Powertrain, generic (extended)

P2A90 Alternative Fuel Pump C Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P2A90 marks pump C of the alternative fuel system as delivering too little. A third pump may belong to a further tank or, in Caterpillar's design US10060421B2, be one of several pumping elements driven in sequence. Besides wear, cryogenic pumps have a typical weakness that Caterpillar's patent US9228574B2 describes: if the liquid at the inlet has warmed enough to form vapour, the pump cavitates and delivery stops, so centrifugal designs need a positive feed pressure. Short bursts of poor output after long parking, with warmer LNG in the tank, fit this picture; a permanent shortfall points to worn parts. The pump diagnosis in US20080302111A1 explains how a slow pressure rise reveals the loss. No manufacturer publishes P2A90; P2A87 to P2A8A cover pump C's stroke valve.

Likely causes

Vapour at the inlet of pump C after warm soak, causing cavitation
Worn seals or valves in pump C
Clogged inlet strainer or filter ahead of pump C

Symptoms

  • Warning lamp on
  • Weak pull or hesitation shortly after a long stop
  • Gas pressure recovers slowly after heavy acceleration

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€800–6,000
Time3–10 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

alt fuel pump calt fuel filter

Related codes

P2A8EP2A8FP2A87P2A88

References: law.cornell.edu, patents.google.com, patents.google.com, patents.google.com.