Fuel Pressure VSV

[Sawbladz]

I'm talking about the VSV under the intake manifold that, according to jetjock, "vents the fuel pressure regulator for about 2 minutes after a start when the coolant is hot. That increases fuel pressure and helps to clear vapor that has formed in the fuel rail during heat soaking when the engine has been off 30-60 minutes. That solenoid connects to manifold vacuum at the vacuum tree located at the front of the intake manifold."

I need to know whether it is necessary to keep if I have an adjustable fuel pressure regulator installed. I have no problems keeping it if it is necessary but I would need to know how it need to be installed with vacuum lines. I am running a FFIM so I won't have the stock mounting points or vacuum line locations. My understanding is that I would want to keep this switching valve and that I would run the vacuum line from the output side of the valve to the vac input on the fuel pressure regulator.

Also, I am looking into plumbing my boost controller and it wants my vacuum sensor to be placed in the vacuum line between the fuel pressure regulator and the intake manifold. If I am correct in my placement of the VSV, where would I put the boost controller vacuum sensor?

 

[jdub]

All an AFPR does is allow some basic tuning ability...i.e. setting base fuel pressure for a given injector size. The Fuel pressure up VSV functions exactly as JJ described - it is a benefit regardless of the plenum used. All it needs is a plenum vac source.

The VSV nipple next to the filter goes to the AFPR - the nipple on the end goes to vac.

For a boost controller, it needs to be a post TB intake manifold port.

 

[Sawbladz]

So the vacuum line that's connected in the following picture needs to run to the fuel pressure regulator and the nipple on the left end needs to go to the intake manifold. I find this interesting because it seems whoever hooked this up before had it backwards or not hooked up at all.

 

[jdub]

That would be correct - take a look at this:
http://www.cygnusx1.net/supra/Library/TSRM/MK3/manual.aspx?S=FI&P=116

Under power the VSV vents to atmosphere (through the filter), the same as if you disconnected the vac line to the FPR, thus causing a FP increase. Power off, the VSV allows vac to the FPR...to do this the vac line must be connected to the nipple on the end (on the left in the pic).