Why is My 2005 Chevy Corvette Exhibiting Extended Cranking?

Q: I have a 2005 Chevrolet Corvette with a 6.0L engine. When I start the car cold, it fires right up. But when I turn the engine off and wait, say, 15 minutes to an hour or so, it exhibits extended cranking and takes a few seconds to start.

I have had a fuel pressure gauge on it when this happens, and the gauge reads 60 psi as soon as the engine starts cranking. I have already replaced the camshaft position sensor and there are no codes.

Once the engine starts, it runs just fine. Acceleration is great, and the car does not miss a beat. Mileage is 25 MPG on the road. I am at my wit’s end as to the cause of the concern. I have not found anyone else with this problem that has come up with a solution.

I have attached some videos along with my question.

– Dan from Florence

A: Hello, Dan. There are many potential causes for your concern, but I would start by looking at the fuel system more closely.

Your Corvette has an interesting returnless fuel system with two fuel tanks and two sending units. The left side fuel tank contains an electric fuel pump and regulator that supply fuel to the injectors. There’s also a secondary fuel pressure regulator in the right side fuel tank. A fuel pressure check valve resides in the left side tank. 

To prevent long cranking, the check valve, primary fuel pressure regulator, and secondary fuel pressure regulator work together to maintain fuel pressure in the fuel feed pipe and fuel rail.

The first thing I would do is check static fuel pressure (key on, engine off) and fuel system leak down—it doesn’t sound like this is something that you’ve done yet. If the system isn’t holding pressure, the issue can cause hard starting and vapor lock once everything is warmed up. 

To check for static fuel pressure, hook your pressure gauge up, as you did before, then turn the ignition key to the “ON” position (don’t start the engine). Monitor the gauge for about 5 minutes to see if the pressure drops.

If you find that the pressure does not hold, you may be dealing with a leaking fuel line, a faulty check valve, a faulty regulator, or leaking injectors. 

To determine whether the issue is a leaking injector or a problem elsewhere in the fuel system (i.e., leaking fuel line, faulty pressure regulator, etc.), install a fuel line shut-off valve in series with the fuel pressure line (or block the line in some other way). Run the pump so that there’s fuel pressure, then close the shut-off valve. 

Should you find that the pressure still leaks down with the fuel pressure line blocked off, you know you have an issue at the fuel rail, such as a leaking injector. On the other hand, if the pressure now holds, the problem is elsewhere in the fuel system. You may be dealing with a leaking fuel line, faulty check valve, or bad regulator. 

C6 Corvettes are known for having the fuel pump fitting on top of the tank crack, which is a possibility. So, keep an eye out for that. 

Also, unfortuantely, I did not find any videos attached with your question.

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