Fuel line check valve

[turbov6joe]

I recently upgraded my fuel system with -8 line, and now I'm finding that a one way valve is probably not a bad idea. My opinion is to mount it as close to the tank as possible so the entire line stays filled with fuel. What's your opinion as to the ideal location to mount an in-line fuel check valve?

 

[Jimmysidecarr]

Should we assume you did a PPRV delete when you did the line or GT pumps?

I don't mind it not having the "no drain back feature."

When it's hot and "cranky" I turn the key on and wait 10 seconds and then crank it and it fires right up without extended crank time.

 

[GodStang]

This is where mines at

 

[Tims97SVT]

I had lots and lots of problems with the pprv removed. I kept blowing the frps. Thoes things are not cheap and it will piss you off very fast. I did a run down on the car to see what was going on.

No pprv fuel spikes 70-85psi on start up.
pprv fuel spikes 50psi at max maybe not even that high.

So I dropped my tank and put the pprv back in. I no longer have a problem. What most people fail to understand is the pprv is not only a check valve but its also a pressure relief.

 

[Black306]

Unless your fuel tables are DEAD ON, I wouldn't suggest a check valve. A check valve by itself can contribute to hesitations.

What most people fail to understand is the pprv is not only a check valve but its also a pressure relief.

You are correct about the PPRV functioning as a check valve. However, the PPRV does not function as a typical pressure relief valve. Here is where I describe the function of the PPRV.

http://www.svtperformance.com/forums/engine-tuning-214/281209-frps-6.html#post7581013

Cliff notes: The 'pressure relief' you are referring to will only happen after the pumps are commanded to reduce pressure. If the pumps are commanded to run over ~67psi, they can do it. The 'pressure relief' valve will only reduce pressure in the rails when the pumps are putting out less than rail pressure. Problem is that the 'pressure relief' will only reduce pressure to ~67psi. That design flaw, a calibration of ~67psi, is what I believe to be the principal reason our cars experience hesitations.



Not exactly written for this specific subject of a check valve, but it has good info.

http://www.svtperformance.com/forums/7891861-post6.html

I had lots and lots of problems with the pprv removed. I kept blowing the frps. Thoes things are not cheap and it will piss you off very fast. I did a run down on the car to see what was going on.

No pprv fuel spikes 70-85psi on start up.
pprv fuel spikes 50psi at max maybe not even that high.

So I dropped my tank and put the pprv back in. I no longer have a problem.

Although I don't doubt the PPRV solved your particular issues, I highly doubt it was from the 'pressure relief' portion of the PPRV. I believe that the PPRV helped you in 2 ways:

1) The path for fuel to pass through a PPRV is very small. Similar to a KB disc, pressure spikes were slowed down because of the reduction of fuel volume caused by the PPRV's restrictive path. This gives the computer more time to react to pressure changes. This is not a problem as long as your fuel pump duty cycles are not too high.

2) Another part of the PPRV is what I referred to as a metered leak. The more fuel pressure in the line, the more fuel will come out the metered leak. That is one thing that is eliminated when removing a PPRV and, I believe, does contribute to post-PPRV delete pressure spikes which can damage a FRPS. However with proper tuning, fuel pressure spikes without a PPRV can be significantly reduced and ultimately save a FRPS.

 

[turbov6joe]

I was a bit vague with my mods. Along with the -8 line I did GT pumps, Fore hat, 60's, stage II FPDM, & a KB disc. I intended to run my FPDM from a 12g wire upgrade/30amp relay, but was never able to get the wiring correct. Anyone care to share in detail how they hot wired their FPDM to a 4 pin relay??? Ie...what wire goes to what corresponding pin # on the relay. I tried 2 different ways I found on this site and neither worked. I even bought a new relay thinking mine was bad...notta.

 

[Tractionless1]

PPRV deleted here as well as -8AN line and KB disc. No problems starting and have never blown an FRPS.

 

[Black306]

I was a bit vague with my mods. Along with the -8 line I did GT pumps, Fore hat, 60's, stage II FPDM, & a KB disc. I intended to run my FPDM from a 12g wire upgrade/30amp relay, but was never able to get the wiring correct. Anyone care to share in detail how they hot wired their FPDM to a 4 pin relay??? Ie...what wire goes to what corresponding pin # on the relay. I tried 2 different ways I found on this site and neither worked. I even bought a new relay thinking mine was bad...notta.

Check the link in my sig for a dual FPDM conversion. There is a picture that shows exactly how to wire a relay to an FPDM, including pin numbers. Don't worry about the 2nd FPDM; the wiring for the relay will be the same for a single FPDM.

Also, I wouldn't suggest a 12ga wire from the battery to the trunk. I would recommend a minimum 10ga wire rated for 30A or more.

 

[Parts-is-Parts]

The problem with installing an aftermarket check valve on a returnless setup is this: If you cycle the key too many times without starting the car, it will build up so much pressure that it will lodge the check ball into the housing and cause you to have ZERO Fuel pressure. Dont believe me? Try it yourself.

As for the stock PRVV, it is there to bleed off pressure if you cycle the key, or if the tune is not adjusted to command 40psi regardless of IAT temps. With no PRVV and the disc under the FRPS, you will have no issues.

 

[turbov6joe]

Check the link in my sig for a dual FPDM conversion. There is a picture that shows exactly how to wire a relay to an FPDM, including pin numbers. Don't worry about the 2nd FPDM; the wiring for the relay will be the same for a single FPDM.

Also, I wouldn't suggest a 12ga wire from the battery to the trunk. I would recommend a minimum 10ga wire rated for 30A or more.

What does "CCRM Power" mean?

 

[turbov6joe]

The problem with installing an aftermarket check valve on a returnless setup is this: If you cycle the key too many times without starting the car, it will build up so much pressure that it will lodge the check ball into the housing and cause you to have ZERO Fuel pressure. Dont believe me? Try it yourself.

As for the stock PRVV, it is there to bleed off pressure if you cycle the key, or if the tune is not adjusted to command 40psi regardless of IAT temps. With no PRVV and the disc under the FRPS, you will have no issues.

I can see that happening.

 

[Black306]

What does "CCRM Power" mean?

The CCRM (Constant Control Relay Module) manages power to, among other things, the FPDM. In a stock application, the DG/YE wire supplies power to the FPDM. In a dual FPDM/modified FPDM setup with wiring upgrade from the battery, the DG/YE wire becomes the signal wire to activate the relay.

 

[Tims97SVT]

What does PPRV mean?

 

[GodStang]

What does PPRV mean?

Positive Pressure Relief Valve

 

[Tims97SVT]

Positive Pressure Relief Valve

OK then why am I told that its not a relief valve? Like I think it is?
Also I would think it would work under a lot less then 67psi of fuel psi.
I would like to know exactly how this thing work please.

 

[Black306]

OK then why am I told that its not a relief valve? Like I think it is?
Also I would think it would work under a lot less then 67psi of fuel psi.
I would like to know exactly how this thing work please.

I explained in the link posted above.

http://www.svtperformance.com/forums/engine-tuning-214/281209-frps-6.html#post7581013

Let me know if you have any questions after reading the post.

 

[turbov6joe]

The CCRM (Constant Control Relay Module) manages power to, among other things, the FPDM. In a stock application, the DG/YE wire supplies power to the FPDM. In a dual FPDM/modified FPDM setup with wiring upgrade from the battery, the DG/YE wire becomes the signal wire to activate the relay.

Do I use the DG/YE wire post or pre FPDM?

 

[Black306]

Do I use the DG/YE wire post or pre FPDM?

Pre and post FPDM refer to how a BAP is installed in relation to an FPDM's control of the fuel pumps; they do not have anything to do with the DG/YE power wire.

EDIT: Let me rephrase that. With relation to the relay and powering the system, a BAP does not have anything to do with the DG/YE wire. The DG/YE wire will go from the CCRM to the relay without a BAP inbetween.

However, the popular way to setup a BAP is Pre FPDM. In other words, the BAP feeding power into the FPDM. In that case, the wiring will be like this:

However in a post FPDM setup, the DG/YE wire will still be setup the same at the relay. The difference is that the BAP will be installed between the FPDM and pumps, and the BAP should be used with a HOBBS switch.

 

[turbov6joe]

Pre and post FPDM refer to how a BAP is installed in relation to an FPDM's control of the fuel pumps; they do not have anything to do with the DG/YE power wire.

EDIT: Let me rephrase that. With relation to the relay and powering the system, a BAP does not have anything to do with the DG/YE wire. The DG/YE wire will go from the CCRM to the relay without a BAP inbetween.

However, the popular way to setup a BAP is Pre FPDM. In other words, the BAP feeding power into the FPDM. In that case, the wiring will be like this:

However in a post FPDM setup, the DG/YE wire will still be setup the same at the relay. The difference is that the BAP will be installed between the FPDM and pumps, and the BAP should be used with a HOBBS switch.

I'm not running a BAP. With that being said, should I cut the DG/YE wire before or after it goes into the FPDM and use it to cycle the relay? Where is the CCRM located? If I memory serves me right, I tapped into the DG/YE wire just before the connector that plugs into the FPDM the first time I tried to hook up a relay....notta. I followed your diagram that time, and must have been hooking something up wrong, the pumps would not turn on???

 

[Black306]

I'm not running a BAP. With that being said, should I cut the DG/YE wire before or after it goes into the FPDM and use it to cycle the relay? Where is the CCRM located? If I memory serves me right, I tapped into the DG/YE wire just before the connector that plugs into the FPDM the first time I tried to hook up a relay....notta. I followed your diagram that time, and must have been hooking something up wrong, the pumps would not turn on???

I believe that you may be confused. There is no before or after associated with the DG/YE wire. There is only 1 DG/YE wire running from the CCRM to the FPDM. Not that it matters, but the CCRM is located behind the dash, on the driver's side next to the fuse panel. When dealing with the fuel system, other than a power wire running from the battery to the trunk, all the wires associated with a modified fuel system are in the trunk and on the gas tank; there is no need to mess with wires anywhere else around the car.

Pre and Post FPDM are terms used when describing where a BAP is wired in relation to the FPDM and fuel pumps. Otherwise, those terms are not used.

No, you don't "tap" into the DG/YE wire. You cut it off from the FPDM and use it to cycle on a relay (pin 85). The circuit the relay controls will be power from the battery (pin 30) to the pin where the DG/YE wire use to go to on the FPDM (pin 87). That is shown in my dual FPDM article here:

It can be used for a modified FPDM setup, just ignore the lower FPDM.


Here is another way to look at it, again ignore the lower FPDM plug.