MA93
MA014 Mazda Reference
Subject: Fuel system pressure testing for fuel injected engines
Symptom: Hard starting cold, power loss climbing hills, overall poor
performance, engine surges and then stops running
Source: Mazda service manuals and technicians
Risk of fire.
• Wear safety goggles and protective clothing, user and bystander.
• Relieve fuel system pressure before opening lines and connections.
• Keep cigarettes, sparks, open flame, and other sources of ignition away from
vehicle.
• Keep food out of area when fuel is present.
• Disconnect the battery ground before opening any fuel system fittings, reconnect
the cable to run the engine or operate the fuel pump for testing.
• Gasoline, methanol and oxygenated fuels are toxic and flammable and must be
handled appropriately.
• Keep a dry chemical (Class B) fire extinguisher rated for gasoline, chemical, and
electrical fires in the work area.
Fire can cause serious injury.
IMPORTANT:
The fuel system remains under pressure when the engine is not running. Release fuel
pressure before disconnecting any fuel line to reduce the chance of personal injury or fire
damage to vehicle components.
IMPORTANT:
Strict observance of posted speed limits and attention to driving conditions are mandatory
when conducting fuel pressure testing while road testing.
IMPORTANT:
Late model fuel lines use plastic snap-lock connections that are easily damaged. The fuel line
must be replaced if the snap-lock connection is damaged when it is disassembled to install a
fuel pressure gauge. The sealing O-rings should be replaced whenever a connection is
opened.
NOTE:
i Operating with a low fuel level may overheat the electric fuel pump. Mazda advises that low
fuel level in the tank may damage the fuel pump.
The ECM-PCM controls ground to the fuel pump through a relay.
RX-7 models with fuel injection use a dual primary-secondary injection system controlled by
the ECM. Each injection pipe has two injectors. These systems use an electric in-tank fuel
pump.
