90 Corolla 4AFE Intermittent Hard Starting

[91boz]

I am helping a friend with his 90 4AFE Corolla. The problem is intemittent hard starting especially first thing in the morning. The first problem is the engine will turn freely like the timing belt is broken and when this happens there is no spark. Other times the engine will crank but will struggle to turn over like the timing is way off but this time there is spark on all cylinders. Once the engine starts up it runs fine and the problem goes away untill the next morning or sometimes it starts right up!
The computer, distributor and map sensor was all swapped out when the problem was present so they are not causing the problem. The timing belt was replaced along with the water pump but the problem was already present before replacement. Anyone have any idea as to the cause of the problem?

[91boz]

I forgot to mention that the ECU showed an error code #24 "Airflow Temp Circuit"

[retiredat44]

nevermind, i thought it said steering.. not starting.. (hazy eyes ..)

[90 GP]

Have you checked the compression? Were the cap/rotor/spark plugs and wires changed when the distributor was replaced? Have you verified whether the cold start injector is giving a shot of gas when you crank it when cold?

[91boz]

Cap and rotor and coil are all new. Compression was not checked when cold. Car runs fine once started. Disregard the code "24". It never came out again once the ECU was resett. It was probably there cause we had disconnected a few things previously to isolate the problem.
I was thinking maybe it is the starter not engaging but spinning free causing the high pitch cranking sound and the no spark. Also sometimes when it goes into the "hard to turn over condition" , like the timing is way off could be because the starter is not fully engaged with the ring gear? I will tell him to check that next.

[91boz]

The problem turned out to be stale gas. The gas had a strong varnish odor and had a yellow tint to it. Once the old gas was flushed out and refilled with fresh gas the car started up right away. This would explain why the engine would hesitate to turn, probably all that unburned gas in the cylinders causing a hydro lock like condition. Now this does not explain the no spark condition but so far it runs fine but we shall see if anything else shows up.