Car will not start / idle

starting
stall
mazda
protege
starters

#1

My 1998 Mazda Protege LX, with about 81K miles on it, gives me starting trouble. It wont turnover and idle unless I put press the gas pedal. In fact it stalls if I dont hold down the gas for couple of minutes. It will start though if I press the gas way down, but I dont like doing that because it starts smelling of gasoline. This happened on cold and rainy days a lot but now that its warmed up here in the northeast, the problem still persists and makes me more worried.



I know fuel filter and pump are fine because I got it checked in the winter. The spark plugs are about 20,000 miles old, and air filter ~5000 miles. What else do I need to check ?


#2

[b]The hard starting might be caused by a leaking fuel pressure regulator.

When this happens, fuel is allowed to enter the engine as it sits via the vacuum hose between the regulator and intake manifold. The when you go to start the engine cold, not only is there fuel sitting in the engine, but the injectors are also adding fuel. And this can lead to a gas smell.

When you step on the gas while starting the engine cold, you’re telling the computer that the engine is flooded. The computer then cuts the injector pulse widths in half in order clear out the flooded condition.

Once the engine starts, it runs rough until the excess fuel is burned off. And then the engine runs normally.

Tester[/b]


#3

thanks Tester, I was wondering though, if there is fuel sitting there already why do I need to apply extra gas to get it started, and also why do I have to hold it down to prevent it from stalling. After a couple of minutes of holding down , it idles on its own but really weakly (~500 rpm). on a normal start it would be 1000-1500 rpm)


#4

[b]When you apply the gas pedal it does two things. It tells the computer the engine flooded, so the computer puts less gas into the engine. And it also allows more air into the engine because the throttle plate is open. This all helps in getting in getting a flooded engine started.

The reason you have stay on the gas once the engine starts is, all the excess fuel is still there, while at the same time the injectors are introducing fuel. So in order to keep the engine running you have to stay on the gas to allow more air into the engine to burn this rich mixture. Once the excess fuel is burned off, the engine runs normally.

But have someone check to make sure that the fuel pressure regulator isn’t leaking. Because this is one of the symtoms when one does.

Tester[/b]


#5

Will do. Thanks for your suggestion and explanation.


#6

Also, if this leakage is happening, is it easy to detect from outside (gas under parked car) ?


#7

Well Gollee,
wonder if they used a rubber timing belt
on that model… Hummm


#8

yes they have a rubber timing belt, why ?