Is there supposed to be constant fuel pressure?

[fowljesse]

Even when the car isn't running? I thought that the pressure was not supposed to stop, ever. I disconnected my fuel pump, and tried to start the car, to relieve the pressure, but it won't start, meaning there is no pressure. This would help diagnose the problem I've been having, IF there's supposed to be pressure. The last time the car ran was yesterday.

[ninjajim4]

if you disconnnected the pump, isn't that releasing all the pressure in the lines? you need a complete circuit. or do you mean you just disconnected the power?

[MX3ak]

On a running engine, if you disconnect vaccum line's fuel pressure it's like the intake is WOT and it will deliver the maximum fuel.

Dunno if it matters but TPS also has a role on Fuel management.

[fowljesse]

I just know that when i replaced the fuel filter, I forgot to release the pressure. It hadn't run in a few hours, and it besquirted me with a wrath. When I did my Mercedes a long time ago, I got what felt like a gallon shower. When I replaced the FPR just now, there was no pressure.

[hgallegos915]

yeah the fuel system is pressurized.


If you are wanting to release the pressure. simply remove the relay for the fuel pump or the ENG fuse and crank a bit. That releases all fuel pressure.

[fowljesse]

That's why I was concerned.. Mine doesn't have pressure. I can pull out the FPR without pulling the pump wires. I guess I have to go through the entire system to find a leak

[Slammed6]

The way mazda developed the fuel system on these cars along with the MX-6 and Probe is the fuel pump does not start pressurizing until the distributor senses the motor is turning. This is a safety feature so if you were to crash and the motor dies but your key is still in the on possition your car is not spraying fuel all over the place.

To test the fuel pressure with the motor not running you need to open your diagnoses box and jump the pin for the pump and B+ or gorund i can't remember off the top of my head, Try the ground first and if nothing happens tap it on the B+. You will hear the pump kick on and your in business, test the pressure.

[fowljesse]

Coool. Thanks! That's what i needed to know. There's pressure when I start it. Everything's AOK.