Long crank time is usually due to fuel pressure bleeding off while it's sitting. If it's due to a leaky injector, you might see some black smoke out the tail pipe at startup. The worst part of this would be the raw fuel seeping past the piston rings into the engine oil. During long trips, (15 miles or more), that fuel will mostly vaporize and be drawn out and burned. If you do a lot of short trip driving where the engine never really warms up, which is always hard on an engine, that fuel will reduce the oil's ability to lubricate internal engine parts.
Sometimes running a fuel system cleaner in the gas can help the injectors seal better. I'm not sure what a dealer could do to temporarily mask this problem. More likely, varnish built up around the injector pintle valves over time, and now that you're running new gas with cleaning additives through it, the varnish is going away allowing fuel to seep past the valves.
Another, less common cause of low pressure is leaking valves in the pressure regulator and a leaking check valve in the fuel pump. Neither of these will cause any problem other than the long crank time.
One way to tell if fuel pressure is low at startup is to cycle the ignition switch to "on" for a few seconds without cranking the engine. Turn it back off, wait a few seconds, then turn it on again. Do that a third time, then crank the engine. If it starts instantly every time you do that, dropping fuel pressure is the cause of the long crank time. When you turn the ignition switch on, the fuel pump runs for two seconds to be sure fuel pressure is up in preparation to start. Then the pump turns off until the engine computer sees engine rotation, (cranking or running). By cycling the ignition switch multiple times, it runs the pump longer which insures full pressure is there when you crank the engine.
If this works, I would first recommend running two to four tanks of good quality fuel through it, then see how it acts. If the long crank time doesn't improve, I'd suggest a fuel system cleaning. Your mechanic will attach a pressurized can of detergent to the fuel rail on the engine. The engine will actually run on this concentrated chemical. Another product will be added to the tank to clean that part of the system.
If that doesn't help, the mechanic may remove the fuel rail with the injectors attached to watch them to see which one(s) is leaking.
I also found a cut O-ring seal on a pressure regulator once. It took about five seconds for that engine to start, but it ran fine once started. With a pressure gauge attached to the fuel rail, you could see the pressure drop off within a few seconds after turning off the engine. Normally that pressure should hold for days or weeks.
Caradaiodoc
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Thursday, April 23rd, 2009 AT 3:13 PM
