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I like boobs!!!
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I've seen this suggested to so many people and am wondering if it's something I should think about. Only problem is I have no freakin clue what it is :eek: or what the benefit is :eek:. Anyone wanna shed some light on the subject? Thanks.
 

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King Trashmouth
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I've seen this suggested to so many people and am wondering if it's something I should think about. Only problem is I have no freakin clue what it is :eek: or what the benefit is :eek:. Anyone wanna shed some light on the subject? Thanks.
Before stal jumps in...

The PPRV is the "positive pressure relief valve." Basically it's a valve that goes between the two pumps and the hat that prevents drainback when the car is sitting to give you quicker start-ups. However as an in-line valve it's a large restriction, can raise your FPDC (fuel pump duty cycle) and the Cobra guys complain of hesitation during shifts due to it.

The only downside is you might need to take some time to let it prime or longer to start.

To delete it you basically put a hose in place of it.

I'm taking a tip from stal and using a 3/8" barbed stainless U-fitting from Kegworks (Buffalo, NY!) and submersible 30R10 fuel hose to replace the line with the PPRV in it.

There's dozens of how-to writeups for it on SVTP.
 

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I like boobs!!!
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Discussion Starter #3
Two pumps? I have a GT. Isn't that just a single pump?
 

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King Trashmouth
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Two pumps? I have a GT. Isn't that just a single pump?
Yeah, I'm just used to the Cobra setup. Basically between the pump outlet and the hat.

I can't seem to find any pictures with a single pump (probably not an issue at lower power outputs) but here's what it looks like on the Cobra:


The PPRV is that white box looking thing between 3 and 4 in the hose.
 

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I like boobs!!!
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Discussion Starter #5
Cool man. Thanks and reps.
 

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If your not maxing out your pump and not having issues with hessitation shifting I would leave it alone. I have gotten away with keeping the pprv delete with a kb frps disk and had no problems at all. I have recently gotten rid of the pprv just for the sake I got new pumps. If the proper bends are not used people have had more problems with kinks in the fuel lines along with tears from using the wrong clamps. Simple answer if it ain't broke don't fix it.
 

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I'm not 100%, but pretty sure only the 03/04 cobra hats have a pprv.
 

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I did it on my cobra tank swap. Notice I dont have the dead spot when trying to take of from the light. Response is better
 

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You dont have to delete the pprv to install a focus pump. its a direct fit. A little more detail to what the PPRV does and what happens when you remove it.

The most simple explanation of the PPRV is a check valve. ALL cars have some sort of PPRV device. Without one all fuel injection cars would be extremely hard to start because they wouldn not maintain any fuel pressure after the prime cycle had ended

The PPRV allows the pump to turn on for a short time to prime the fuel system at start up. When the pump shuts off what holds the pressure? The PPRV. The PPRV on some models also blows off excessive pressure. We're talking when its above 60 or 80 lbs.

What does the PPRV cause hesitation? - picture this. Your hammer down balls out near redline and the fuel pump is running wide open then suddenly you lift and the throttle shuts. What happens? The fuel pressure spikes, the ecu registers this at the FRPS and slows/shuts the pump down but the PPRV holds the line pressure way above the setpoint. As the pump slows down there is nothing to relieve the pressure so the pump continues to slow down thinking the pressure isnt dropping... because the pprv is holding all of the fuel pressure on the sensor. This all happens within a split second of doing a gear change. Now you hammer down and the car falls on its face for a split second. Why? because the ECU thinks there is excessive fuel pressure so the pump slows WAY down and the PPRV holds all the line pressure when your foots is off the throttle. When you hammer down the pump is not running near the capacity needed and there is an IMMEDIATE pressure drop. The car runs out of fuel for a split second and falls on its face. The ECU registers this and sets the pump into wide open to make fuel pressure. The power comes back and all is happy until the next gear change.

Why do only some cars have this problem? It relates to HP being made and how hard the fuel pump is running. If the fuel pump is not running as fast it doesnt spike as hard. The spike isnt as extreme so the ECU response isnt as extreme and there isnt as much pressure drop. This is why mostly 03/04 cobra guys rave about the issue with 400+HP and not bolt on GTs.

Why does removing the PPRV stop the hesitation? When you lift and the fuel pump slows down without the PPRV FUEL IS ALLOWED TO BACKFLOW THROUGH THE PUMP. This reduces line pressure and the fuel pump response isnt as dramatic so the fuel pump continues to run at a higher duty cycle instead of just basically shutting down. Now when you hammer down the pressure hasnt dropped as far because now that fuel is allowed to flow both directions the ECU can properly control the fuel pressure even when the motor isnt consuming hardly any after a WOT gear change.... which means the pump doesnt shut down.

With the PPRV inline pressure spikes and the PPRV HOLDS THE PRESSURE. It can be as high as 90psi. So the ECU freaks out and practically stops the pump. With the PPRV gone the spike isnt as high... the PID fuel pump controls dont slow the pump down as much and you dont have the dramatic pressure drop when back on the throttle.

This is alot to take in and I honestly have a hard time explaining it so that everyone will understand. Not all of this is exactly correct but it will help it make sense to you. If your interested as to why the pump reacts more or less with different pressures I can go into PID controls loops but hold onto your seat. I hope i didnt make this too complicated or ramble too much.
 

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You dont have to delete the pprv to install a focus pump. its a direct fit. A little more detail to what the PPRV does and what happens when you remove it.

The most simple explanation of the PPRV is a check valve. ALL cars have some sort of PPRV device. Without one all fuel injection cars would be extremely hard to start because they wouldn not maintain any fuel pressure after the prime cycle had ended

The PPRV allows the pump to turn on for a short time to prime the fuel system at start up. When the pump shuts off what holds the pressure? The PPRV. The PPRV on some models also blows off excessive pressure. We're talking when its above 60 or 80 lbs.

What does the PPRV cause hesitation? - picture this. Your hammer down balls out near redline and the fuel pump is running wide open then suddenly you lift and the throttle shuts. What happens? The fuel pressure spikes, the ecu registers this at the FRPS and slows/shuts the pump down but the PPRV holds the line pressure way above the setpoint. As the pump slows down there is nothing to relieve the pressure so the pump continues to slow down thinking the pressure isnt dropping... because the pprv is holding all of the fuel pressure on the sensor. This all happens within a split second of doing a gear change. Now you hammer down and the car falls on its face for a split second. Why? because the ECU thinks there is excessive fuel pressure so the pump slows WAY down and the PPRV holds all the line pressure when your foots is off the throttle. When you hammer down the pump is not running near the capacity needed and there is an IMMEDIATE pressure drop. The car runs out of fuel for a split second and falls on its face. The ECU registers this and sets the pump into wide open to make fuel pressure. The power comes back and all is happy until the next gear change.

Why do only some cars have this problem? It relates to HP being made and how hard the fuel pump is running. If the fuel pump is not running as fast it doesnt spike as hard. The spike isnt as extreme so the ECU response isnt as extreme and there isnt as much pressure drop. This is why mostly 03/04 cobra guys rave about the issue with 400+HP and not bolt on GTs.

Why does removing the PPRV stop the hesitation? When you lift and the fuel pump slows down without the PPRV FUEL IS ALLOWED TO BACKFLOW THROUGH THE PUMP. This reduces line pressure and the fuel pump response isnt as dramatic so the fuel pump continues to run at a higher duty cycle instead of just basically shutting down. Now when you hammer down the pressure hasnt dropped as far because now that fuel is allowed to flow both directions the ECU can properly control the fuel pressure even when the motor isnt consuming hardly any after a WOT gear change.... which means the pump doesnt shut down.

With the PPRV inline pressure spikes and the PPRV HOLDS THE PRESSURE. It can be as high as 90psi. So the ECU freaks out and practically stops the pump. With the PPRV gone the spike isnt as high... the PID fuel pump controls dont slow the pump down as much and you dont have the dramatic pressure drop when back on the throttle.

This is alot to take in and I honestly have a hard time explaining it so that everyone will understand. Not all of this is exactly correct but it will help it make sense to you. If your interested as to why the pump reacts more or less with different pressures I can go into PID controls loops but hold onto your seat. I hope i didnt make this too complicated or ramble too much.

Pretty good explanation. When I said you have to delete the PPRV on the focus pump, I meant you have to do it if you are having fuel pump scram issues between hard shifts. If you stay flat-footed while slamming the gears it's not a problem b/c the fuel pressure doesn't spike.

I simply meant that I have a focus SVT pump, and I had to delete the PPRV to fix the fix the hard shift issue. It really isn't a big deal not having the valve. As a habit you will need to run the key to on, wait a couple of seconds, and then crank. I usually turn the key to on, roll the windows down, and when that is done, I crank. It can be a little bit of a hard start when the car is hot and you have just turned it off and are trying to restart. A trade off well worth the issues of detonation and the fact that your car dies between shifts otherwise.

If you are in the tank, I recommend deleting so you never have to worry about it again.
 

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Agree. I tried both and removing the PPVR droped the fuel pump duty cycle about 8%!!!!
 

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GT's and Cobras have them. They are a huge restriction and during shifts causes hesitations because it's releasing pressure back into the tank and takes a while to close back up. On a highly modified car running high fuel pressure because of higher boost levels this can happen often.

When I removed mine I tried using the gates submersible fuel line but it kept wanting to kink and I didn't trust it. So I found a company that sold new clear corrugated submersible fuel line like what is used stock and it worked great. The only reason you can't reuse the stock line is that you either cut it off to remove the PPRV or change pumps. Or it leaks because it's already stretched out. I had to soak the new hose in boiling water and work it on to the pumps, Y fitting, and hat. Including the new clamps I had about $18 invested shipped. Has worked well for over 3 years.

Auto Performance Engineering - Walbro fuel pumps and more
.


An internal pic of the PPRV



I also removed my pulse dampener and upgraded the fuel rail connector to a 10 an Russell Ford EFI connector. These are 2 more huge restrictions. The stock fuel rails are fine.

Stock and Russell fuel rail connector
 

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Stock and Russell fuel rail connector
Do you have the part number for that Jive? I've been wanting to upgrade the lines and have been looking for this for awhile. Also whats a rough guess at he number of feet needed to upgrade the feed line from tank to fuel rails? Any help would be great. Thanks ahead of time.
 
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