Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

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Fuel Pump Electrical Circuit

When ignition is first turned to the On position, without engine running, the ECM turns the fuel pump relay On for 2 to 3 seconds. This builds up fuel pressure quickly. If engine is not started within two seconds, the ECM shuts the fuel pump Off and waits until ignition reference pulses are present. As soon as engine is cranked, the ECM turns the relay On which powers the fuel pump.