It has a 4-cylinder, 2300 cc gasoline engine.

When the engine is cold, it starts fine.

When it is hot (stopping the engine less than 1 hrs), it starts a little more difficult, but still starts.

But if it is warm, say, after stopping the engine for 1-2 hrs, the engine cranks but won't start... Depresssing the accelerator while starting sometime helps... but sometime doesn't.

After 3 hrs, it starts fine again.

What should I check?

Thank in advance.

I have an 87 740 with 230,000 kms.and was going to take a long shot and agree real quickly with the hall sensor posted below,but your problem sounds similar to mine.The symptoms you refer to were kind of in the begining of my troubles I had years ago except mine would miss fire, kick out and die while driving. For some reason I would let it sit for Play the same way you and be on my marry way until once was too much. I always thought I had spark when I checked.I searched heavy and it lead me to 700/900FAQ and followed all the info for hall sensor and changed the whole distrbutor for 20CDN. from a wrecker.You'll see why I did that later.
Now I have new problem a will post my own new message above wish you luck.Dieter

1. Next time it fails, check the tach as you crank.
2. If the needle doesn't bounce a little, chances are your hall sensor is failing - it goes intermittent initially, especially when warm. THIS IS THE MOST LIKELY FAULT IN YOUR CASE.
3. If the needle DOES bounce, listen for the fuel pump humming for a second as you release the key. If quiet, suspect the fuel pump relay - common failure. Could also be the pump itself.
4. If the tach is dead but the fuel pump hums suspect the power stage.
5. If the tach needle bounces AND the pump hums suspect the coil.

This all assumes you have checked all LT and HT ignition leads. Regards.
--
BillB