I'm looking for help diagnosing a starting issue on my 1989 C4 Corvette with a 6-speed. On a cold start, it always takes more than five seconds of cranking to fire up, and sometimes it won't start on the first attempt. Interestingly, if I do an initial crank for a couple of seconds, stop, and then crank it again, it starts almost instantly. The problem gets worse with hot starts after the car has sat for a few minutes; it restarts perfectly if I shut it off and turn it back on right away, but if I wait for several minutes, it becomes even harder to start than when it's cold. I performed a fuel pressure test and found that with the ignition on but the engine off, the pressure jumps to 40 psi but then quickly bleeds down and settles at 20 psi. While the engine is running, however, the pressure holds steady between 38-42 psi. I also know that at least one of my fuel injectors is weak or failing. Based on this, I'm assuming the pressure bleed-down is from a bad fuel pressure regulator and/or leaking injectors, which could also explain the difficult hot starts if a cylinder is getting flooded. Before I spend the money to replace both the injectors and the regulator, I wanted to ask if this diagnosis sounds correct or if there's anything else I should check first.

 

Hello, pinch off the return hose and see how it holds prime. This can help you isolate injectors vs. fuel pressure regulator. (My FPR was experiencing a soft failure until I pinched the line after which it faile completely!) Let us know!

 

If they are the original injectors, I would replace them anyway. As mentioned, do the pinch tests and isolate pressure loss area.