JingleJank

So, the motor runs fine. I have seen some people have a psi gauge attached to their fuel filter. Don't see the point of it being there, but anyways...I was curious what my pressure was at idle. I got a banjo fitting and gauge, installed and at idle it's @ 50psi. I have read that it should be between 38-41psi. What is happening to the motor with it at 50psi? It has the oem fpr and don't know if there is a way to adjust it. Thanks for any insight. I have my flame suit on already haha

cvcrcr99

You can't adjust OEM FPR.

Higher PSI usually means more fuel going into motor. Should be fine, mine always read ~50 psi

You have a straw and you blow bubbles into your drink with it at a particular pressure. Now, increase the pressure... more bubbles, right? Same size straw (or, injector) and higher pressure = more bubbles/fuel

JingleJank

Ok well that's cool. Seems to not be a big deal then. Thanks

B_Swapped93

It's a very helpful thing to have when the car won't start....rules out or points fuel sys issues

JingleJank

^Ahhhhhh...very helpful idea. Makes more sense why one would ad a gauge there. Thanks for that.

sleepyaccord96

the gauge is reading the FUEL pressure AT THE fuel filter which is naturally higher than what is at the rail. The FPR (fuel pressure regulator) knocks the psi down to a specified amount which 38-41 is normal)

The gauge is just to let you know the current psi at filter/pressure nothing more.

correct, you cannot adjust on a oem/stock FPR with the stock ecu and a stock engine setup the oem FPR is best for optimum performance and mpg.

and a constant 50-60psi is normal (at the filter)

JingleJank

Good to know. Thanks all

jbpnoman

Uh, no (kind of). The proper way to test fuel pressure is at the filter. FSM page 11-234. Attach pressure tool. Disconnect FPR vacuum line. Turn key to ON(II). Pressure should read 40-47 PSI. Reconnect FPR vacuum line. Disconnect vacuum line again. Fuel pressure should rise when disconnecting the FPR. Fuel pressure at 50 is out of spec, and may be causing the car to run slightly rich.

sleepyaccord96

we are talking fuel pressure AT the filter where to OP specified where the gauge is. I dont keep a service manual in my pocket at all times so i won't get into oe specs.

If the fuel pressure at the filter was 90psi it still wouldnt make it run rich man, the fuel pressure regulator cuts the psi down to its specified amount.

fuel pressure at filter will never reflect the psi that is served to the injectors, thats why a FPR is there to do one thing and one thing only and that is to cut the psi down and keep it within a range <--there again i do not keep a service manual with me and i am not going to even look into it because op was only curious about the gauge and is currently having no issues with fuel delivery

jbpnoman

I'm an actual, serious mechanic. I have the FSM saved on my laptop, right next to my tuning software. The FPR regulates on a percentage-based rule. It isn't electronic, and it doesn't say "the engine should have X PSI", it's pressure based and says "At X throttle, Y% of fuel pressure gets pushed in". That means too much pressure at the filter correlates to too much pressure at the rail. What happens gets complicated from there.

We're only talking 3 PSI out of spec. It's not that big of a deal, but it might be a sign of a part starting to fail. You're right, the OP isn't saying he has any fuel delivery problems, but he caught it before it became a problem. Diagnostically, I wouldn't even worry about it until a problem springs up.

Does my explanation of how fuel pressure and the FPR work together make sense? I'm not trying to be a smartass, I just want to make sure you understand my explanation.

B_Swapped93

^

If the gauge(at the filter) reads "90psi" no it will not be in the proper spec range at the rail and would cause problems. not that that's the case here.

jbpnoman

At 50, it's still out of spec though. Not enough to worry about cylinder wash, and probably only makes a .5 MPG difference, but it's still off. It's like torquing down an exhaust manifold stud 2 ft/lbs more than you should. Is it technically wrong? Yes. Does it really matter? No.

sleepyaccord96

dude the op simply asked about the gauge... no one ever asked what oe specs are...

I am glad you have a FSM
I am glad you have "tuning software"
I am glad you own a laptop



wow... you're cool.


My shop is a full service shop with lift and all snap on tools. We don't work on vehicles by a book we work on them to diagnose, repair/replace faulty parts, from previous knowledge, not a book. If you need a book to repair a vehicle you shouldn't be working on it.

Torque specs are what you go to a book for as well as specs. But general repair a book should not be needed.

Then again i wish i was a actual, serious mechanic you claim to be.