The Crow

I have a 98 K1500 5.7 silverado . It has a misfire at around 2100 and up. The motor has just over 11,000 on it (new reman) back a month or so it started to misfire at highway speeds and 2100 rpms and up. A p300 code poped up put a scanner on it while driving found #5,7,6 misfiring. Checked the plugs found them looking like NEW then checked cap and rotor found a little white corrosion on terminals so I changed the cap and rotor no change at all. Just for HA HA did a compression ck found all at 178 175 psi. Then did new wires and plugs, no change. Then new coil and ignition module no change. Then new fuel injectors unit.(spider type) no change still has a miss at or around 2,100 RPM .A friend told me to CK fuel pressure found it at 48 psi ignition on not running, and 46 psi running. I think fuel pressure is supposed to be 60-66 psi for this VORTEX 5.7 motor. What do i do next change the fuel pump? haven't been able to get the fuel filter off yet a little rust problem but been soaking it with WD40 last few days to see if that will help.. Thanks for any help

kevinkpk

For what it's worth, your misfire to me sounds like lack of fuel, especially given the higher rpm.

The Crow

Thanks, after everything I did I was at my wits end. I feel stupid that I didn't check fuel pressure till the last. I have my doubts that it will be a filter and not a fuel pump. As you can see in my post changed a lot of parts for no reason. But on the bright side every thing but the dist is new.
What do you think the odds are that the filter will come off and not brake my ***** 15 to a 100 odds?

The Crow

Well I am back. Changed the fuel filter and fuel pump pressure wen up to 56-58 psi. (gained 10 psi) still has a misfire on the higher rpm (2100-and up at cruising speed) not sure what to do??

kevinkpk

My recommendations, I'd start chasing vacuum leaks. You truck is 20 years old, is it the same three misfire?