Thread: Fuel Pump

Originally Posted by rkm

I agree that the plugs need to be ruled out. I will. But if no one has any more suggestions, if the plugs check out, I suppose I am going to throw a fuel pump at it. Any more suggestions? This is an every day driver, not intended to raise hell in. Our 400 small block is reserved for that.

If you want to rule out the fuel pump look at your O2 sensor and see if it is going lean. Also look at your MAP for vacuum and pressure. I had a situation when I came in this board where the car layed over and I ended up having a check valve in the line leading to the MAP sensor. I checked everything and chased my tail for over a month thinking it was everything from a bad fuel pump to a bad MAF and MAP sensors. I changed the sensors and bought a fuel pump assembly and ended up being a .25 cent T that I needed. I didn't have the Torque app at the time or anything like that. I used a fuel pressure setup and an oil pressure sending unit screwed in where the gauge went on the fuel pressure tester and connected the gauge inside the cabin and used it for a couple of days to see how my pressure was. All that was for nothing Bill ended up spotting the check valve and when I tried it again it was working again so it wasn't the filter I thought it was. I think what you will find is the plugs are bad, but you will be able to tell a lot by playing with the Torque app.

Jeff

I pulled the plugs, they were showing their age for sure, but still in good shape and burning clean, real clean. Installed plugs were NGK R TR55 V-power, replaced with the same.

Still did not fix the issue.

What I learned. This setup was designed by an engineer who works(ed) for GM. The previous owner found and contacted him to custom design these mods with certain requirements in mind. Mainly, to walk that fine line between reliability and performance. And to eliminate the need for headers. Now, if I could find who this was.