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· 252,000+ Miles
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The community here at urges you to please use caution and seek professional assistance when performing modifications to your vehicle. Before attempting any modification it is advised that you refer to your Colorado or Canyon service manual or contact a certified mechanic as not all GMT355 trucks are the same. The staff and the associated members are in no way responsible for any damages, injuries or other harm inflicted to your vehicle or yourself which may result in attempting these modifications. The posts and content presented on this site reflect in no way the views of or it’s ownership.

A 355nation How To presented by

Project Name
How-To: Install a Fuel Pressure Gauge

Project Description
Adding an aftermarket fuel pressure gauge to your truck!

Skill Level

Project Vehicle
Make: GMC
Model: Canyon
Year: 2005
Engine: 3.5L
Power windows: Yes
Sun Roof: No

Tools Needed
7/8" Combination Wrench
5/8" Combination Wrench
Valve Stem Tool
Wire Strippers
Wire Cutters
Splice Crimper
Long, thin Standard Screwdriver
6-7 Cloth Shop Rags

Project Time
1 hour or less

Project Cost
Fuel Pressure Gauge w/Sending Unit -- $75 to $350
Gauge Cup or Mount -- $5 to $100
1 Amp ATC Fuse -- $0.50
In-Line ATC Fuse Holder -- $3
-4AN Female to 1/8 NPT Female Adapter -- $13
Teflon Tape -- $1
Zip Ties -- $1

So, you want a Fuel Pressure is how.

Warning: As always, let your engine cool and disconnect your positive battery terminal before starting any project under the hood. Then loosen or remove the fuel tank cap before you get started. This will help relieve some of the pressure in the fuel system fuel system and reduce the risk of personal injury.​

Installing the Sending Unit

  1. First, locate your schrader valve fitting on top of the fuel rail towards the front of the drivers side of the engine between the intake manifold and the stock resonator.

  2. Disconnect your hard line from the top of your Fuel Pressure Regulator to the resonator if you have one. Next, disconnect your fuel line from the front of the Throttle Body and move both aside to give good access to the valve, like in my picture above.

  3. Now, take 4-5 of your rags and place them under the fuel rail at the schrader valve and take 1-2 and place them over the top. These are going to catch the gasoline that sprays as you depressurize your fuel rail. Use the flat of the long thin screwdriver to depress the valve and let it spray gas into the rags unit it stops. Remove the gasoline soaked rags and place them in an approved container when the disconnection is complete.

  4. Grab your sending unit and the -4AN to 1/8 NPT adapter fitting. Put your sender into the fine thread side of the adapter and use your 7/8" and 5/8" wrenches to tighten them together until they don't move easily and your sender has at least 3/4 of it's threads inside the adapter.

  5. By now, the gasoline that might have missed the rags should have air dried, so move on to the next stage...removing the schrader valve from the inside of the stem. Place the schrader valve removal tool inside the valve stem and turn until the valve comes out completely. Set it aside the valve stem core or throw it away, you won't be needing it again.

  6. Ok, grab that teflon tape and wrap 2-3 revolutions around the valve stem then screw the sender down hand tight.

  7. Next, grab the 5/8" combination wrench and turn it by the fitting (NOT THE SENDER) another 1/4 turn or until tight. Reconnect your lines to the appropriate ports and make sure you have a good amount of space to fit the electrical connector into the socket.

Installing the Gauge and Wiring

Stage 2 involves installing the wiring and the gauge itself. Figuring out the mounting location and type is totally up to you, I used a three gauge a-pillar pod and a 2 gauge dash pod myself, but find what works for you.

  1. First, run the wiring harness through the grommet in the firewall. (I used the drivers side grommet) and to the gauge, making sure you can reach the sender under the hood with the wiring harness (or just plug it in if you're nervous). My Autometer gauge had a red wire (switched RAP power), a white wire (illumination), and a black wire (ground) plus the wires for the sender. Yours may vary, follow the manufacturer install instructions.

  2. Next, connect the plug to the gauge and fit it to its final location, making sure to leave 2-3" of wire in case you need to remove it later to unplug the harness.

    Place the 1 amp (or whatever the install instructions call for) fuse and your inline fuse holder in line off the RAP wire - I used a blue sea systems 6 space ATC fuse panel since I did 5 gauges at once, plus the LED dimmer) and then connected it to a RAP circuit.

    The white wire goes to Illumination, so you can use an illumination wire off your hazard light switch (or other), an LED dimmer module, or just a RAP circuit. Follow your manufacturers instructions for your particular gauge.

    The black wire goes to a good ground. I made a new one behind the drivers side kick panel, you can connect wherever feels right as long as its a clean metal connection.

  3. Reconnect your battery and reinstall/tighten your gas cap. Now turn the key...remember it won't start right away, you purged the fuel rail so you need to wait for it to get gas back to the injectors. Run for 3-4 minutes to get all the air out of the lines for a more accurate reading. CHECK FOR LEAKS at the sender.

    Your final product should resemble this:

Congratulations! You have a working gauge.

Here's a picture of the receipt with the part number for the fitting from Summit.

· Ride, Boldly, Ride
721 Posts
Wow, that ended up being a lot more straight forward than I would have thought! Thanks for the how-to! :thumbup: Definitely will look into this when I'm back stateside
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