Ok, so as some of you may know I just moved up from a 12a car to my new -SE and Im just getting into the new systems associated with it.
Other than a few minor issues my car seems to be running great. Just wanted to do the once over on it so Ive been checking the standard things...When I went to plug in my TPS tester I noticed that this little plug was tucked under the airbox with a piece of metal jumping across the two terminals.



Could someone please tell me what this plug is for, and why the jumper may be in it if they know? Im a little bit worried to remove it until I have some idea what it may be doing. Thanks!

 

Fuel pump shortcircuit terminal. Shorting it as pictured means the fuel pump comes on whenever the ignition switch is in the on position regardless if the car is running or not. May have been shorted by the po to mask an issue with the fuel system.

 

PT Ray is dead-on.

This jumper is normally used by mechanics to test fuel injector replacement, fuel rail replacement, and fuel pressure regulator replacement to ensure that there aren't any leaks before installing the Upper Intake Manifold (UIM) and then finding out that there's a leak to fix. The jumper should only be 'jumped' for the test, i.e, ignition to ON, and you should hear the fuel pump run - if you're looking at the fuel rail, you'll also be able to 'feel' the fuel flowing to the injectors to look for leaks. In other words, this allows the fuel pump to run high pressure to the rail WITHOUT the engine running, which is obviously not possible unless the UIM is installed first.

It's a bad idea to have this 'jumped' all the time; the fuel rail will see 37-45psi even thoug the engine isn't turning, and could lead to fuel bypass of an open injector, allowing for leak-down into the intake runners and a flooded engine. Mazda designed it this way so that the rail would only see pressure with the engine TURNING, i.e., air flowing through the AFM, which vastly prevents flooding the engine.

Some suggestions to troubleshooting this;

1) unplug the jumper
2) attempt to start the car as normal
IF the car doesn't start, you probably don't have fuel, in which case, you'll need to start looking at the fuel pump electrical (maybe a bad AFM) to find out why it's not getting power when the engine is starting.

Reply back here if that's the case and I'm sure you'll get some great replies. HTH,

 

Thanks guys, I really wondered if thats what it was, as I noticed the pump running with the ignition and made another post about it. I had the feeling I should have put this picture and question in the other thread as well, but I decided not to. Oh well. Thanks a lot!!!!