To keep tabs on what's happening in my motor while spraying, I decided to install both a digital Air/Fuel Ratio gauge and a digital Fuel Pressure gauge. Both gauges are made by Cyberdyne.

The air/fuel ratio gauge is rather easy to find, but the digital fuel pressure gauge is not. JEG'S lists it for $80, but when I called to order it, it was 3-4 weeks backordered! A local import place said they could get it in 4 days, but it would cost $150! Summit carries the A/F meter and many other Cyberdyne gauges, but no fuel pressure gauge...go figure. A little more searching and I happened to come across a local mail order shop via the Net, SpeedPlus Racing Equipment, that had the gauge listed on their website. I called immediately and not only did they actually have one in stock, but it was only $89!

I got the fuel pressure gauge the very next day. I was anxious to install it, but I was still waiting on the A/F ratio gauge from JEG'S. In the mean time, I sized up what seemed to be a fairly easy install. The fuel pressure gauge comes with everything that you need to install it: the gauge, the sending unit, the wire harness, and various electrical connectors.

At this time, I should note that I am unsure of the location of the fuel pressure test ports on PGTs except the '97s. For sure, the '96s do not have one in the same place, if at all. I noticed this on Dan's '96 PGT at the Atlanta meet. So, before ordering the fuel pressure gauge, make certain that you have a place to attach it to the fuel rail. It may be necessary to insert a TEE fitting somewhere in the fuel line itself.

The sending unit (right) is designed to screw right into the fuel pressure test port (after removing the stock bleeder fitting). However, due to its size, it didn't fit well at that location. It was so wide, I had to remove a spark plug wire bracket and even then, it was so tall with the fitting and wire connector it was very close to hitting the hood when it was closed.

You can see the 1/8 NPT fitting on the left side of the unit. In the middle of that there is a pressure sensitive actuator that reads the pressure. On the right side of the unit is the wire connector that is used to run the signal to the gauge.

Fuel Pressure Gauge Installation:

After doing a little measuring and figuring, I headed out to get an 18" long 4-AN line to relocate the sending unit to a more comfortable location. After that, of course, I needed a few more fittings to get everything together. The stainless braided line is a NOS line (P/N 15220). Unfortunately, the shop did not have P/N 15221 which is the same line with RED fittings. The one I purchased had BLUE fittings. The difference is not for looks, but historically, lines with blue fittings are for NOS while red fittings signify fuel. This expenditure was another $30.

Try to stay with me here...this is where those LEGO's my parents bought me when I was younger paid off! In order to connect the 4-AN line to the test port, I needed to remove the stock 1/16 NPT course thread male-to-1/8 NPT fine thread male fitting (bleeding screw went into this). Now I have a 1/16 NPT female end in the fuel rail in which I need to connect a 4-AN female line. A few more fittings will accomplish this: first a 1/8 NPT-to-1/16 NPT coarse thread both sides. On top of that goes a female 1/8 NPT-to-male 4-AN. On top of that goes a swivel 90° 4-AN so that I can aim the braided hose in which ever direction I need to. From there, the 4-AN line is attached and routed to the location of the sending unit. So that the unit sits nicely in an upright position, I added a 90° 4-AN-to-1/8 NPT between the braided line and the sending unit. To save yourself a lot of grief, just about any mechanical fuel pressure gauge installation kit will have all of these fittings plus the braided line in one package. The main problem will be that the shortest line in these kits is 2 feet and sometimes 3 feet...a little too long to duplicate this install, but if you have anything other than a '97 PGT, your install will be different anyway!

OK, I could have simply used a 1/16-to-1/8 NPT fitting and then a 1/8 NPT-to-4 AN right angle instead of building that tower of fittings, BUT that would have put the line much lower, I would have had to run it under the plug wires and laid it against the cover for the pullies. Anyone who has worked with stainless braided lines knows that with vibration added, they are as good as saws on soft material (plastic, aluminum) so I didn't want that. In addition, I couldn't be certain that the the right angle would end up facing the exact direction that I needed.

Once the fuel plumbing is done, simply run the wires inside and to the gauge. Connect to the gauge as shown in the directions. RED=switched +12V, BLACK=ground, BLUE=BLUE from sending unit, BLACK from sending unit=ground.

Air/Fuel Ratio Gauge Installation:

Once the A/F gauge showed up, the install was very easy. The A/F gauge simply reads the signal wire from the stock O2 sensors located in the exhaust system. The most difficult part of the entire install was determining which wire was the signal wire. The gauge only reads when the sensor is at full operating temperature. Since I used the O2 that is directly in front of the cat to read the cumulation of both banks, it takes at least 5 minutes for it to reach this temperature (warming from idle). I also tried the front bank O2 sensor to make certain the gauge was working since it was taking so long to get a reading. That one registered right away.

Note: the O2 sensors located in the manifolds are 3-wire sensors (2 white/1 black). The ones mounted pre and post cat on the '97s are 4-wire sensors (2 white/1 black/1 gray). In both cases the BLACK wire is the signal wire.

Once you find the signal wire, run a wire from there to the gauge and connect as instructed. RED=+12V switched, BLACK=ground, BLUE=signal, PURPLE=dimmer (optional). The dimmer is connected to the dash lights and dims the gauge when the lights are on for night driving.

Gauge Mounting:

OK, all the connections are easy, but where and how do I mount the gauges?

Well, since there are no companies that make A-pillar pods for the PGTs, you have to be creative. I went to the same local performance place that I got the braided line from and picked up a double A-pillar pod for '88-'97 Chevy/GM Full Size Trucks by Gauge Works (P/N 15-100). Cost was $35. Believe it or not, they were the closest fit of all.

I wondered if there was anything else I would ever need the heat gun for that I bought to do the clear corner lamps! Well, here it is. A little patience and some properly applied heat and pressure and viola! An A-pillar pod for your PGT! For whatever reason it looks grey in this photo, I don't know. It's black and looks it in the interior. I am not sure of what other colors they sell, but a simple matching spray paint would easily blend it into whatever your interior color is.

As far as readings go, the diagram to the right shows the scale for the Cyberdyne gauge that I have. I will be heading out to do some serious fuel pressure and Air/Fuel ratio tests as soon as possible. I intend to take readings naturally aspirated with stock fuel system, with NOS and the stock fuel system, naturally aspirated with a in line NOS fuel pump, and with NOS and the NOS fuel pump. I will post my findings on the NOS Notes page as an addendum or replacement to the readings taken with the AutoMeter analog gauge.

This site is made possible by Geocities.