efi fuel pressure at idle

[texhost1]

According to fuel injection.com, for fuel pressure should read about 30 psi at idle. Does that seem correct? When I pull the vacuum hose off the pressure regulator, it spikes to 40 psi. What should your fuel pressure be when you are at 1500 to 2500 rpms? Mine appears to be staying constant as I feather the throttle while in park. Is this correct? Or should the fuel pressure be slowlyincreasing as you give it more gas?

 

[noslo5o]

You should have between 37-39 psi at idle with the vacuum line disconnected from the fpr the pressure should lower when you reconnect the vacuum line. How much psi you have at idle/rpm (with the vacuum line connected) can vary depending on camshaft and ci ie how much vacuum you have.

Short answer your fp sounds fine to me.

 

[Viperwolf1]

That looks about correct. The pressure will increase with a load on the engine, when vacuum drops. Just changing rpm without load won't have much effect.

 

[Steve83]

See the chart near the bottom of this diagram.

Ignore the top.

 

[Broncobowsher]

The pressure regulator maintains a steady pressure differential across the injector. With the engine making vacuum it would pull more fuel through the injector if the pressure at the fuel rail was fixed. To make it easier to program the EFI, the injector flow calculations stick with a fixed flow rate.

In a perfect world there is exactly 43.5 PSI from one side of the injector to the manifold all the time. That is what the injector is trying to achieve. Then there is build variation, wear and the inaccuracy of the gauge itself.

the quick check without specs is mid to upper 30 PSI range at idle with everything hooked up and idling. Low to mid 40 PSI range with the vacuum line unhooked or the engine not running (no vacuum source). If you have that then things are generally fine.