age old ?,how to stop vapor-lock,vst system
 

i know you guys get tired of reading these same old posts,but i need help.1994 502 mag,efi.after running hard for awhile and when i shut down for more than a hour,my engine will vapor lock.it will start ok and idle,but when i go to get on plain,it will spit and chock,and then clear up.i have r/r the mech.fuel,cleaned/flowed the injectors.temp is about 140.where is the vapor lock at?the mech.pump,lines,or high-pressure pump?i would really like to keep fuel injection,but a carb is looking pretty good right now.anybody?thanks

Per Mercury Tech Bulletin from a few years ago.

· Let the engine idle for 3-5 minutes before shutting it off.
· Opening the engine cover to let the hot air escape.
· Operating the bilge blower to remove the hot air.

To my knowedge there is no 100% fix for this.

Mercury had the same problem with the 575s early on. The problem was most evident with "Winter gas". Is this when you have problems? If so there was a kit to correct this problem. I think the kit had a check valve along with some other items. If it helps I may be able to find the kit number. Mercury only installed the kit AFTER the customer reported problems. Hope this helps.