Put in a new Racetronix pump with some edelbrock fuel rails going to an adjustable fuel pressure regulator which is set at 59 PSI.

I have to "prime" the system by turning the key off and back on as the pressure drops fairly quickly. I remove the stock FPR that is in the tank when I put the adjustable on.

I was thinking a toggle switch to actuate the fuel pump relay so I don't have to key on twice. What is everyone else doing?

 

Nobody else has had this issue?

 

I'm not familiar with the F-body fuel system but it sounds like you removed a check valve when you upgraded your parts. You probably need to install a check valve to prevent the system from loosing its prime while the car is not running.

 

I guess the stock FPR acted as a check valve as well, good to know. I'll through a check valve in the pressure line that should keep the fuel there long enough to get a good start.

Thanks man

 

I tossed in a earls check valve

http://www.summitracing.com/parts/EAR-251006ERL

Now, the pressure stays up long enough for me to start it but I still have to be very quick about it when I start it otherwise the pressure drops down to around 20-30 fairly quickly.

Is there a specific way check valves should be mounted when they utilize a flapper? I currently have it mounted vertically close to the fuel rails on a return system as there was a convenient spot for it.

Would it be worth my trouble to relocate it farther back down the feed line?

 

IIRC the pump you bought has a check valve in it, and I would expect that it works. It's most likely the FPR bleeding off. Some FPR's are pretty bad that way, others are very good. But it's probably not the pump.

 

This is the FPR I purchased. Good data about the racetronix pump, didn't know it had a build it check valve. The other possibility is a pinhole in the feed tube. I was pretty careful assembling it so this would surprise me.

http://www.summitracing.com/parts/aei-13129

I'm going to try and move the check valve farther back in the line, in theory the amount of gas leaking through the valve equals L where my current volume with it located nearer to the fuel rails is V.

By moving it farther back I'm increasing the volume, V + A but the amount that leaks past it remains L. If the PSI drop stays the same then I know for sure that the FPR is the issue.

 

That FPR won't have problems like that unless there's crud in it. You don't need two check valves, that's just counterproductive...

 

It's a brand new FPR, brand new pump. It's leaking out of one of them. The checkvalve in the feed line shouldn't hurt anything.

I could plug the FPR at key on engine off so the return has nowhere to go to see if it's the racetronix pump with the bad checkvalve or the FPR. I think I will try that before relocating the check valve.

 

You could have a leaking injector, too. Forgot to mention that...

 

Tested in this evening, it's the FPR letting off the pressure too quickly.

I'm using the evap as a return, when running it is fine and fuel pressure stays at a solid 59 psi. This just happens on startup.

when I turn to key on pressure goes to 50 or so then drops very quickly to 30 within about a second. Is this a sign of a bad FPR or am I simply not dumping enough fuel through it? My pump is the racetronix 255

 

Few adjustable FPRs are designed and tested to hold pressure like you want. Some are better than others, but usually the ball or needle just doesn't form a nice seal in the FPR. Almost all of them are metal on metal and the surface finish doesn't need to be too far off in order to leak like you're seeing.

Short answer : get used to it or buy another FPR.

 

Something else to check out just because I fought with the same thing...

If you used the rubber fuel injection hose in the tank it more then likely has split or come apart. Had this happen to me after a new pump. Ended up buying the nylon hose and haven't had a problem since.

 

2X on the correct OEM nylon hose.
http://www.racetronix.biz/items.asp?...atus=0&Tp=&Bc=

 

I installed one of these on a friends car and it did the same thing. Took it back out and replaced the feed tube and found a crack in the venturi tube and that fixed it. Thats where I would look.