How many lbs of compression should a 500 have mine has 75 and won't start. At first I thought it was a ECM, but I am having second thoughts.

 

hello i beleve that i heard thear is a auto decompresion on them but i am not shure

 

just a guess but around 100 psi. could be bad rings or bad valves not closing. imo.

 

The information I have from a RepairPro CD for the 500 is that the compression should be between 60-90 lbs. It mentioned that low compression could be caused by a decrompressor problem. It sounds like yours is okay, compression-wise.