🔧 Flex - Fuel Pump Replacement

On your Flex, the fuel pump is part of an in-tank fuel pump module. Replacing it usually requires safely lowering the fuel tank, swapping the module, then reassembling and priming the system so it starts normally.

Assumption: Your Flex does not have an interior access panel, so the tank must be lowered.

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

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⚠️ Safety & Precautions

• ⚠️ Work outside or in a very well-ventilated area; fuel vapors are flammable.
• ⚠️ No smoking, no sparks, no drop lights with hot bulbs; use an LED work light.
• ⚠️ Relieve fuel pressure before disconnecting fuel lines to avoid fuel spray.
• ⚠️ Support the tank with a jack before removing strap bolts; a tank can drop suddenly.
• ⚠️ Disconnect the negative battery cable to reduce spark risk.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• Fire extinguisher Class B
• Floor jack (rated 3-ton minimum)
• Jack stands (rated 3-ton minimum)
• Wheel chocks
• 8mm socket
• 10mm socket
• 13mm socket
• 3/8" drive ratchet
• 3/8" drive extension set
• Torque wrench (10–80 ft-lbs range)
• Trim clip removal tool
• Fuel line quick-disconnect tool set (3/8" and 5/16")
• Brass punch and hammer
• Drain pan (at least 2-gallon)
• Shop rags
• Permanent marker

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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 tank seal O-ring - Qty: 1
• Fuel pump module lock ring - Qty: 1
• Evaporative emissions hose clamp assortment - Qty: 1

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📋 Before You Begin

• Park on level ground, set the parking brake, and chock the front wheels using wheel chocks.
• Drive until the tank is as low as possible; a lighter tank is much easier to handle.
• Disconnect the negative battery cable using a 10mm socket and move it aside so it can’t spring back.
• Relieve fuel pressure before opening the system (steps below). A “Schrader valve” is a tire-style valve on the fuel rail used to safely bleed pressure.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Relieve fuel system pressure

• Open the hood and locate the fuel rail Schrader valve (small cap like a tire cap).
• Place shop rags around the valve and position a drain pan under it.
• Carefully press the valve center using a small tool while catching fuel in the rags/pan. Go slow to avoid spraying.

Step 2: Raise and support the vehicle

• Lift the rear of the Flex with a floor jack (rated 3-ton minimum) at the correct rear jacking point.
• Set the vehicle down on jack stands (rated 3-ton minimum) and verify it is stable before going underneath.

Step 3: Remove shields/underbody panels near the tank

• Remove any rear underbody shield or cover blocking the tank straps using an 8mm socket and trim clip removal tool.
• Set fasteners aside in a small tray so nothing gets lost.

Step 4: Support the fuel tank

• Place the floor jack (rated 3-ton minimum) under the fuel tank with a flat piece of wood (to spread load) if available.
• Raise the jack just enough to support the tank’s weight.

Step 5: Disconnect the electrical connector(s) at the tank

• Locate the fuel pump module wiring connector on top/side of the tank area.
• Release the lock tab and disconnect the connector by hand (use a trim clip removal tool gently if needed).

Step 6: Disconnect EVAP and filler/vent connections

• Mark hose positions with a permanent marker so they go back the same way.
• Loosen clamps (if equipped) using an 8mm socket and slide hoses off carefully.
• For quick-connect vapor lines, release the connector by hand; do not twist hard.

Step 7: Disconnect the fuel feed line(s)

• Place a drain pan underneath the fuel line connection.
• Use a fuel line quick-disconnect tool set (3/8" and 5/16") to release the line from the module fitting.
• Pull the line straight off and cap/cover it with a rag to keep dirt out.

Step 8: Remove tank straps and lower the tank

• Remove the tank strap bolts using a 13mm socket, 3/8" drive ratchet, and 3/8" drive extension set.
• Slowly lower the tank with the floor jack (rated 3-ton minimum), watching for any hose or wire you missed.
• Torque note: On reassembly, strap bolts are commonly Torque to 35 Nm (26 ft-lbs); verify for your exact fasteners.

Step 9: Clean the area around the pump module

• With the tank low enough to access the top, wipe dirt away using shop rags.
• Do not let dirt fall into the tank opening once the module is removed.

Step 10: Remove the fuel pump lock ring

• Use a brass punch and hammer to tap the lock ring counterclockwise until it releases.
• A brass punch is a soft metal punch that helps prevent sparks compared with steel tools.

Step 11: Remove the fuel pump module

• Lift the module up slowly and angle it as needed to clear the float arm (the fuel level arm).
• Let fuel drain off the module into the tank for a moment, then move it to the drain pan.
• Remove the old seal O-ring from the tank opening by hand.

Step 12: Install the new seal and module

• Install the new fuel pump module tank seal O-ring into the tank groove by hand.
• Carefully lower the new module into the tank, aligning the indexing marks.
• Install the new lock ring and use the brass punch and hammer to tap it clockwise until fully seated.

Step 13: Raise the tank and reconnect everything

• Raise the tank with the floor jack (rated 3-ton minimum) until it’s close to position.
• Reconnect fuel line(s) by pushing on until you feel/hear a click; tug lightly to confirm it’s locked.
• Reconnect EVAP hoses/lines and tighten clamps using an 8mm socket.
• Reconnect the fuel pump electrical connector by hand until fully latched.

Step 14: Install tank straps and underbody panels

• Reinstall tank straps and start bolts by hand to avoid cross-threading.
• Tighten strap bolts using a torque wrench: Torque to 35 Nm (26 ft-lbs) (verify for your build).
• Reinstall any shields using an 8mm socket and trim clip removal tool.

Step 15: Lower the vehicle and reconnect the battery

• Raise the vehicle slightly with the floor jack (rated 3-ton minimum), remove jack stands, then lower to the ground.
• Reconnect the negative battery cable using a 10mm socket.

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✅ After Repair

• Cycle the key to prime the system: key ON for 5 seconds, OFF for 5 seconds, repeat 3 times before cranking.
• Start the engine and let it idle. Check underneath for any fuel seepage at the tank connections.
• If the check engine light comes on, a loose EVAP connection is common; recheck vapor lines and clamps.
• Top off fuel and re-check for leaks after your first short drive.

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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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