INSTALLING A VAFPR ON A T.B.I. EQUIPPED CAR

Overview

On T.B.I. equipped cars, one of the first things that you can do, and should do, to compensate for other mods is to modify the fuel pressure.  One problem with a traditional adjustable fuel pressure regulator is that it is a constant fuel pressure increase...the fuel pressure is higher at idle as well as wide open throttle (WOT).  The problem that this creates is that at idle the car usually runs rich (too much gas), and at WOT, the engine usually runs lean (not enough gas...VERY bad).

This is where the vacuum-adjustable fuel pressure regulator comes in.  With the VAFPR, the fuel pressure adjustment depends on the vacuum the engine creates.  Basically, without getting into a big technical discussion, there is a diaphragm inside the fuel pressure regulator.  There is also a vacuum port of the "can" of the VAFPR which you connect to a good vacuum source on the intake.  As the vacuum increases and decreases, the fuel pressure changes accordingly.  This helps the air/fuel ratio stay in a safe range at almost all engine speeds.

 

Finding a VAFPR

GM Adjustable Fuel Pressure Regulator

GM Dealer

GM Part #: 17113186

$82.37 from Dealer

I don't know of any GM vehicle that actually came with a VAFPR on it from the factory.  There must be some out there, because it is a GM part, but I have never heard of them.  So, going to a junkyard and finding one is out of the question.

But, if you go to any local GM dealership, or use one of the internet parts dealers, just give them the part number above, and you will be all set.  It will come with everything you need to convert your old FPR to the VAFPR.

 

Pictures

Here are some pictures you will hopefully find useful if you decide to do this mod to your car:

vafpr-vacuum_line_routing.jpg
512 x 384
55k

This is a picture of the vacuum line going from the VAFPR, into the air cleaner base.  I tried to keep the line as short as possible.  I didn't want it to be in the way of anything, and I wanted to make sure that it didn't disrupt the airflow going into the throttle body.

 

 

 

 

vafpr-vacuum_line_routing_2.jpg
512 x 384
65k

This picture is a little hard to figure out.  When you look at the pic, you can see me holding the air cleaner base.  There is a vacuum line coming from the base, and it runs under the fuel line, under the coil wire, and into a "T" in the vacuum line coming from the intake port.

 

 

 

 

vafpr-vacuum_line_routing_3.jpg
512 x 384
62k

This pic shows the rest of the vacuum line routing.  The main line from the vacuum port in the intake is the one that goes to the brake booster.  Off of that line, there are two "T"s, one that goes to the VAFPR, and the other one (the one closer to the back of the engine) goes into the MAP sensor.  This pic just shows the routing of these things.