Hot start problem... and before you all groan and put your fist through the monitor , read on.

My car obviously has the problem. I have a fuel cut switch to overcome this. Here is what I do.
I have been killing the engine by using the fuel cut switch. After a few seconds the engine dies, obviously from a lack of fuel. I leave the fuel cut off (no fuel), and take the key out.
Now, I come back 20 minutes later, put the key in, start her up, it does, but the engine will die if I don't flick the fuel cut switch (obviously because there is no fuel flowing).

My question... how is the engine firing up, when there is no fuel flowing, and the engine was shutdown by starving it of fuel, so there should be minimal, if any, fuel in the engine. Where is the fuel coming from?!
By the way, I had all four injectors replaced with NEW mazda ones a year ago.
Now I know the fuel system is pressurised, but that would only be, if there was NO fuel cut switch engaged.

I just don't understand.

 

odd...

 

Neither do we!

 

magic.

 

how do you have the switch wired in?

mike

 

Vapours in the engine, intake and fuel rail.

 

I'm using the middle wire on the 5 wire connector under the steering column (black and yellow wire, if I remember correctly) under the steering column.

 

Vapours I can understand, but the engine will run for about 5 seconds before it dies (without flicking the fuel cut switch). That's a long time for it to run on vapors.

 

Aaron is right, if you've ever pulled power to the fuel pump and tried to start it, forgetting that there is no power to the pump, it will still try. Hell, I have started it like that twice before. It'll go. Thats pretty normal. Also... gravity COULD pull fuel out of the injectors that has collected as your vehicle sat.

 

Ok, that makes some sense. So it IS possible. I thought my car was evil or something (well it still is )

 

Vapours? Maybe, but what PSI is the fuel pressure at when it stalls? Even when you kill power to the pump, the engine will stall and you will still have fuel pressure. I think that you are just running on what pressure is left.

Also, doesn't starting the car energize the pump separately vs. fuel pump running with ignition on ? The starting(prime pump) is usually different from the running(continuous on).

You would need to check the wiring(whereyouhookedup) vs. what is energized when car is started or running.

Check your wiring schematic, fuel pump relay, fuel pump harness, and compare to your switch location.

 

Ok, you're starting to talk Greek to me , but I get the general picture. It's not as mysterious as it first sounded.
Thanks.

 

Let's see... you leave you car sitting in the summer heat, and vapours of gasoline form and fill the charcoal canister. Wanna see just how much vapour there is? Leave a plastic Jerry can all sealed up sitting in the sun for 20 mins. Notice how it sweels leg a fat woman? Now triple the size of the jerry can, and put it next to the radiant heat of dual exhaust cans....

Its the fuel vapours.

 

Fuel pressure solenoid working?

 

whats the point of a fuel cut switch?

 

When FC3 injector's get clogged, they fail in the open position, allowing the engine to flood when stopped, making for hard or impossible starts.
The best solution is new or cleaned injectors, but those who don't have the time or the money usually install a fuel cut-off switch, which cuts power to the fuel pump as a method to turn the car off. The pump stops running, and as the fuel rail empties of pressure, the engine stalls. Without the rail pressure, the injectors don;t leak, and you can start your car next time you go to do so.
Sean Cathcart