Vortec fuel pump

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

V_Kint

OBS Enthusiast
Joined
Apr 29, 2016
Messages
60
Reaction score
19
Location
Georgia
Earlier this year I bought a 1998 Suburban with multiple issues. I had the transmission rebuilt. The distributor was loose and had the worn cam gear issue, so I installed a new one. This didn't cure my rough idle, so I installed the new MPFI spider assembly (something I planned to do regardless). No joy, still running rough. I checked the fuel pressure, and with the key in the on position I got an initial 60 psi spike with an immediate drop to 55. At (rough) idle the gauge showed 50-52 psi. It's worth mentioning that the truck had been hard to start, but it didn't spin over for an extended period as if it was trying to build pressure. It dragged like the timing was off a tooth or had a weak battery and then chugged to life right away.

The result - a new fuel pump cured the issue. The truck now starts easily and runs smoothly. Headache gone.

For what it's worth, I read multiple threads discussing fuel pressure, but I haven't been able to find a definitive answer as to the fuel pressure needed for a Vortec engine. Some say that 60-66 is required, others say that their truck runs fine with less. For mine 50-55 psi wasn't enough to get the job done. It's worth noting that while I read from several sources that the MPFI spider doesn't require as much fuel pressure as the original poppet setup, 50-55 didn't work for it either. My guess is that there is more happening with a bad fuel pump and erratic fuel delivery than can be read on a gauge.
 
Top