How Does Low Fuel Pressure Affect Mpg

Eddie 70 · July 11, 2010

Just curious on this one. My new to me truck, 2007 GMT900, is not keeping the pressure up like it should. It will come up to 40 PSI with the truck running and that is about the extent of the pressure. I only checked the pressure with the truck at idle. Turn the truck off and the pressure drops to zero instantly.

Would this affect MPG having low pressure?

Am I going to be able to drive my truck this week with low fuel pressure?

Should I just go ahead and let the dealer replace the fuel pump assembly tomorrow?

Wires · July 12, 2010

Just curious on this one. My new to me truck, 2007 GMT900, is not keeping the pressure up like it should. It will come up to 40 PSI with the truck running and that is about the extent of the pressure. I only checked the pressure with the truck at idle. Turn the truck off and the pressure drops to zero instantly.

Would this affect MPG having low pressure?

Am I going to be able to drive my truck this week with low fuel pressure?

Should I just go ahead and let the dealer replace the fuel pump assembly tomorrow?

You're probably going to lose MPG, driveability, etc. It's going to be running lean with low fuel pressure.

Eddie 70 · July 24, 2010

I finally got a chance to drive my truck after the new fuel pump was put on and yes, gas mileage has improved to the tune of around 20 MPG compared to about 14ish before the pump replacement.

Eddie 70 · August 1, 2010

I should add the 14ish was low 14's on the highway. The just over 20 I got was on a short 20 mile run back from the dealership. After taking the truck on a 250 mile trip it managed about 19.1 MPG.

Eddie 70 · August 3, 2010

Made the same trip this past Sunday. Found out my tires are just a tad taller than stock so I have been running faster than truly indicated. So this week, I set my cruise at 68 MPH indicated. After the trip was done and I had arrived at my destination, the DIC said 21.0 MPG. WOW!! I am very happy about that. Now I just need to get the speedo corrected to indicate correct MPH.