I've been having issues with starting my 91 Volvo 740, (we thought it was the starter, but because it starts most of the time we're looking into issues with the flywheel) but I noticed that when it didn't want to start putting it in gear and then back in park sometimes helped. Then one time I put it in reverse gear and took my foot off the brake and it started rolling backwards down the hill, with the engine not running.

I tested this out again later and the car only rolls down a hill in the same direction as the gear. i.e. backwards down a hill in reverse and forwards down a hill in drive.

Is this normal? if not, how can I further diagnose and fix the issue?

 

I think that's normal, I wouldn't worry about it... unless the car was in Park? If so, it'd seem that you have shifter issue, and that is a pain to repair! The shifter has a lock solenoid and micro switch depending on model year, a neutral safety switch, etc. Pulling the **** is a bear, desoldering the OD button is no fun. It's all fiddly and hard to diagnose exactly--I just did one on a '94 940 and gave up on repairing it, got a used one and called it a day.