P5 cranks no fuel

I have a 2003 protege 5 that was rough idling for a couple months sometimes it would even shut off on me. A couple times I would turn the ignition to the on position and would completely loose power no light in the dash or radio nothing. Eventually the symptom happened while driving, going about 45mph the car shut off power on me my speedometer went to 0 and after a couple seconds power came back car was still on even, two days after that on the highway going about 80mph the car shut off on me power came back but engine was off I pulled over and car would crank but wont start, originally i assumed it was the fuel pump because I didnt hear it prime so I bought one and replaced it, new pump wouldnt prime either we checked the pumps with a battery and they both work however they will not prime on the car, I replaced the relay and it still does not get power additionally my OBD2 no longer works it wont even read that its hooked up to the car, I saw a YouTube video where a guy jumped his relay and has been using a switch on his pump, but I would like to see if you guys can help with this, my friend is leaning toward the ECU because of the electrical issues and the fact that OBD2 doesnt scan what do you guys think?
 
V
2010 Mazda 5 Sport
Definitely an electrical issue.

To me, when you get a complete loss of power, that reeks of bad battery cables and a battery cable ground.

I'm guessing why the ECU won't read is because it has little or no power.

Does your OBDII scanner work in other cars?
 
Yes I tried three scanners none pick it up and battery terminals are good getting power and tight. The scanners work on other cars
 
Yes I tried three scanners none pick it up and battery terminals are good getting power and tight. The scanners work on other cars. I did notice that the port on my negative terminal is flimsy like a weak metal
 

pcb

The Diagram Dude
V
2002 mazda protege 5
I'm thinking of a bad ignition switch.

They wear out over time and stop making contact.

They've gone bad for a bunch of us here on the forum.

 

pcb

The Diagram Dude
V
2002 mazda protege 5
A bad ignition switch could have popped your engine fuse as well.

I'm pretty sure if the engine fuse is blown it turns off the ECU and disables the OBD2 port.
 

pcb

The Diagram Dude
V
2002 mazda protege 5
Yes, indirectly.

The switch sends power to the ECU.
If the ECU is happy it'll allow the fuel pump to turn on.

The signal controlling the fuel pump relay comes from the ECU. Conditions have to be met before the ECU will send power to the fuel pump relay.
 

pcb

The Diagram Dude
V
2002 mazda protege 5
Check that fuse. If it's blown, replacing it might enable your OBD2 port.
 

pcb

The Diagram Dude
V
2002 mazda protege 5
Here's the info about replacing and inspecting the ignition switch.



Testing the switch can be misleading because you've probably got an intermittent failure.


Here's a link to the factory service manual.

http://www.floptical.net/mazda/
 

pcb

The Diagram Dude
V
2002 mazda protege 5
I'm thinkin the ECU isn't happy and won't allow the fuel pump to turn on.

You mentioned that your dashboard went black and the car died.

If you have a bad connection on one of the contacts inside the ignition switch then power may not get to the ECU.



You could test for power at the ECU on the appropriate pins to see if it's getting through the ignition switch but if it were me, I'd just throw the $30 at the car and see if that makes it happy.

You could have some sort of major short or open in your wiring somewhere that can be really hard to trace and find.


An open circuit (no connection) in the ignition switch would be the same as turning your car off when you're driving.
 

pcb

The Diagram Dude
V
2002 mazda protege 5
The ECU also kills the ignition if it's upset, so you can test for Spark by removing a spark plug plugging it back into the boot and laying across the valve cover to see if it Sparks.

The starting system is separate and you can still crank the engine when the ECU has shut things down.
 
So if you guys read above, I thought the negative terminal on battery was weak, well I de order to change it today for the hell of it and it had a pretty good crack that*s why it was weak, replaced it and now the car starts, let*s hope this was the issue, I did not replace the ignition switch but since I*m still skeptical at the electrical issues I was having I*m just going to keep it just Incase thank you all for your help!!!
 

pcb

The Diagram Dude
V
2002 mazda protege 5
I'm glad you figured it out

Our factory battery connectors are straps not lugs.

I've got new lugs to put on my car but so far my straps are still working.

I'm going to put off the conversion until my car craps out.

 

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