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

 

Welcome from Florida. Do a compression check on #4 cylinder. Better yet do them all.

 

Thanks!

That's next on the list. Will check back after procedure is done.