Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1990 Mazda MX-5 Miata StandardFACTORY OEM SERVICE PROCEDURE
Fuel Pressure (Electrical): Notes
- Turn ignition on. Locate fuel control unit under left side of dash. Using a jumper wire, connect terminals "B" to "D". Fuel pump (located in tank) should operate. If not, check and replace fuel pump, if necessary. Check fuel pump pressure. SeeFUEL PUMP PERFORMANCE
table.NOTE: Fuel pump control unit terminal identification is not available.
- If fuel pump operates, remove jumper wire. With ignition on, backprobe rear of fuel pump control unit. There should be 12 volts on terminals "A" and "D" only. If not, check ignition and power feed.
- Allow engine to idle. There should be 12 volts on terminals "A", "B", "D" and "F" only. If voltage is missing on terminal "B" only, replace fuel pump control unit. If any other terminal did not test as described, check ignition coil (tachometer signal) and power feed.
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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