New injectors on a 95 4.0 but have long crank on warm start. Think I have an injector bleeding down into 1 of the cylinders. Here's the scenario.
Morning cold start immediate no matter what out door temp is
shut truck off and restart within say 10 minutes, starts immediately.
problem comes when truck has been run and shut off and your attempt to start from 20 minutes to as long as 2-3 hours later. result is and extended long crank with an eventual start and odor of fuel. Don't think fuel pump is bleeding off or would definately have long crank on first morning start, it does not.
How can I determine which injector or injectors may be spilling fuel into cylinders while truck is off, bleeding off fuel pressure. Hope to do this without tearing injectors out to test individual.
Also could a leaking diaphragm on fuel pressure regulator cause a bleed of fuel pressure into the intake, causing a rich condition on start up. My theory is it bleeds into intake or cylinders but given enough time, say overnight it evaporates and starts fine. Quick restart does not give it enough time to cause rich condition.???
motor runs well, maybe down on fuel mileage, rebuilt 7K ago, 6 brand new injectors,

 

Well if injector was leaking then you would lose all fuel pressure, warm or cold.

1995 will still use Fuel Pressure regulator(FPR)
Its just behind alternator
Has the Fuel Return line and a vacuum hose attached
Check that vacuum hose for gasoline or gas smell

Not an uncommon issue for FPR diaphragm to leak.
Cold engine NEEDS a rich air/fuel mix
Warm engine does not like it
As you brought up

Vacuum hose fills up as engine sits and FPR leaks, at start up it gets sucked into intake by the vacuum


Easy test for leaking injector, assuming no gasoline in FPR Vacuum line
All fuel injection computers have a Clear Flooded Engine routine
Turn key on
Press gas pedal to the floor and hold it down all the way
Key on, RPMs at 0, Gas pedal(TPS) at WOT, wide open = Clear Flooded Engine
Computer will turn off Fuel injectors, but leave spark on

Now crank engine, it should not start or even fire, no fuel is coming in
As soon as you release gas pedal, computer will start injectors instantly
Or if engine does fire and RPMs get above about 350 then injectors will start.

You should do this test when engine is warmed up.

If engine does fire, then you can find which injector is leaking using the same test
Unplug coil packs 4 wire connector, so no spark

Set Clear Flooded Engine and crank the engine over a few times
Pull out spark plugs, they should be DRY, WET one has the leaking injector