Fuel Pressure (Fuel Injection): Notes

WARNING: ALWAYS relieve fuel pressure before disconnecting any fuel injection related component. DO NOT allow fuel to contact engine or electrical components.

On RX7, disconnect fuel pump connector at shock tower in trunk. On all others, disconnect circuit opening relay located behind left kick panel on B2600i, and 929. On 323 and Protege, disconnect circuit opening relay located on passenger side wall near ECU. On MX-6 and 626, located on fuse block. On Miata, disconnect circuit opening relay located under dash left of steering column. On MPV, disconnect circuit opening relay. The relay is mounted on ECU, under protective cover on passenger side floor. To bleed down fuel in system, start engine (if possible) and allow to die. Connect pressure gauge to fuel line at fuel filter. Reconnect circuit opening relay.
Turn ignition on. Using a jumper wire, connect terminals of Yellow fuel pump check connector together. Fuel pump check connector is located on firewall, near windshield wiper motor on B2600i, MX-6, 323 and 626, and near airflow sensor on MPV, RX7 and 929. On Miata, jumper test connector terminals Fp and ground. If pump runs, check fuel pump circuit and circuit opening relay (and fuel pump resistor on RX7).
If possible, start engine. Check fuel pressure with vacuum connected to and disconnected from pressure regulator. Turn engine off and disconnect jumper wire at fuel pump check connector. Wait 10 minutes and ensure residual pressure is at least 21 psi (1.5 kg/cm² ).
Operate fuel pump by jumpering fuel pump test connector. Check fuel pump performance. Pinch hose between pressure gauge and fuel filter. Do not hold longer than necessary to check pressure. See FUEL PUMP PERFORMANCE table. If pump does not meet specifications, check fuel pump circuits, fuel pump, fuel tank, fuel filter or replace fuel pump.