I have a fuel psi gauge hooked up to my fuel rail. The car starts fine and runs fine. I also installed a holley afpr. I have no fuel leaks or anything. But the car will not hold fuel pressure. I start it, it runs at 47 psi (I set at). I turn it off and the pressure drops to about 10 lbs. Any idea's?

 

leaking injector, bad fuel pressure regulator/ improperly installed regulator, fuel pump anti-drain back valve defective

 

It will not hold fuel pressure when you turn it off? I hear this is common with the Holley AFPR. As long as it starts fine, and holds good pressure when running, I wouldn't worry about it. My Holley AFPR is going on next week.

 

Yes mine does the same thing. I installed mine a couple weeks ago.

 

How fast does it leak down?

It seems to me that mine leaks down to ~10 psi after 10 or 15 minutes, which I'd bet is normal. My fuel injectors, fuel pump, and AFPR are all very new, the cold start injector is probably the original one.

Tenpin,
Did you get your engine running well yet?

 

the fuel pressure drops off a couple seconds after the motor stopps running. Thats when it drops down to around 10 psi.

Not yet mnorton, I have a buddy coming over tonight. Were going to finish setting the timing on it, set the fuel pressure, and take out the freeze plug on the throttle body to (cheat) turn the idel up. With the new cam and intake set up it only idels at 500 rpms. So when i put it in gear I have to double pedel it. Once I get it running half way decent. Off to a place called Backwoods racing. There going to put it on the Dyno and custom burn me a chip. They have to do a couple things with the computer also. I took out the A/C.....so the fan runs as soon as I start the car. I'm going to have them adjust that too. There going to work out all the bugs that I dont know how to do. Plus its going to be nice to see what #'s this new cam, Springs, valve seals, Edelbrock intake and runners, ported and polished Plenum, Holley AFPR, new double roller timing set are going to put out. Plus I have new 17" Torque Thrust rims on it to with new tires that havent seen 5 miles on them in the last month!

But back on topic, as long as you turn the key on....the fuel pressure should go up, you turn it off, after a couple seconds, it will drop off using the holley AFPR.

 

I have the Holley AFPR too, and my fuel pressure holds solid for several minutes after the key is turned off.

I think that if your pressure drops off within seconds, that you have a major pressure leak in the system. Maybe a bad injector....

 

I installed all new orings on the fuel rail and on all of my injectors.
I even pinched off the return line (gas line) and it still does it. Ill look more into it tonight.

 

I still believe it's normal with that AFPR. I will let you guys know after I install mine. Loosing fuel pressure that quick through a leaky injector[s] would make it terribly hard to start. I know from experience.

 

How could that be normal? I guess that would mean that the one I have is just a freak?

I wonder if it's more likely that the fuel pump has a check valve that leaks back into the fuel tank, and that most of the time it doesn't get noticed until after installing a Holley AFPR....

 

it drops to about 20...and it takes a few minutes. I've also heard that this is nitorious for the Holley...just wanted to see if anyone else had this problem with the holley.