Instant Starts

[Constant Mesh]

My FJR engine starts almost instantaneously. My Honda and Acura car engines crank a while before firing off.

Are there design choices/considerations for how quickly an engine starts?

 

[chrisflock]

I know one thing that can make that sort of difference is fuel delivery. The FJR doesn't exactly have a long fuel line, so it doesn't take much for the pump to get fuel pressurized and flowing out the injectors. On a car with the pump way back in the tank, it can take a while to build up enough pressure to get fuel squirting...

Additionally, there are some other design considerations that affect this. Many cars use an oil pressure safety switch, with no oil pressure, the fuel pump won't kick on. Some models use a relay to 'bypass' this mode when the car is starting, while others may actually not turn the pump on until the engine has built up 'enough' (read a couple PSI) oil pressure to satisfy the sensor.

 

[Ramblin Man]

I know one thing that can make that sort of difference is fuel delivery. The FJR doesn't exactly have a long fuel line, so it doesn't take much for the pump to get fuel pressurized and flowing out the injectors. On a car with the pump way back in the tank, it can take a while to build up enough pressure to get fuel squirting...
Additionally, there are some other design considerations that affect this. Many cars use an oil pressure safety switch, with no oil pressure, the fuel pump won't kick on. Some models use a relay to 'bypass' this mode when the car is starting, while others may actually not turn the pump on until the engine has built up 'enough' (read a couple PSI) oil pressure to satisfy the sensor.

+1

Also, most cars I've worked on also look for engine spark before turning on the fuel pump or fuel injectors.

Still in the case of your car, look for something called the accumulator. It is supposed to hold pressure in the fuel system. If yours is bad (if you have one) it will allow the pressure to bleed off requiring longer starting times.

 

[BrunDog]

I don't agree. The fuel system pressurizes when you turn the key on. Don't you hear the fuel pump cycle?

A rotation or more of the crank is needed for the CPU to determine the crank angle. It is an incremental encoder without any memory, so it must "index" before the CPU knows where the crank is and when to apply ignition and fuel pulses.

-BD