A while back I installed a fuel pressure gauge on the supply line right next to the throttle body. I "hot-wired" the fuel pump and observed that I was getting 11 psi with the eninge off and the fuel pump running. Since it's under the hood, I can't see it while driving. Today, I was messing around under the hood and reached over to goose the engine by pressing on the throttle linkage. It was then that I notice that with the engine idling, the fuel pressure was about 8 psi and when I goosed the throttle, it dropped to about 6 psi or so. Is this the normal range the fuel pressure should be operating in? It just seems a little low to me.

EDIT: forgot to mention it's on a 7747 TBI setup.

 

You want to be around 13 psi with a stock engine. At 6-8 psi your pump is dying. A sure sign is if the fuel pressure goes down when you apply throttle.

I recommend the walbro 255, but im biased

 

Chuck is correct and when you are well modded you want to be able to at least maintain 15psi at WOT without any dips.

 

This is before the fuel regulator, right?

 

Well the regulator keeps the pressure from getting too high. So if your fuel pump can retain 50psi or so of pressure the regulator will keep it at 15. So you will need a fuel system that can hold at least 15psi before the regulator. The regulator will tone it down to what it needs to be but will not increase it.

 

i was gonna duct tape the FP gauge to the windshield and do a WOT run for a mile. i was talked out of it. i guess i am a risk taker.

 

that is how we here in the PNW always check fuel pressure.

hehe watched schultzy89gta's 383 afr/miniram/ud cam combo make the fuel pressure guage look like a vacume gauge