Why doesn't my nissan micra start when it's Hot?

Question

Hi guys i'm a trainee mechanic myself but i'm not sure what is wrong with my mates nissan micra 1996
its a 1000cc standard automatic,the situation here is indefinite the car starts in one shot when its cold however if i switched off the ignition as it warms up and try again it doesn't start the motor just spins the engine,
it happens most of the time unless the vehicle was kept until ts cold enough to start ,

the o2 sensors seems to be replaced and new,throttle bodies are ok,plugs are fine ?
any ideas .

Well the temperature doesn't have to go beyond 90 degrees when this happens

Answer 1

Hi Shehan. My Micra did the same thing last July, when the engine was hot and especially during the hot weather we had in the UK. The problem ended up being the air flow meter just under the carb / pump. When I disconnected the electrical connector from the meter the car started every time. Only problem was the engine ran uneven and the orange management dash light came on. Nissan told me the unit could not be split and the whole pump was £500. So I got an air flow meter at world car parts. com for £65 delivered. The allen screws were security type jobs and needed a set of special allen keys £10. I replaced the meter in 2 minutes and the light went out. The engine ran uneven for about 1/2 hour drive and cut out a few times, but then it settled and now starts and runs ok (touch wood)

Hope this helps.

Answer 2

Sounds like it is a vapor lock, excess heat causes the fuel to heat up to the point where it vaporizes in the carburetor, fuel pump or fuel lines. This fuel vaporization keeps fuel from reaching the engine and prevents your vehicle from running and it wont starts untill its getting cool.

Answer 3

Hi so time to get a motor engineer with a lot more knowledge to fix this then.