Problem starting

I have a AHU engine that periodically doesn't want to start. It turns over fine but it's like there is no fuel. If I leave it a few hours and go to start it again it will then fire up. Only does it ever so often. What's people's thoughts?

Which type of fuel system do you have?
Carbed, or CIS.

Cis

Not being a CIS guru, or ever owning one, I would say look first at the Accumulator to see if you remove the one screw to see is Fuel is present, if it is then the accumulator is bad.

Second thought is that the Fuel pump check valve is allowing the fuel to drain back in to the tank and there is lack of fuel in the system to start.

Do you wait 4-5 seconds after inserting the Key in the ignition and the run position of the switch prior to the Starting of the car, this allows the Fuel pump to Prime and pressurize the system.  I have seen on my EFI cars Honda, Pissan Nathfinder, Saturn, and my Cabriolets that failure to allow the system to prime can flood Cylinders with unpressurised injected fuel flooding the engine and that waiting for the flooded cylinders issue to dissipate the system is pressurized and can now start.

Duty cycle is another issue as well as the WUR and 5th injector not working.  

So try to wait 5 seconds prior to engaging the starter and see if that isn't the issue, then I would strongly suspect the check valve on the CIS engine.

Give me some things to look at. Thanks

I know this is an old post, but only just seen it, this used to be my caddy many years ago. I'm guessing you find the issue by now? But it used to blow a relay on the fusebox every so often when I had it, and how the ecu was wired and you had to wait for it to reset.