When you remove the plastic cap, you will find the top of the connection has a "tapered" (sort of conical) end on it. This is a "-4AN" connection.... a system of fittings that is used widely to contain high pressure fuel and nitrous. You will also see a "core" inside the opening.... that is identical to the "core" in a tire air valve, and will have to be removed with a tire valve core removal tool. There is typically some pressure in the line, and a little bit of fuel will squirt out at you, so make sure the engine is not hot, and hold a cloth around things when you start to unscrew the core. Just press the core in, with the tip of your finger, with a rag wrapped around the valve to relieve the pressure.

Now that you have the core of the valve out, you have two choices on connecting the pressure sensor to the Schrader:

1. (Not Recommended) Use a hard fitting – an elbow from Earls - that changes the –4AN to 1/8” NPT male, and then add a 1/8” NPT “coupling” from Earls to hook the elbow to the pressure sensor. If you decide to mount the sender directly on the Schrader valve, get and Earls 90-deg adapter:

EAR-923104.

Then just get the 1/8" NPT coupling, or a similar fitting from Earls:

EAR-991001.

The thing I do not like about connecting the sensor directly to the Schrader connection is... 1) when you tighten the -4AN fitting on the Schrader, you have no control over which way it will be pointing when you are all tightened up. An -AN type fitting seals very well with minimum torque. Too much torque, and you damage the seal, or worse yet, you break the Schrader connection off the fuel line... VERY expensive to repair. I believe the Schrader connection is only “swaged” onto the fuel line. And 2) now you have the weight of the sender on the connection, and possibly very close to the cowl, which it might hit if the engine torques over on acceleration.

2. (Recommended) Use a swivel fitting to get the connection away from the cowl, and easy to position. Then run a braided S/S hose to the pressure sensor, in a remote location. The sensor is away from the cowl, and can be positioned away from the heat.

I suggest the NOS part # 17535 -4AN 90-degree swivel fitting. - that is what you see screwed onto the Schrader connection in my photo. That lets you tighten the fitting and point it in any direction, and gets it angled so it is parallel to the cowl, rather than point up into it. Then run a short -4AN braided hose to the sensor, which can be located out of the way. NOS makes a 24" -4AN hose with 1/8" NPT threads on the other end. Use a brass coupling to connect it to the sensor. Or, use a brass "tee" for multiple connections, as described below. Check on eBay.... there are hoses available in custom lengths, with the -AN and NPT connections, for about 1/2 of what you will pay for a hose from NOS.

NOS-17535 for the 90-deg swivel fitting.
NOS-15230-1 for a red fitting 24" -4AN hose, or
NOS-15230-2 for a blue fitting hose.

Now, with the hose in place, you can tuck the pressure sender out of the way, say behind the PCM, which is where the rubber grommet is that you are going to route the wires through, to get them inside the car.

Some people want to connect two or more devices to the Schrader connection.... a fuel source for a wet nitrous system, or a fuel pressure safety switch for a nitrous system, or a small extra pressure gauge that will be visible under the hood while you are adjusting your pressure regulator. If you want to connect two devices to the hose, just get a brass 1/8" NPT "tee" with 3 female 1/8" NPT connections... screw the hose into one end, the pressure sender into the other end, and the extra device into the remaining opening.

You can get the fittings direct from NOS by calling them, or from Summit or JEG's online. All you need is the part #'s, and you put them in the "search" field on Summit with the NOS or Earls vendor code in from of it, and it will give you the price and allow you to order online.