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Old 08-24-2013, 05:03 PM   #1
MeanMachine
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Default Vapour Lock

Can someone enlighten me about vapour lock, I drove to the dealership to find some exhaust tips the other day and parked the car for 5 minutes and then re tried to start the car the engine is turning i.e. wont fire.

Got the mechanics to help me push the car inside the workshop on a thursday and they started the car on saturday morning and it worked properly.

The manager told me its vapour lock and it happens sometimes, its the first time I have the car "not start" at hot conditions. I have changed my Turbo Control Unit, injectors last may. The car has been trouble free except this one incident. I picked up the car drove it for +30 minutes, picked up a friend for coffee and sat for another 30 minutes and the car started with no problems.
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Old 08-24-2013, 05:12 PM   #2
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Vapor lock occurs when fuel vaporizes in the fuel line due to high heat.
The fuel system is designed to hold a nominal amount of residual pressure on the system to prevent vapor lock and also so when you hit the key, the car fires immediately.
The usual culprit in a vapor lock condition is the accumulator, which a spring loaded diaphram that keeps the pressure up. Your mechanic can test the system and watch the pressure decay. Minimum value is 1.4 bar after 20 minutes. Good luck.
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Old 08-24-2013, 05:16 PM   #3
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Quote:
Originally Posted by Metal Guru View Post
Vapor lock occurs when fuel vaporizes in the fuel line due to high heat.
The fuel system is designed to hold a nominal amount of residual pressure on the system to prevent vapor lock and also so when you hit the key, the car fires immediately.
The usual culprit in a vapor lock condition is the accumulator, which a spring loaded diaphram that keeps the pressure up. Your mechanic can test the system and watch the pressure decay. Minimum value is 1.4 bar after 20 minutes. Good luck.
The accumulator is also replaced last may, thanks for the info your very helpful as always.
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Old 08-25-2013, 02:58 PM   #4
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Do you have ethanol in your fuel?
Use this hot starting procedure:
Turn ignition on and let pumps run
push throttle to the floor and hold while cranking
release throttle when it catches.
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Old 08-25-2013, 03:31 PM   #5
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Originally Posted by rstarga View Post
Do you have ethanol in your fuel?
Use this hot starting procedure:
Turn ignition on and let pumps run
push throttle to the floor and hold while cranking
release throttle when it catches.
I drove the car and it runs great, it was just that one incident and after that no problem.

No ethanol, just normal 98 octane pump gas
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Old 08-25-2013, 03:38 PM   #6
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In this part of the world 10% ethanol is used to raise the octane rating of 98 (ron + mon) gas and it's not specifically noted at the gas station. You may check to see if this is being done in your region.
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Old 08-26-2013, 09:58 PM   #7
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He is in Kuwait so I doubt it, although they most likely import their fuel, so who knows where it comes from. The heat must be a big factor too.
An aircooled Turbo in that heat is the worst of all worlds. I certainly would not raise the boost under those conditions.
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Old 08-27-2013, 07:10 PM   #8
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Quote:
Originally Posted by rstarga View Post
He is in Kuwait so I doubt it, although they most likely import their fuel, so who knows where it comes from. The heat must be a big factor too.
An aircooled Turbo in that heat is the worst of all worlds. I certainly would not raise the boost under those conditions.
We produce fuel and export it vice versa

I drove it today for 45 minutes no problem.
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Old 08-27-2013, 08:49 PM   #9
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Not always. but vapour lock normally occurs when the tank is below 1/2 full, it is hot outside, the engine is hot, (not necessarily overheated), and you stop to grab a coffee at Starbucks, (example). The car heat soaks for 10 or 15 minutes, then you go out and try to restart.
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Old 08-27-2013, 09:01 PM   #10
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It occurred when the tank is 1/4, makes sense I drove it to the dealership stopped to check parts for oem exhaust tips and re started which it didnt.
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Old 08-28-2013, 09:01 AM   #11
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All manufacturers do hot weather testing to find these problems. There are tests that cover heat soak that are very extreme. I still recommend a check of residual pressure. Something is not right.

Last edited by Metal Guru; 08-28-2013 at 10:26 AM.
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Old 10-31-2013, 06:47 PM   #12
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Took my car where its been repainted, anyways they solved the issue. When the car was on the jack they started it and closed it it didnt start. So its not an issue of vapour lock but electrical, they changed the relay for the fuel pump.

When they tried starting it the fuel pump wont work, so now the issue is resolved than you. I will test it out after PSS10 suspension installed.
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Old 10-31-2013, 06:47 PM
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