Fuel-pump replacement on a 2006–2008 Mercury Mountaineer 4.0L V6 begins with diagnosing hard starting, stalling, loss of power or an inaccurate fuel gauge. A stored P0191 fuel-rail-pressure sensor A circuit range/performance code requires pressure, sensor and circuit checks; it does not prove the pump has failed. This guide explains product fitment, preparation, replacement and final checks using the specific early-build 2008 RWD example below.
Which Mountaineer does this guide cover?
This guide focuses on the 2006–2008 Mercury Mountaineer 4.0L V6. The written example is an early-build 2008 Mountaineer, through November 27, 2007, with a removable screw-on fuel cap, 4.0L SOHC V6 gasoline engine, rear-wheel drive, 5R55S automatic and original one-piece rear driveshaft. Confirm that configuration before using the procedure. Late-build capless fillers, AWD, V8 and Sport Trac access require their own preparation and service information.
These are planning allowances for a diagnosed pump fault, sound original tank and fittings, and access to a staffed hoist bay. Equipment, facility charges and repairs to corrosion or damaged lines are additional.
Featured replacement module
A-Premium FP0079, ASIN B075HXF5MC, is a 12-volt gasoline fuel-pump module. The selected item is one assembly with a level sender, float, strainer and wiring. Listed original-equipment references include 6L2Z-9H307-A, 6L2Z-9H307-AA and 7L2Z-9H307-A; FG0874 is an additional interchange reference.
Check the delivered contents before dismantling. The selected listing describes a sealing ring and its photograph shows a green O-ring, while the manufacturer’s gasket field says none is included. Have one correct new tank seal ready: the 2008 Mountaineer catalog identifies 4L3Z-9276-AA. A supplied seal can satisfy that requirement only when its fit and condition are confirmed. A separate metal retaining ring is not promised; 4L2Z-9C385-AA is the cataloged replacement when needed.
The manufacturer excludes a pressure sensor. Match the original module’s flange, sender, float travel, plugs and fuel connections with the delivered part. Do not force mismatched fittings or alter wiring to fit an unconfirmed module.
View the Mountaineer fuel-pump module
Product applications and the 2009 build-date change
The product catalog lists these gasoline applications. The engine descriptions below use 4.0L V6 and 4.6L V8, as identified by Ford. This table describes part applications; the repair steps remain specific to the stated early-build 2008 RWD Mountaineer.
| Vehicle and listed trim | Model years | Engine | Body |
|---|---|---|---|
| Mercury Mountaineer — Convenience | 2006 | 4.0L V6 | Sport Utility |
| Mercury Mountaineer — Luxury | 2006 | 4.0L V6 | Sport Utility |
| Mercury Mountaineer — Base | 2007–2009* | 4.0L V6 | Sport Utility |
| Mercury Mountaineer — Premier | 2007–2009* | 4.0L V6 | Sport Utility |
| Mercury Mountaineer — Premier | 2006 | 4.6L V8 | Sport Utility |
| Mercury Mountaineer — Luxury | 2006–2009* | 4.6L V8 | Sport Utility |
| Ford Explorer — XLS | 2006 | 4.0L V6 | Sport Utility |
| Ford Explorer — Eddie Bauer | 2006–2009* | 4.0L V6 | Sport Utility |
| Ford Explorer — Limited | 2006–2009* | 4.0L V6 | Sport Utility |
| Ford Explorer — XLT | 2006–2009* | 4.0L V6 | Sport Utility |
| Ford Explorer — Eddie Bauer | 2006–2009* | 4.6L V8 | Sport Utility |
| Ford Explorer — Limited | 2006–2009* | 4.6L V8 | Sport Utility |
| Ford Explorer — XLT | 2006–2009* | 4.6L V8 | Sport Utility |
| Ford Explorer Sport Trac — Limited | 2007–2009* | 4.0L V6 | Crew Cab Pickup |
| Ford Explorer Sport Trac — XLT | 2007–2009* | 4.0L V6 | Crew Cab Pickup |
| Ford Explorer Sport Trac — Limited | 2007–2009* | 4.6L V8 | Crew Cab Pickup |
| Ford Explorer Sport Trac — XLT | 2007–2009* | 4.6L V8 | Crew Cab Pickup |
*2009 requires an additional check. The Mountaineer and Explorer catalogs assign the 7L2Z module through January 20, 2009, and a different AL2Z-9H307-AA assembly from January 21. The Sport Trac catalog labels its older module through January 21; have a Ford parts supplier resolve vehicles at that change using the VIN and original part number. Do not assume the featured module fits every 2009 vehicle.
The manufacturer does not state tank-capacity, transmission or drivetrain restrictions in these rows. Verify the VIN, build date, original reference and actual connections before ordering; an absent restriction is not a guarantee for a modified or different configuration.
Plan the fuel handling and lifting first
Use an equipped hoist bay, a trained lift operator and an assistant. The rear driveshaft and drained tank must be supported throughout removal. The tall tank jack/cradle in the table is for lift-height work. Do not cut a floor access opening or work under a vehicle supported only by a lifting jack.
Cool the engine and exhaust, ventilate the bay, wear splash goggles and gasoline-compatible gloves, and keep a Class B-rated extinguisher accessible. Keep smoking, flames, sparks, hot work and personal electronics out of the fuel work area. Use approved gasoline transfer/storage equipment with its specified bonding and grounding provisions.
This walkthrough uses the early-build 2008 screw-cap filler and an engine that can idle for the factory pressure-relief sequence. A non-running engine needs professional controlled depressurization before entering the repair. Late capless vehicles need their own filler-access preparation. Stop for unsafe frame/straps, a damaged tank, broken fittings or burned connectors.
Confirm the fault before removing the tank
Have a technician record codes and relevant operating data before battery disconnection. P0191 identifies a fuel-rail-pressure sensor A circuit range/performance problem. Low or high fuel pressure, wiring, the sensor, its vacuum reference and an empty tank are among the possible causes; the code does not condemn the pump.
For a hard start, stall or loss of power, have fuel quantity, electrical supply/control and actual delivery checked. Ford’s 2008 Mountaineer 4.0L specification is 207–276 kPa (30–40 psi) with the key on/engine off and with the engine running. The technician must use the correct measurement method; a scan-tool pressure value is not automatically the same as a gauge reading.
An inaccurate gauge also needs sender-circuit diagnosis. The module includes a sender and float, but it will not repair damaged vehicle wiring or a separate pressure-sensor fault. Keep advanced electrical, pressure and EVAP testing with an equipped technician.
Tools, replacement hardware and supplies
Use an existing equipped hoist bay with an assistant and the complete compatible gasoline-recovery system. Match actual fastener heads, drive sizes and torque ranges. The 112 N·m shaft bolts need the separate high-range wrench and 12-point socket. Buy four new bolts and have one correct new seal ready; existing suitable tools, clean supplies and separate drip trays are sufficient.
| Tool or Supply | Exact Product | Product Link | Purpose and Selection Check |
|---|---|---|---|
| Installed vehicle hoist and equipped service bay | BendPak 10AP two-post vehicle lift; existing suitable installed equivalent acceptable — 10AP / 5175304 | View exact hoist requirements | Use an installed hoist rated 10,000 lb total and 2,500 lb per arm at approved contacts with locks engaged. Verify load, balance and clearance; the bay also needs a stable padded shaft-resting surface. |
| Grounded-wheel chocks for lift preparation | Fasmov solid rubber wheel chocks, two-pack | View two-pack wheel chocks | Place the two rubber chocks ahead of and behind a grounded tire during initial lift preparation. Check full contact and dry, level footing; use Park and the parking brake until the controlled hoist sequence begins. |
| Under-hoist tank-support jack | Sunex 1000 lb telescopic transmission jack — 7793B | View under-hoist tank jack | 1,000 lb capacity; minimum saddle height 35 inches before the adapter. Use in the hoist bay with the secured 7706 cradle, suitable working clearance and an assistant guiding the drained tank. |
| Strapped empty-tank cradle | Sunex fuel tank adapter — 7706 | View matching strapped tank cradle | For EMPTY tanks up to 40 gallons. Secure its mounting system to the 7793B, position padded supports and use both straps and grounding provisions; verify stable contact before releasing tank supports. |
| Metric sockets, ratchet and extensions | TEKTON 3/8-inch drive 6-point socket and ratchet set — SKT15201 | View metric socket set | 3/8-inch drive, six-point 6–24 mm sockets with ratchet and straight extensions. Match each actual fastener head; a driveshaft fastener requiring another profile needs its separately specified socket. |
| Low-range torque wrench | EPAuto 1/4-inch drive click torque wrench, 20–200 in-lb | View low-range torque wrench | 1/4-inch drive; 20–200 in-lb (2.26–22.6 N·m) covers the 3 N·m filler clamp, 6 N·m shield nuts and 7 N·m battery ground terminal. Use the listed coaxial adapter and correct socket. |
| Low-torque drive adapter | TEKTON 1/4-inch female to 3/8-inch male drive adapter — SHA04101 | View correct drive adapter | 1/4-inch female input accepts the low-range wrench; 3/8-inch male output accepts the sockets. Keep both fully seated. This coaxial adapter changes drive size without creating an offset lever arm. |
| Tank and shield torque wrench | EPAuto 3/8-inch drive click torque wrench, 10–80 ft-lb | View tank and shield torque wrench | 3/8-inch drive; 10–80 ft-lb (13.6–108.5 N·m) covers 48 N·m tank fasteners, the 20 N·m heat shield and optional 40 N·m skidplate. The selected metric sockets fit directly. |
| Factory-compatible gasoline recovery tanker | Ford Rotunda 30-gallon hand-operated fuel tanker — 034-00002 | View factory tanker specification | Have the equipped bay supply this 30-gallon manual tanker with its matching drain-hose connections and filler-pipe suction tube. Verify free capacity and required bonding/grounding before recovering gasoline; use a documented compatible equivalent if necessary. |
| Factory tank-draining hose | Ford fuel tank drain hose — 310-F013 | View exact tank-drain hose | Use 310-F013 with the compatible tanker after disconnecting the filler hose, as illustrated. Confirm complete, sound hose connections; do not force an ordinary siphon through the filler check valve or improvise a reducer. |
| Clean temporary fuel-line caps | Lisle Master Line Stopper Set — 67000 | View fuel-line caps and stoppers | Clean stoppers cover 1/8–1/2 inch; caps are 5/8 and 3/4 inch. Match the actual depressurized openings without force, protect against dirt and remove every cap before reconnection. |
| Splash eye protection | 3M chemical-splash goggles — 91252H1-DC-10 | View splash goggles | Wear fitted chemical-splash goggles before pressure relief or fuel disconnection. Check the lens, strap and seal; keep your face away from possible liquid discharge and fuel-wet components. |
| Gasoline-compatible hand protection | Ansell AlphaTec Solvex nitrile chemical gloves; choose a fitted size — 37-175 | View exact glove and sizes | Choose fitted 37-175 nitrile gauntlets and check the actual gasoline blend against the chemical guide. Avoid sustained contact; replace contaminated or damaged gloves. Test values do not establish safe wearing time. |
| Accessible Class B extinguisher | First Alert rechargeable home/workshop fire extinguisher — HOME2PRO | View Class B-rated extinguisher | UL 2-A:10-B:C includes flammable-liquid coverage. Keep a ready extinguisher accessible near a clear exit, and remove ignition sources and provide ventilation before opening the fuel system. |
| Small-spill absorbent | New Pig Universal Light-Weight Absorbent Mat Roll, 15 inches × 50 feet — 25201 | View gasoline-compatible absorbent roll | Manufacturer-rated for gasoline and common automotive fluids. Use sections for small drips within the catch area, then promptly place saturated material in the self-closing waste can away from ignition sources. |
| Separate gasoline and transmission drip trays | FloTool galvanized metal drip tray, 25 × 36 inches — 11430 | View exact metal drip tray | Use two separate 25 × 36-inch metal trays, or suitable ones already owned: one for gasoline and one for transmission drips. Keep liquids separate, prevent overflow and transfer them to appropriate containment. |
| Residual-gasoline safety can | Eagle five-gallon Type I red gasoline safety can with funnel — UI50FS | View residual-gasoline safety can | Five-gallon red Type I gasoline can with closing lid and flame arrester. Maintain enough free capacity for residual liquid and follow fill limits; fuel-wet cloths belong in their separate waste can. |
| Fuel-wet cloth waste can | Justrite foot-operated oily-waste can, 6 gallons — 09100 | View self-closing cloth-waste can | Six-gallon steel can holds fuel-wet cloths and absorbent. Keep its self-closing lid shut between deposits and arrange appropriate disposal; collected liquid gasoline belongs in approved fuel containment. |
| Clean lint-free wipes | Texwipe AlphaWipe dry polyester cleanroom wipers, 9 × 9 inches — TX1009 | View exact lint-free wipe reference | Use fresh dry lint-free wipes without wax, polish or presaturation. Keep fibers out of openings and move wet wipes promptly to the waste can; existing suitable clean cloths are sufficient. |
| Driveshaft torque wrench | EPAuto 1/2-inch-drive click torque wrench, 10–150 ft-lb | View driveshaft torque wrench | 1/2-inch drive; 10–150 ft-lb (13.6–203.5 N·m) covers the four new rear flange bolts at 112 N·m. Fit the listed twelve-point socket directly and tighten evenly in the specified cross pattern. |
| Driveshaft flange socket | TEKTON 1/2-inch-drive × 12 mm shallow twelve-point socket — SHD22312 | View exact driveshaft socket | 12 mm twelve-point opening, 1/2-inch drive. Confirm the actual original and replacement bolt heads, seat fully and connect directly to the driveshaft torque wrench; the six-point general set cannot replace this profile. |
| Manual breaker bar | TEKTON 1/2-inch-drive 24-inch breaker bar — SBH00224 | View manual breaker bar | 1/2-inch drive, 24-inch length accepts the driveshaft socket and 310-123 ring wrench directly. Apply controlled manual force with the component supported; do not use impacts or add an extension pipe. |
| Manual flange-separation tool | TEKTON 12-inch angled-end handled pry bar — LSQ42012 | View manual flange pry bar | Use this 12-inch angled bar manually only at the illustrated flange separation gap, with the shaft controlled. Do not hammer it, lever against sealing surfaces or use a small precision screwdriver as a pry bar. |
| Driveshaft indexing marker | Sharpie oil-based paint marker, white, medium point, one count — 35558 | View white indexing marker | White medium-point paint makes visible driveshaft index marks. Mark the specified external locations before separation, let the marks dry and keep paint off splines, seals and mating faces. |
| Four new rear driveshaft flange bolts | Ford rear driveshaft flange bolt — N800594-S100 | View exact replacement flange bolt | Obtain four new VIN-matched N800594-S100 bolts for the worked rear flange. Check the package quantity and actual head; preserve supplied coatings and apply the verified 112 N·m cross-pattern tightening procedure. |
| New pump-to-tank seal | Ford fuel pump module seal — 4L3Z-9276-AA | View exact new module seal | Have a correct new seal ready before opening. Check FP0079’s delivered contents and seal fit; if unsuitable or missing, obtain VIN-matched 4L3Z-9276-AA. Keep it separate from the metal retaining ring. |
| Metal retaining ring — if replacement is required | Ford fuel pump module retaining ring — 4L2Z-9C385-AA | View exact metal retaining ring | Match the VIN and tank’s retaining hardware before ordering. FP0079 does not promise this metal ring; use 4L2Z-9C385-AA when the specified inspection or replacement rule requires a new ring. |
| Safety blowgun and regulated bay air | Milton safety blowgun with 4-inch extension — 131 | View exact safety blowgun | Use the bay’s clean regulated air and compatible hose with the 1/4-inch NPT inlet. Keep safety vents unobstructed and wear goggles; clean closed fittings only, never open fuel ports. |
| Clean engine oil for quick connectors | Motorcraft SAE 5W-30 synthetic blend gasoline engine oil, 1 quart — XO-5W30-Q1SP | View clean engine-oil reference | Use a few fresh clean drops on the mating tube ends as specified. Suitable clean engine oil already on hand is sufficient; keep dirt out and do not substitute used oil or spray lubricant. |
| Fuel-pump retaining-ring wrench | Ford Rotunda fuel tank sender unit wrench — 310-123 | View exact Ford ring wrench | Exact OEM 310-123 connects to the 1/2-inch breaker bar. Fully engage it with the secured tank’s ring and turn to the specified locked stop; do not use impacts, a hammer or a guessed torque. |
| Passenger trim release — if needed | Lisle Wedge Assortment Set, five pieces, orange — 69620 | View nylon trim wedges | Use a nylon wedge only if needed to release the passenger scuff and kick-panel clips gently. Support the trim near each clip; do not pry on the IFS electrical connector or fuel-line retainers. |
| Water-based vapor-hose lubricant | AGS Ru-Glyde rubber lubricant, 12 fl oz bottle — RG-12 | View water-based vapor-hose lubricant | Apply a small amount to the rubber vapor-hose joints specified in the canister procedure. This water-based product contains no petroleum or silicone; keep it out of the canister and off the module seal. |
DIY and professional cost planning
The figures below are illustrative U.S. dollar allowances, not current product prices, flat-rate labor times or shop quotes. Obtain an itemized estimate after diagnosis.
| Expense | Planning allowance | Included assumptions |
|---|---|---|
| Replacement module | $90–160 | One correctly matched aftermarket module |
| Seal, new shaft bolts and supplies | $70–170 | New correct seal, four new flange bolts, containment/cleanup supplies and a retaining ring only if needed |
| DIY parts and supplies | $160–330 | Existing suitable hand tools and safety equipment assumed |
| Equipment and facility | Separate quote | An equipped hoist bay, tank support and approved gasoline transfer equipment are outside the parts budget |
| Professional labor example | $360–900 | Illustrative 3–5 billed hours at $120–180/hour; actual billing depends on the vehicle and shop |
| Professional installed example | $540–1,320 | Labor plus $150–350 parts and $30–70 supplies; diagnosis, tax and additional repairs are extra |
Buying specialized equipment solely for this job can eliminate the apparent DIY saving. Rusted tank attachments, damaged quick connectors or a driveline defect change the scope; a sound diagnosis and an equipped installer may be the more practical choice.
Replacement steps: early 2008 Mountaineer 4.0L RWD
Use Ford’s exact tank procedure and module instructions for this configuration. The following sequence retains a sound original tank, canister, vapor plumbing and one-piece rear driveshaft.
1. Prepare the part, vehicle and pressure-relief access
Confirm the VIN/build, screw-on filler cap, RWD shaft and delivered module. Have the new seal and four new N800594-S100 rear flange bolts ready. On the level hoist approach select Park, set the parking brake and chock the wheels. With ignition off, release the internally clipped front-passenger scuff plate and kick panel using the trim tool; reposition the lower weatherstrip only as needed. Disconnect the inertia fuel shutoff (IFS) switch connector.
2. Relieve fuel pressure, then isolate power
With everyone clear, start the engine and let it idle until it stalls. Crank for approximately 5 seconds, then switch ignition OFF. Leave the IFS connector disconnected until the repair is complete. If the engine cannot run this sequence, stop for professional pressure release; cap removal or silence from the pump does not establish a depressurized fuel rail.
Have the operator secure the vehicle at Ford’s approved hoist frame contacts, checking capacity, balance and clearance; do not lift at suspension arms, joints or bumpers. Select Neutral through the normal interlock before battery isolation, with the vehicle restrained against movement. Switch ignition off and disconnect/isolate the negative battery cable. The positive cable can remain connected. Raise and lock the hoist before working below; release the parking brake to rotate the shaft only with the wheels clear and vehicle secure. Let heated components cool before handling fuel.
3. Mark and remove the one-piece rear driveshaft
Index-mark the shaft against the transmission extension housing and its rear flange against the pinion flange. Have the assistant support its weight. Fully seat the 12 mm 12-point socket, remove the four rear flange bolts and discard them.
If the flange is tight, use the pry bar only at the factory separation recess between the flange yoke and pinion flange; do not hammer the shaft or pry on a joint, tube or seal. Guide the shaft from the extension housing without dropping it. Mark the exposed output shaft to match the housing mark, preserving the original spline relationship.
Rest the shaft on a clean padded support. Protect the transmission opening externally from dirt and catch any drips separately from recovered gasoline; do not push cloth into it or fit a guessed plug. If transmission fluid is lost, have its level properly checked and corrected before operation.
4. Drain the filler pipe, then the tank
Follow the two-stage factory draining procedure. Slowly release the screw-on fuel cap, waiting for any hiss to stop. Insert the suitable fuel-drain tube into the filler pipe until it stops; do not force it through an obstruction. Connect the approved storage tanker and remove as much fuel as possible from the filler pipe.
Catch the remaining fuel while loosening the filler-pipe hose clamp and separating the connection. Use the 310-F013 drain attachment with the gasoline tanker to siphon the tank through the exposed inlet. Verify receiving capacity and follow the equipment’s grounding instructions. Drain the tank before loading a cradle rated for empty tanks; keep reusable fuel in clean, approved closed containment. Protect the larger filler opening externally with a clean covering; do not stuff a wipe or force a small stopper into it.
5. Free the external lines and protective covers
Record hose routing. Clean each closed quick-connector retaining area with regulated safety air, then use clean wipes; never blow into an open fuel system. Shield openings against residual liquid and cap each freed line.
Disconnect the filler vapor tube from the FTP/vapor-tube assembly and the vapor hose from the canister vent valve. Remove the fuel-filter heat shield and then its separate filter shield. Disconnect the filter outlet quick coupling and the FTP/tube-assembly connection to the chassis vapor tube. If fitted, support and remove the tank skid plate: four bolts and one nut.
Identify each retainer before release. Ford’s quick couplings use a locking tab/pressed clip, push button, releasable latch or compressed clip legs according to type. Operate the fuel-line retainers by hand; do not pry them with the trim tool or a screwdriver. Stop for a damaged or unfamiliar fitting rather than forcing it.
6. Lower the drained tank under control
Center the tank on the correctly assembled jack/cradle and secure its restraint straps. With the support taking the load, remove the rear support-strap bolt and front support-strap nut, then free the straps without bending them. Lower only far enough to reach and unplug the pump’s vehicle electrical connector.
Confirm every line, harness and attachment is free before lowering farther. Guide the tank level with the assistant; it must never hang from a hose, wire or remaining strap.
7. Remove the canister and separate pressure-sensor tubing
On the supported tank, detach the EVAP canister enough to reach its FTP-tube quick coupling and rubber vapor hose. Disconnect both and remove the canister. Lift off the tank’s molded shield, preserving all factory insulation and attachment features.
Unplug the separate FTP sensor, release its three quick couplings to the pump module and vapor vent valves, and lift the sensor/tube assembly clear. Keep that serviceable assembly for reuse; FP0079 does not supply it. Disconnect and remove the pump’s fuel-supply tube, preserving routing and clips.
8. Remove the old module and inspect the sealing area
Clean the closed tank top, note the module’s orientation and stabilize the tank. Fully engage Ford 310-123 (SR-015312) with the manual breaker bar and turn the cam ring counterclockwise. Control the module as the ring releases, then lift it carefully, protecting the float arm and strainer. Catch residual fuel and discard the old O-ring.
Inspect the tank groove, locking features and retaining ring. Replace a corroded, distorted or damaged ring; defective tank locking features require repair before proceeding. Remove loose contamination without allowing debris into the tank. Compare the old and new module before installation.
9. Install the new seal and lock the module
Seat one new, correct O-ring flat in the clean groove, without twisting or stacking it. Guide the module in its correct orientation, keeping the float and filter clear, and hold it squarely down against the seal. Keep the seal clean and undamaged; do not add sealant or an unspecified lubricant.
Install the ring using 310-123 manually clockwise until the cam ring reaches its stop and is fully locked. Check full engagement and that the module remains properly seated. Ford specifies this mechanical endpoint, not a numerical ring torque; do not substitute a hammer, screwdriver or impact wrench.
10. Restore the tank-top plumbing and canister
Remove temporary caps as each connection is restored. Apply clean engine oil to the quick-coupling tube ends/O-ring contact surfaces as specified for those couplings. Refit the fuel-supply tube and the FTP sensor/tube assembly, including all three connections and its electrical plug. Seat each fitting until it clicks, restore its locking clip/tab and pull-check it.
Refit the molded tank shield and factory insulation. Reconnect and secure the canister; use water-based Ru-Glyde on its rubber vapor-hose interfaces to ease assembly. Keep engine oil off those rubber hose interfaces. Restore every clip and route the fuel/vapor tubes exactly before raising the tank.
11. Refit the tank, covers and driveshaft
Raise the restrained tank enough to reconnect the pump electrical plug and its lock, then position the tank without trapping lines. Refit both support straps, start the fasteners by hand and tighten the rear bolt and front nut to 48 N·m (35 ft-lb). Remove the support only after the tank is securely retained.
Reconnect the filter outlet, chassis vapor connection, filler vapor line and vent-valve hose. Pull-check the quick couplings and restore their locks. Fully seat the filler-pipe hose and position its clamp correctly; tighten to 3 N·m (27 in-lb). Refit the filter shield nuts to 6 N·m (53 in-lb) and its heat-shield bolts to 20 N·m (15 ft-lb). If fitted, reinstall the tank skid plate’s four bolts and nut to 40 N·m (30 ft-lb).
Remove external transmission protection and restore the driveshaft’s original spline and flange alignment marks, protecting the extension seal as the yoke enters. Seat the rear flange squarely on its pilot. Install four new flange bolts and tighten evenly in a star pattern to 112 N·m (83 ft-lb), applying the parking brake as needed to hold the rear driveline. Confirm all attachments and clearances. Any lost transmission fluid must be addressed before the vehicle runs.
12. Refill, restore power and check before starting
With the shaft and tank fully installed, select Park, set the parking brake and lower the vehicle. Refill with clean gasoline using approved equipment, adding enough to cover the pickup; secure the fuel cap. With ignition off, reconnect the IFS switch, then reconnect the negative cable and tighten its clamp to 7 N·m (62 in-lb). If the CD6 audio unit is fitted, keep battery power uninterrupted for at least 30 seconds after reconnecting.
With an assistant ready to switch off, turn the key to ON without cranking and wait 3 seconds. More than one key cycle may be needed. Inspect every disturbed liquid-fuel connection and the accessible tank/module area for wetness or abnormal odor before starting. If access requires the lift, use its locked operating position with everyone clear of moving parts.
For a leak, switch OFF, isolate the negative cable and have retained pressure safely released before opening the system again. Correct the fault and repeat the check. Once dry, start normally and recheck at idle and after shutdown. Refit the passenger kick panel, scuff plate and repositioned weatherstrip after the system checks pass.
13. Complete the fuel and vapor-system verification
Confirm a plausible fuel-gauge reading, stable running and resolution of the original complaint. The canister and FTP work also calls for an EVAP leak test and the specified repair-verification drive cycle; have an equipped technician complete them. A dry pressure-side check does not prove vapor tightness. Do not improvise a smoke-pressure connection or repeatedly crank a vehicle that still will not start.
Related video: 2008 Explorer 4.0L V6
HotRod4D shows the related 2008 Ford Explorer 4.0L V6, rather than this Mountaineer example. Its driveway setup and ring-removal method differ: follow the written hoist procedure, correct ring tool, new seal and fastener specifications, retain factory insulation, and complete the written pressure and leak checks.
Common mistakes to avoid
- Ordering by model year alone, especially overlooking the January 2009 pump change or the separate Sport Trac application.
- Starting with no confirmed new tank seal or reusing the four rear driveshaft flange bolts.
- Lowering a fuel-filled tank, stretching its wiring or hoses, or losing the driveshaft’s original alignment marks.
- Hammering the pump retaining ring, discarding factory insulation or forcing an unconfirmed connector.
- Treating a pressure-sensor code as proof of pump failure or skipping the final fuel and vapor-system checks.
Frequently asked questions
Does this part fit every 2009 Mountaineer?
No. The original-equipment catalog changes the module after January 20, 2009. Check the build date, VIN and original part number before ordering.
Is the 4.0L engine a V6 or V8?
It is the 4.0L SOHC V6. Some listing fields mislabel it as V8; Ford’s engine identification establishes the correct description. The separate 4.6L application is a V8.
Do I need to buy another seal?
You need one new correct seal for the opened tank. Inspect the actual package because the listing and manufacturer gasket descriptions differ. Use a suitable supplied seal only after confirming it; otherwise obtain the VIN-matched 4L3Z-9276-AA seal. Never reuse or stack the old seal.
Can I apply these steps to an AWD Mountaineer or a Sport Trac?
Use the exact procedure for that drivetrain and body. The worked example requires the original one-piece RWD shaft and the stated 4.0L configuration. A part appearing in the compatibility table does not establish identical access or fasteners.
What if my 2008 vehicle has a capless filler?
The later filler uses different draining preparation and the correct refueling adapter. It may still use this pump, but the draining steps here cover only the early removable-cap vehicle. Confirm the build and use the matching service procedure.
Will the module fix an erratic fuel gauge or a pressure code?
It contains a sender and float, but wiring, gauge and pressure-sensor faults need separate diagnosis. Confirm the actual cause before replacement and have the original complaint checked after installation.
Sources and further reading
The written repair uses the stated 2008 Mountaineer RWD 4.0L service information. Product application and production-date catalogs answer separate fitment questions; they do not establish the same repair procedure for every listed vehicle.
- A-Premium FP0079 specifications and vehicle applications
- Ford catalog: 2008 Mountaineer module, new seal and retaining ring
- Ford parts catalog: early removable-cap and later capless 2008 filler
- Ford catalog: 2008 Mountaineer rear driveshaft and flange bolts
- Ford engine identification: 4.0L SOHC V6 and 4.6L V8
- Ford service information: 2008 Mountaineer RWD 4.0L tank removal and installation
- Ford service information: exact pump module, new seal and ring-locking procedure
- Ford service information: two-stage tank draining and special equipment
- Ford service information: IFS pressure relief and pre-start pressurization
- Ford service information: negative battery clamp and reconnection
- Ford service information: one-piece RWD driveshaft removal
- Ford service information: driveshaft indexing and installation
- Ford service information: canister mounting, vapor hose and EVAP checks
- Ford service information: separate fuel-tank-pressure sensor and tubing
- Ford service information: fuel and vapor quick couplings
- Ford service information: hoist contact points and precautions
- Ford service information: 2008 4.0L fuel-pressure specification
- Ford diagnostic chart: P0191 and its possible causes
- HotRod4D: related 2008 Explorer 4.0L V6 repair video