A Kenworth that won’t make power isn’t a truck. It’s a parked invoice. When an MX-13 starts logging rail pressure codes, falling on its face on grades or cranking forever on cold mornings, suspect the unit pumps.
The PACCAR MX-13 charges its common rail with cam-driven unit pumps built by Delphi. Delphi calls the design F2P, and the Delphi base code on the tag usually starts with BEBU2C. It lives in Kenworth and Peterbilt highway tractors and vocational trucks, and listings show the same numbers for the MX-11.
Identification, appropriate bench testing and a clear repair recommendation can help determine how to put that truck back to earning.
Also Known As
Nobody at the fuel island calls it an F2P. These names all point to the same part:
- PACCAR MX-13 unit pump, MX-13 fuel pump, MX-13 high-pressure pump
- Delphi F2P or F2P series pump
- BEBU2C and BEBU4B (Delphi base codes)
- Fuel pump unit (common on parts sites)
- PHINIA F2P, since PHINIA now owns the Delphi brand
Did You Know? PACCAR bought DAF Trucks of the Netherlands in 1996. The MX-13 grew out of DAF’s MX engine and came to North America in 2010, built in Columbus, Mississippi.
How the MX-13 Unit Pump Works
Picture the common rail as a water tower, the unit pumps as the crew keeping it full and the injectors as faucets the computer opens on command.
- A low-pressure pump pulls fuel from the tank through the filters and feeds the unit pumps.
- Each unit pump sits in the block and rides a camshaft lobe through a roller tappet. Every time the lobe comes around, the plunger gets shoved up its bore.
- Inlet metering controls how much fuel each stroke takes, which is how the computer holds rail pressure.
- The pressurized fuel goes into the rail, and the rail feeds each injector on command.
Shop Talk: A unit pump is one pumping element in its own housing, driven by the engine camshaft. On the MX-13 it charges a rail. On pump-line-nozzle engines each one feeds a single injector, as on our PLD unit pump page.
What It Fits
| Make and model | Engine | Years | Notes |
|---|---|---|---|
| Kenworth T680, T880 | PACCAR MX-13 | Highway and vocational | |
| Kenworth T660, T800, W900 | PACCAR MX-13 | Option on some builds | |
| Peterbilt 579, 567 | PACCAR MX-13 | Highway and vocational | |
| Peterbilt 587, 389, 386 | PACCAR MX-13 | Option on some builds | |
| Kenworth and Peterbilt regional and vocational models | PACCAR MX-11 | Confirm the pump number before shipping |
Part Numbers We See
Owners search by PACCAR number, and parts counters add suffixes. PE, PEX and PRX mark different supply versions of one part.
| PACCAR number | Suffixes seen | Delphi cross-reference | Notes |
|---|---|---|---|
| 1934322 | PE, PEX, PRX | EX551001 | Listed for MX-13 and MX-11 |
| 2034927 | PEX, PRX | EX551001 | Same Delphi reman family |
| 2102391 | PEX, PRX | EX551001 | Seen alongside 1934322 |
| 1871117 | None seen | EX551001 | Listed as an OE cross-reference |
| 1861200 | PEX, PRX | Listed as an EPA10 MX-13 pump |
Delphi’s own base codes are BEBU2C00000, BEBU2C00300, BEBU2C00500 and BEBU4B00200.
Owner’s Tip: Before the pump comes off, photograph its label and the engine serial plate and send both with your order. Ten seconds with a phone can save a day of phone tag.
Why MX-13 Unit Pumps Fail and the Symptoms
Most failures trace back to what the pumps are fed.
- Dirty or wet fuel. Grit and water, often let through by stretched filter intervals, score plungers until they can’t hold pressure.
- DEF in the fuel tank. One wrong nozzle. DEF corrodes fuel parts and leaves crystals behind.
- Air on the supply side. A loose fitting or tired low-pressure pump starves the unit pumps.
- Tappet and cam wear. The roller takes a hit every revolution.
Symptoms to watch for:
- Low power or a derate, especially on grades
- Long cranking or hard starting, worse in the cold
- Rail pressure codes, low or out of range
- Rough running, surging or stalling
- A rising oil level
Bench Notes: A worn pump rarely fails alone. Debris from a scored plunger can ride the rail to the injectors, so our report tells you if the rest of the system deserves a look.
What We Do to Your MX-13 Unit Pump
| Service option | Typical evaluation or service scope |
|---|---|
| Test and report | Bench test, inspection, written report with photos and a service recommendation |
| Rebuild and calibrate | Teardown, cleaning, new wear parts and seals, calibration, final bench test and test sheet |
| Exchange (when available) | Ask whether a compatible exchange unit is available and how the core process works |
Running a yard full of Kenworths and Peterbilts? Share your fleet application and component identification for service planning.
What Model-Specific Verification Can Document
Evidence for PACCAR MX-13 Unit: When an approved procedure exists for this exact component, useful documentation can distinguish identification, visible condition, observed wear or contamination and supported functional test results. Record the assembly number and available engine data before deciding which checks will answer the reported complaint. Bench findings cannot replace the engine-side diagnosis. See how pump testing is evaluated.
Repair Options and Technical Considerations
For PACCAR MX-13 Unit, the available path follows what inspection actually finds—not a universal rebuild recipe. DCT reviews the component design, exact assembly number, contamination history and the applicable test procedure, whether the correct service parts and calibration information are available, and which work the customer chooses to authorize. Any exchange option is confirmed for the exact part rather than assumed from the family name. Explore how repair options are compared.
The service path depends on plunger and tappet wear, contamination findings and parts availability. Read how core returns and warranty work and what a complete rebuild involves.
How to Ship Your MX-13 Unit Pump
- Start your order online or request a repair evaluation with the PACCAR number, engine serial and symptoms.
- Write down any fault codes, or include a screenshot from your scan tool.
- Follow authorized de-fueling instructions and protect the ports with clean, suitable caps.
- Use the approved inner containment and cushion the pump sufficiently to prevent movement in transit.
- Put the completed intake details and a return-contact method inside the box.
- Ship to the address provided in your service instructions with tracking.
Ship It Right: Never ship a pump with open ports or tape over the fittings. Tape glue and cardboard dust are exactly the kind of dirt a precision pump hates.
Related Pumps and Parts
- Delphi, Lucas and CAV pumps
- Detroit DD13, DD15 and DD16 high-pressure pump
- Mercedes MBE and Mack E7 unit pumps
- Injector repair
- How bench testing works
FAQ
Is the Delphi F2P the same as the MX-13 fuel pump?
Usually, yes. Owners who say MX-13 fuel pump almost always mean the Delphi F2P that charges the rail. The low-pressure supply pump is a separate part.
Should I send one unit pump or all of them?
Send the one that tested bad, at minimum. If contamination caused the failure, the others drank the same fuel, and testing them together saves a second round of downtime.
Will a rebuilt pump clear my derate?
Only if the pump caused it. Rail pressure codes can also come from filters, the supply side, sensors or wiring. Our report tells you whether the pump was the problem.
Do you offer fleet service planning?
Request a repair evaluation with your truck count. Ask about intake arrangements for multiple units and the available service options.
Your MX-13 was built to pull. Let’s get it pulling again. Start a Mail-In Repair or request a repair evaluation.