I am inquiring on behalf of a friend who owns a three-year-old
Toyota Vios J spec.
Recently, on several occasions, he faced a problem whenever
he traveled long distance.
When he stopped at traffic lights, junctions or at the
roadside, he engine revolution (based on rev meter) became
erratic, idled and dropped down to the extent of stalling.
After restarting, the car wouldn't move smoothly but jerked
all the way.
My friend had to stop and give the car a rest for about an
hour or so; then h was able to continue his journey.
After some distance, the problem occurred again.
My friend thought that it was not engine overheating as the
temperature gauge looked normal.
He already sent the car to the service center but the problem
I will hazard a guess that the problem is heat.
After a long run and then stopping, there is heat build-up
under the hood and this is causing the fuel in the lines to
vaporise and form bubbles in the line.
This is causing the erratic running and stalling.
When the engine has cooled sufficiently, the fuel flow is
normal and this problem does not arise.
Why this is happening in your car in particular I cannot say,
but have you done any wok under the hood which has entailed
moving the fuel lines or there is an additional heat source
close to the fuel lines.
Even adding bodywork extensions, etc can affect air flow
under the hood and cause excessive temperature build-up.