Stock 86 iroc. Starts fine in the morn when cold. When its warm it takes a lot of crank n to get it fired again. Any ideas what i should be looking at?

Thanks

 

Do you notice an audible difference in engine crank speed between cold and warm weather / engine temp?

Warm batteries perform less efficiently than cold batteries, believe it or not. You could be a few RPM's short of a quick startup. This particular issue can be cured by a new battery 70% of the time.

If your battery is relatively new, and you're still hearing a difference in crank speed, it may be time for a new starter, as hot motors also perform less efficiently than cold ones.

If you don't notice a difference in crank speed warm vs cold, you might be experiencing a Heat Soak / Vapor Lock issue. I'm not sure if your engine is TBI or Carb (relatively new to the F bodies), but either way, you should look for fuel lines that are close to the exhaust manifolds, and put a thermal wrap on them, or relocate them away from the heat source. Heat Soak happens after you shut off the car, the heat levels continue to rise for a while, and cause fuel in the lines to evaporate, blocking the line for several seconds, sometimes for much longer. This can cause a Delayed start / No start condition.

There are a few more issues that can cause a delayed start when warm, but those are the most common, and first to check.

 

neither, it should be TPI (MPI) unless its been significantly altered.


Is the problem a) weak rotation or b) the rotation seems ok but wont fire until after significant revolutions?

if a: Check your base timing on your distributor, Too much advance can cause the spark to work against rotation. Check your terminal connections at the battery and at the starter. Corrosion could be hampering an already weak battery situation. Check your engine grounds and make sure they too have good contact.

if b: Try testing with the pedal to the floor. This enters "flood mode" on the computer and reduces injector output. If this seems to help you probably have a leaky injector or two, OR you have an overpressure situation do to a bad regulator or a plugged return line.
Second test to do is to preprime the system repeatedly (Listen for the fuel pump when you turn the key). Try very short bursts on the starter, allowing the pump to run its couple of seconds after each attempt. If this helps it start sooner then your problem is likely pressure leakdown due to a bad regulator, check ball in the pump or a weak supply from the pump and/or plugged fuel filter.

alternatively, if you have access to one is to plug in a fuel pressure tester to the fuel rail and monitor its readings under various conditions.

Other possible condtions that could contribute are a stuck open EGR, distributor problems like a failing ignition module, a bad or misadjusted TPS, and a coolant temp sensor out of spec (too high resistance).

 

On top of the advice you've already received, take a look at your ignition tune. How are your plug wires, plugs, cap and rotor. Does the engine run okay when warm, once it's started? Thing about checking the injectors or having them serviced.