No power at fuel pump/car wont start?

Tiny
JAIYEDEANNE
  • MEMBER
  • 2007 MAZDA 3
  • 2.0L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 190,300 MILES
Not getting power at fuel pump. Cant seem to find relay, only a mini fuse for fuel. Is there a wiring diagram or can you tell me where an actual relay for fuel pump might be?
Saturday, January 3rd, 2026 AT 7:23 AM

4 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,429 POSTS
So the fuel pump will not kick on if the PCM sees no movement in the intake air of the engine MAF/MAP sensors, (this car has both) If you unplug them and the engine starts you know one of these sensors is bad. The PCM will substitute default values allow the engine to start with the sensors disconnected. The fuel pump fuse and control relay is in the fuse box under the hood, left rear of the engine compartment. Here are all of the vital fuses and relays so you can check them out to see if any are blown. Check out the images (below). Let us know what you find.
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Saturday, January 3rd, 2026 AT 10:07 AM
Tiny
JAIYEDEANNE
  • MEMBER
  • 3 POSTS
So I swapped a relay and then disconnected the sensor that is on the air intake after the air filter but before the engine, I believe that’s the mass airflow sensor and I got it to start. It starts for about a few seconds and then it shuts off and I definitely have fuel now coming to the rail and the pump is working. If that sensor is the one that is bad, is it typical for it to start and then shut off after a few seconds?
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Saturday, January 3rd, 2026 AT 1:54 PM
Tiny
JAIYEDEANNE
  • MEMBER
  • 3 POSTS
***UPDATE*** I cleaned the Mass Airflow Sensor & found that a screw was stripped on it. After cleaning, my car now starts & runs. Yay! Idle was rough & high at first but has now evened out. Will be replacing sensor soon as the O-ring on sensor itself is loose & worn. But very relieved to have car start & drive after being parked for 7yrs outside, exposed to all elements. Thank you!
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Sunday, January 4th, 2026 AT 6:25 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,429 POSTS
Glad you could get it fixed, thanks for letting us know. Please use 2CarPros anytime we are here to help.
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Sunday, January 4th, 2026 AT 9:06 AM

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