My friends 86 Z28 with a 355TPI engine has a starting problem, it needs to crank over a bit before it will start.
At first we though it may be the the cold start injector, so I burned a prom for an 89. Still had the same problem.
So I decided to use a pressure gauge to check the pressure.
Pump primes, pressure hits 43psi, then drops immediately to 0psi.

So, I clamp the return line when it primes and it goes up and then back to zero.
I do the same to the feed line, and it goes up and then back to zero.

So, just for the heck of it, we swapped fuel pumps since the old one was good and the new one was put in a few months ago.
Same problem, 43psi then down to zero.

So now I put 12v power straight to the pump and we hear a leaking sound coming from the pass side of the fuel rail/intake, near cylinders 2 & 4. This leads me to believe that one or two (possibly more) injectors are leaking, but I've never heard the sound of one that leaked.

Does this sound like a leaky injector(s) to you guys?

Thanks

 

Pressure regulator?

 

Wouldn't clamping off the return line show that the regulator is working?

 

Yes.
and
Yes.

 

When my inj's were leaking, taking off the TB bellows tube and opening the blades, sounded like a hissing noise.

 

We can hear that hissing sound without taking anything apart.
He ordered a new set of injectors, should be here Friday and we'll install them on sunday. hopefully that fixes the problem.
Oh, and the fuel pressure regulator is only a few months old.