P2636
Fuel Pump B Low Flow/Performance
The second fuel pump runs but does not deliver expected volume or pressure. Worn pump, restricted filter, or leaking pressure regulator.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Symptoms
- Check engine light on
- Hard start, no start, or stalling under load
- Power loss especially at high load or rpm
- Possible long cranking time
Common causes
Ordered by how often each turns out to be the cause.
- Worn impeller reduces volumetric efficiencyCommon
- Restricted in-tank or in-line fuel filterPossible
- Pressure regulator leaks back to tankPossible
Parts involved
- Fuel Pump B
- Fuel Filter
- Fuel Pressure Regulator
P2636 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.