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Fuel pressure/return questions?

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Old 06-18-2008, 10:23 PM
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Default Fuel pressure/return questions?

Hey guys,

I have the car up and running, it's a 98 Z28 take-out with 39,000 miles and a T-56 combination. I am using a Rick's Hot Rod's baffled tank with a 6 AN supply line, and am using the original supply line as my return line off my FPR. Here's an overview of the whole motor:



I checked the fuel return line going to the tank and there was no fuel being returned. I then removed the line going from the main driver's side fuel rail and checked the fuel pressure. It read 50 PSI. There is a metal canister between the fuel input to the fuel rail assemble and the rails themselves. Is this a pressure regulator that is bringing the pressure down to 50 PSI, or am I only getting 50PSI from the pump? Does this fuel pump require fuel for cooling? If so am I now burning the pump up? To clarify, I am only getting 50 psi(+-2 psi) to the front of the drivers side fuel rail. I am currently running a line off the front of that driver's side fuel rail, to my FPR (I can't remember where I got this FPR from), and it looks like this:




What I am wondering: Why is it only getting 50 psi at idle, and what is this solenoid that my supply line runs directly into? Is it just a distribution block?:



Thanks for the help, guys!

-Adam

Last edited by 1fine69; 06-19-2008 at 01:00 AM.
Old 06-19-2008, 07:01 AM
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Don't see any pics?
Old 06-19-2008, 08:32 AM
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Lightbulb My $.02

1. I think that's a pulse dampener.
2. Did you attempt to adjust the FPR? It appears to have a screw in the top, for such adjustment.
3. By removing the dr side line, and installing a gauge, you have taken the regulator out of the system. [unless you have tee'd the ga in.] This will "deadhead" the pump, and, depending on the pump design: Stall the pump,blow lines, or force the fuel to go over the pump's built in relief. [assuming it has 1] You don't mention what pump is used.
4.If #3 is as you have it, you should replumb, so you can have the gauge in line while setting the system up.
5. You DO NOT use hose clamps on braided line...A good way to burn the car down.
6. Maybe a call to the folks you got the tank from???
Old 06-19-2008, 08:32 AM
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Isn't that a returnless fuel rail you've got there? If so, I think you have a return line plumbed to where the fuel feed needs to be, and of course a return isn't needed then at all. That little silver module built into the fuel rail is a fuel pulse dampner, which is common on all types of EFI fuel rail systems. Its not a regulator. Good pictures. Hope this helps.
Old 06-19-2008, 08:35 AM
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Weird must be blocked here cause I get no pics.
Old 06-19-2008, 09:21 AM
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Did you take the shrader valve out of the fuel rail where you have the outlet line connected?
Old 06-19-2008, 10:16 AM
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Not sure what kind of regulator that is, But I would suggest replacing it with either the vette combo or do a aeromotive unit....

also are you returning the fuel from the front schrader port? If so I hope you remove the scharader valve.......

I like this unit
Old 06-19-2008, 12:09 PM
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Originally Posted by Old Geezer
1. I think that's a pulse dampener.
2. Did you attempt to adjust the FPR? It appears to have a screw in the top, for such adjustment.
3. By removing the dr side line, and installing a gauge, you have taken the regulator out of the system. [unless you have tee'd the ga in.] This will "deadhead" the pump, and, depending on the pump design: Stall the pump,blow lines, or force the fuel to go over the pump's built in relief. [assuming it has 1] You don't mention what pump is used.
4.If #3 is as you have it, you should replumb, so you can have the gauge in line while setting the system up.
5. You DO NOT use hose clamps on braided line...A good way to burn the car down.
6. Maybe a call to the folks you got the tank from???
That's the first time I've ever heard that - how would it burn the car down, and what are you supposed to use? I've had this car since I was 13, I definetly don't want it burning to the ground...

Guys, I didn't remove the shrader valve from the end of the fuel rail . Once I get off work tonight, we'll pull that valve, actually USE the FPR this time, and see what she does.

Thanks again for the help!

-Adam
Old 06-19-2008, 12:56 PM
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Talking If..

Originally Posted by 1fine69
That's the first time I've ever heard that - how would it burn the car down, and what are you supposed to use? I've had this car since I was 13, I definetly don't want it burning to the ground...

Guys, I didn't remove the shrader valve from the end of the fuel rail . Once I get off work tonight, we'll pull that valve, actually USE the FPR this time, and see what she does.

Thanks again for the help!

-Adam
the shrader valve was in the rail, when you checked the FP at the main inlet line, and got 50psi, there has to be something relieving the pressure..[Pump is now in a deadhead situation] Leak at the intank pump? Pump has a relief that is operating at 50psi? Pump is toast?
As for burning the car down: Braided line is intended for use w/ the proper fittings installed. That line blows off/leaks, you will be blowing fuel on a hot engine..
Old 06-19-2008, 01:03 PM
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Originally Posted by 1fine69
That's the first time I've ever heard that - how would it burn the car down, and what are you supposed to use? I've had this car since I was 13, I definetly don't want it burning to the ground...
I think what he means is... the whole purpose of braided is cuz it is very strong/resistant to compression/expansion from pressure, so a simple hose clamp might not be enough to get it to seal properly. Braided is meant to have hose fittings, which have a strong steel inner sleeve and then another outer one, with the outer one sinching down on the inner sleeve providing the great seal.
Old 06-19-2008, 01:09 PM
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I would think the 1st area to check is that why there is only 50psi.. even with the Shrader valve in place.. that should lock the valve closed (unless he has done something to push it open in his setup). He can put a pressure gauge on the Shrader valve to check the pressure or tee into the feel line to check.

But with that single feed fuel rail. I would suggest he use a Regulator or Corvette FPR before the fuel Rail and that way put a guage on the Shrader valve to check the pressure.
Old 06-19-2008, 05:02 PM
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Hey guys....

I called Rick's Hot Rods again, the makers of my stainless tank, and Hector gave me a part # of 25163473 for the fuel pump...doing a little research tells me that pump will only deliver 51 PSI - there's my problem right there. I've got a Warlboro 255lph pump at home, so I guess I'll be putting that in tonight.

Rick's said they run that pump on every LS1 vehicle tank they ship out - doesn't seem right to me!

I'll get those hose clamps taken care of too - thanks for the help again guys!

-Adam



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