I have a 2001 Launch with the 5.7L Indmar 350 EFI direct drive. Have enjoyed 10 straight summers of perfect worry free use until this season. When I start my boat up in the mornings and go out everything is fine, but when I park it in the afternoon for a few hours it will not restart. It is as if the engine is deprived of fuel. If it does start, it will barely idle for 10-30 seconds then die. A couple of times it would even start and idle at various speeds by itself before eventually dying. The first time it happened was the first day I had it in the water so I had not changed the fuel filter yet. I bought one during the week and put it on the next Saturday morning before going out. Again it started right up and operated fine all morning, but same problem when I went to run it in the evening. This made me think I had bad gas or water had accumulated in the tank. That week I bought another filter, some HEET water treatment, and topped the tank off with 15 gallons of premium fuel. Added all of these things the next Saturday morning and the boat started right up and ran amazingly well, but same problem when I went to take it out in the evening. I had done some research on the topic and it sounded like vapor lock so I stored it with the clamshell open this time to try to prevent the 'heat soak' but it didn't help.
I have seen various threads on similar things happening but few definitive answers. Everything from vapor lock to bad gas to bad fuel pumps. Hopefully someone in the Supra community can help me nail it down. If it is vapor lock why would it just start to be an issue now? Fuel pumps appear to we working fine also so I would hate to start replacing unncessary parts.
Thanks in advance!