Quote:
Originally Posted by Tidybuoy
There's a third part of the equation and that is the fuel pump check valve. This is a one way valve that prevents fuel pressure from leaking down after the car is shut off.
By keeping the pressure up, even when the car is off, it enables the car to start on the first few cranks - otherwise the system would have to build up pressure before having enough fuel pressure to squeeze fuel thru the injectors - taking 10 or 20 cranks before the engine will start.
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the system does retain fuel pressure, provided the injectors close properly and the check valve is working as it should. you can do a test install a guage run it then watch how long it maintains pressure..
10-20 cranks , I dont think i agree with that..
actually the fuel pump comes on with key on and primes the system anyway. it might help it start a tad quicker. I dont think it's unusual for the pressure to leak down overnight past the check valve.
it is possible though, if an injector doesn't close properly to get a bunch of white smoke upon startup if you do have an injector stuck open. that can dump a 1/2 teacup or so of fuel into a cylinder... it is possible if a cylinder gets full of fuel , to break the engine with the starter.. check for that if you notice a white cloud of raw fuel smoke upon startup. I've had that happen. when I saw it my volvo would blow white smoke for a block, then run normal most likely just one injector gets stuck so it is localized. I also had one stick closed, no fuel and the engine then basically ran on 3.. the symptom was a rough idle and lacked performance. Its surprising how well an engine can run on 3 though..