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350matt
350matt, Engineer
Category: Mazda
Satisfied Customers: 21975
Experience:  Mechanical Engineer BEng Hons22 years experience
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2005 mazda miata mx 5. fuel pump doesnt have 12 volts going

Customer Question

2005 mazda miata mx 5. fuel pump doesnt have 12 volts going to it. The fuel pump relay isn't coming in, removed the relay tested and its working. car will not start
JA: How many miles are on the car? Has the car been starting normally?
Customer: bout 150,000. It started fine.. My sister said she cranked it then it started running bad so she shut it off and it hasn't cranked since. I'm suspecting the cam shaft position sensor but im not 100% sure.
JA: Are you fixing your Miata yourself? What have you tried so far?
Customer: fuel pump relay isn't coming in. I pulled it off and tested it with a battery and an ohm meter and it's working properly
JA: Anything else you want the mechanic to know before I connect you?
Customer: don't think so
Submitted: 2 months ago.
Category: Mazda
Expert:  350matt replied 1 month ago.

Hello

if the fuel pump relay isn't being energised I'd next check to see if you're getting 12V on the ECU fuse with the ignition on.

as the ECU sends the switch signal to the pump relay

also have you checked the voltage in the pump relay sockets? as there should be a live feed that is switched by the relay down to the pump and the switching feed should flick on briefly when you 1st turn the key

if this is all OK then I'd say to run a fresh wire from the relay directly to the pump as there must be a break in the wire somewhere and its easier to run a new wire and the cut the old wire at both ends to avoid any issues with shorting out