5.7 MFI Fuel Pressure ?

Bluesman123 · February 17, 2004

I've just discovered that I have been running with a flawed fuel filter on a 5.7 MFI vortec. To make a long story short, I ran a few hundred miles with unfiltered gas getting to the MFI regulator and injectors.

I read that the 5.7 MFI pump should be putting out about 63 psi. When I checked (which I have not done before) I found that ... yes, I was getting 63 psi when the system was starting up but that the pressure dropped to 52-54 when the engine was running. It seems to run OK, and a new regulator is about $70 so I don't want to replace it if I don't need to.

Can someone who knows tell me what the fuel pressure should be when the engine is actually running? The service manager at my local GM dealer won't let them "hand out free advice" any more.

Thanks for your help,

Dave

Import Hater · February 18, 2004

As long as you're over 50, you should be fine.

You got the 63psi, because you measured the unregulated pressure. Once the engine is running, the regulator limits it to somewhere in the low 50's. And it should maintain pressure or allow more pressure if ou whack open the throttle.

Rob