🔧 Colorado - Fuel Pump Replacement

On your Colorado, the fuel pump is part of an in-tank fuel pump module. Replacing it typically requires lowering the fuel tank, swapping the module, then reinstalling everything and checking carefully for leaks.

Difficulty Level: Advanced | Estimated Time: 3-6 hours

Assumption: WT 3.6L uses an in-tank pump module accessed by lowering the tank (no factory access panel).

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⚠️ Safety & Precautions

• ⚠️ Work outside or in a well-ventilated area—fuel vapors are highly flammable.
• ⚠️ No smoking, no sparks, no trouble lights with hot bulbs—use an LED work light.
• ⚠️ Disconnect the battery to reduce spark risk.
• ⚠️ Relieve fuel pressure before disconnecting fuel lines to avoid spray.
• ⚠️ Support the fuel tank with a transmission jack—fuel is heavy and unstable.
• ⚠️ If you must siphon fuel, use an approved fuel container only.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• Fire extinguisher Class B
• Wheel chocks
• Floor jack (rated 3-ton minimum)
• Jack stands (rated 3-ton minimum)
• Transmission jack (specialty)
• Socket set 8mm-21mm
• Ratchet 3/8" drive
• Torque wrench 10-200 Nm range
• Flat trim tool
• Fuel line quick-disconnect tool set 3/8" and 1/2" (specialty)
• Brass drift punch (non-sparking)
• Dead-blow hammer
• Fuel pump lock ring tool (specialty)
• Pliers
• Shop rags
• Drain pan
• Approved fuel container
• LED work light

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Fuel pump module assembly - Qty: 1
• Fuel pump module seal / O-ring - Qty: 1
• Fuel tank strap bolts - Qty: 2 (replace if corroded)
• EVAP line retaining clips - Qty: 1-3 (as needed)

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📋 Before You Begin

• Park on level ground, set the parking brake, and chock the front wheels.
• Drive the fuel level as low as possible (under 1/4 tank is ideal) to make the tank lighter.
• Disconnect the negative battery cable using a 10mm socket.
• Relieve fuel pressure: remove the fuel pump fuse/relay, start the engine, and let it stall; crank 2-3 seconds more, then turn key off.
• Raise the rear and support the frame with jack stands; keep the truck stable before going underneath.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Make the truck safe and relieve pressure

• Use wheel chocks and set the parking brake.
• Use a 10mm socket to disconnect the negative battery cable.
• Use your owner fuse layout and pull the fuel pump fuse/relay, then start the engine until it stalls.
• Place shop rags nearby for any fuel drips.

Step 2: Raise and support the rear

• Lift with a floor jack (rated 3-ton minimum) at the proper lift point.
• Set the frame onto jack stands (rated 3-ton minimum) and gently shake the truck to confirm stability.

Step 3: Support the fuel tank

• Position a transmission jack (specialty) under the center of the fuel tank.
• Use a wood block on the jack pad if needed to spread the load.
• Keep the tank level as it lowers.

Step 4: Disconnect the filler neck and vent connections

• Use a socket set 8mm-21mm and ratchet to loosen the hose clamps at the filler/vent hoses (where accessible).
• Use pliers for spring-style clamps if equipped.
• Gently twist hoses to break them free—avoid tearing rubber.

Step 5: Lower the tank slightly to access lines and wiring

• Use a socket set 8mm-21mm and ratchet to remove the fuel tank strap bolts.
• Lower the transmission jack slowly a few inches to create working space.
• Lower a little, disconnect a little—don’t stretch hoses.

Step 6: Disconnect the electrical connector and EVAP lines

• Use a flat trim tool to release connector locks and EVAP line retainers without breaking them.
• Unplug the fuel pump module electrical connector.
• Disconnect EVAP vapor lines carefully; use shop rags to catch any drips.

Step 7: Disconnect the fuel feed line(s)

• Use a fuel line quick-disconnect tool set 3/8" and 1/2" (specialty) to release the fuel line(s) at the module.
• Wrap the connection with shop rags as you separate it to catch residual fuel.
• Pull straight—side-loading breaks plastic fittings.

Step 8: Remove the fuel tank from under the truck

• Lower the transmission jack (specialty) the rest of the way.
• Slide the tank out carefully; keep it away from sharp edges.

Step 9: Clean the top of the tank and remove the lock ring

• Use shop rags to wipe dirt off the top of the tank so debris doesn’t fall in.
• Use a fuel pump lock ring tool (specialty) to rotate the lock ring off.
• If needed, use a brass drift punch (non-sparking) and dead-blow hammer to tap the ring loose carefully.

Step 10: Remove the fuel pump module

• Lift the module straight up; angle it as needed to clear the float arm (fuel level sender).
• Have a drain pan ready—fuel will drip from the module.
• Remove and discard the old seal/O-ring.

Step 11: Install the new seal and new fuel pump module

• Install the new fuel pump module seal / O-ring in the tank groove.
• Lower the new module into place, keeping the seal properly seated.
• Reinstall the lock ring using the fuel pump lock ring tool (specialty).
• Torque to factory specification (verify in GM service information for your configuration).

Step 12: Reinstall the tank and reconnect everything

• Lift the tank with the transmission jack (specialty) until you can reach the top connections.
• Reconnect the electrical connector, EVAP lines, and fuel line(s).
• Raise the tank fully into position and install the straps.
• Use a torque wrench and socket set 8mm-21mm to tighten the strap bolts.
• Torque to factory specification (verify in GM service information for your configuration).
• Reconnect filler/vent hoses and tighten clamps using a socket set 8mm-21mm or pliers.

Step 13: Restore power and prime the system

• Reinstall the fuel pump fuse/relay.
• Reconnect the battery negative cable using a 10mm socket.
• Turn the key to ON for 5 seconds, then OFF for 5 seconds; repeat 3-4 times to prime the fuel system.

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✅ After Repair

• Start the engine and let it idle while you check under the truck for leaks at the tank, lines, and filler neck.
• If you smell strong fuel odor, shut the engine off and recheck line locks and seal seating.
• Test drive 5-10 minutes, then recheck for seepage again.
• If the check engine light comes on, scan for codes—EVAP line clips and seals are common causes after tank work.

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💰 DIY vs Shop Cost

Shop Cost: $900-$1,600 (parts + labor)

DIY Cost: $250-$650 (parts only)

You Save: $650-$950 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 3-6 hours.

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🎯 Ready to get started?

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