuel was entering that cylinder from the hole in the plenum.

Fast forward a week to tonight and I attached a fuel pressure gauge to the service valve and discovered that I’m not losing fuel pressure. The pressure goes up to 60 psi when the ignition is switched on and and then stays at 45 but doesn’t go down below 40 when the switch is off. I think that means my fuel pressure regulator is fine, as are my injectors (not leaking gas). The weird thing is that while the truck is running with the gauge on, the needle is erratic, going between 45 and 58 very rapidly. The psi never exceeds 60 while accelerating.

My mechanic now thinks it might be a stuck or bent valve (4th cylinder) or a bad intake manifold leak. What do you guys think?

Thanks
 

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Sounds like your mechanic is some what knowledgeable about these trucks, but would rather guess than do any diagnostics.
 

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The evap for the tank vents on #4. if left unattended it will cause a lean condition and burn #4 intake valve. Ask me how I know
 

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Discussion Starter · #5 · (Edited)
The evap for the tank vents on #4. if left unattended it will cause a lean condition and burn #4 intake valve. Ask me how I know
My mechanic said that’s a very real possibility and will find out when he pokes the camera in the cylinder.

Thanks for the input. I hope it’s not something so serious as a damaged valve.
 
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