Hello everyone!
I am experiencing vapor lock with my car (or at least i assume)... I only experience it when trying to start the car after it has heated up. It takes about 5 mins after the engine is shut off for this to happen. Once the car cools then it will start. I have some theoretical knowledge but no experience so i want to check my theory with other owners (you).

I believe the issue to be a problem with fuel pressure being maintained after the vehicle is shut off, if the fuel pressure drops, then the boiling point of gasoline drops and this allows the fuel in the injectors to boil. I don't have a pressure gauge to check this theory, however when you turn the car on, you have to wait for the fuel pump to shut off before starting the car. The car runs almost flawlessly, it only shows minor hesitations during cruising, like the power loss when turning on the a/c. The car still accelerates great. Also the car is running rich.

This leads me to believe that the fuel injectors are leaking a little. But fuel injectors are expensive, anywhere from $30 for remanufactured to $180 for new a new one.

An experiment to test my theory is to turn the car on and let the fuel pump build up pressure, then clamp off the output and return fuel lines at the fuel tank and let the car sit. If the pressure drops on the fuel lines then I have a leak somewhere. I could repeat the experiment and isolate different parts of the fuel line to find the leak.

Please let me know if my theory is sound, or if there are any other possible reasons to the problem.

Thanks

P.s. I am new to the forum

 

Welcome to ZDriver.

These cars very seldom have vapor lock problems. There are simple tests you can do to find this prob.

#1... Test fuel pressure. It should be between 30-35psi at idle.

#2... Pull the spark plugs after it has sat for a few minutes & look at the tips... if they are wet... leaky injector. You can also compare tips to make sure all cylinders are running equally.

#3... If it's a non-turbo, check your cold start valve.

#4... Check the air regular.

#5... Check the other sensors: AFM, CHTS.

Also check timing. And buy a Haynes manual if you haven't yet.

 

Forgot to mention, but it is a turbo.

The Air Flow Meter has been replaced with a new one. What is a CHTS?

Can you rent a fuel pressure gauge from like autozone or baxters?

I will have to give #2 a try

Does it mean anything that the fuel pump has to shut off before i can start the car?

 

Was that when it started acting up?

Cylinder Head Temp Sensor... very temperamental. If it's not reading correct, it will throw off the a/f ratio.


Usually...


Or else what? The fuel pump always primes the line before starting, then shuts off until you start.

 

The previous owner replaced the airflow meter while trying to hunt down major hesitation issues when accelerating. It turned out that the issue was with the connectors for the air flow meter. After i bought it i started having problems with the motor running rough after a warm start, then it would not start at all. It does not even attempt to start, it just cranks over.

I will research more about the Cylinder Head temp sensor, if you know any direct links to info, that would be greatly appreciated.

As for the fuel pump, does the car not maintain fuel pressure after it has been turned off?

Thanks, this is definitely helping me rethink the problem, i was almost dead certain it was the fuel injectors...

 

It should. If it doesn't, either the fuel pressure regulator (on the fuel rail) or the fuel damper has gone bad.