Bought an 81 Sea Ray runabout last summer as my "first boat" to take the kids out on the lake. It has the infamous 470. I do not know much about the history, but I bought it at a local Marina who had it on consignment. The Marina was very helpful and showed me all the ins and outs (this being my first boat) and they claimed to have compression tested the motor, but they didn't water test it (it was rather cheap as it needs some interior work so I doubt anything was done other than putting it on the lot). I ran it most of last summer without touching a thing on the motor. It was running a little hot (never in the red, but got to within about 10% of it one hot day while towing a tube), so over the winter I took the outdrive off and replaced the water impellar and housing. I also replaced the thermostat, acid washed the 4" exchanger, and replaced the fuel filter. All of the parts actually looked Ok so I think the previous owner took care of it (although the tstat housing had blue goo that had hardened partially blocking the water flow because whomever worked on it last used too much gasket stuff).
Anyways, on to my problem, the engine fires up, idles and purrs perfectly when cold and runs great UNTIL I shut it off. Once I shut if off to swim/eat/etc for 30 minutes or so, it starts back up fine, however, when I take it up to mid throttle to plane it out on the return trip, sometimes it will stall / hesitate / die. I first thought it was vapor lock, however, yesterday I was very careful not to let it get too hot and also let it idle for 5 minutes before shutting it off. Again, started fine, got up to speed fine, then about 2 minutes later it tried to stall out. I could touch / grab the metal fuel line between the carb and pump and it only felt warm, not hot. I touched the carb housing and just warm, not hot. When it stalls, if I pump the throttle a few times it will come back to life so I'm thinking it's not getting fuel. If it does die, I can usually get it restarted rather easily.
So, if it's vapor lock, why does it only stall after shutting if off and not stall when the engine gets very hot beforehand? If it's not vapor lock, what else could it be? I would say fuel pump, but again, it runs perfect until I shut it off. I'm thinking maybe bad gas as I think it does it most often right after I fill up the tank, but again, wouldn't that cause it to run bad before I shut it off too?
Any ideas on what else to check?
Anyways, on to my problem, the engine fires up, idles and purrs perfectly when cold and runs great UNTIL I shut it off. Once I shut if off to swim/eat/etc for 30 minutes or so, it starts back up fine, however, when I take it up to mid throttle to plane it out on the return trip, sometimes it will stall / hesitate / die. I first thought it was vapor lock, however, yesterday I was very careful not to let it get too hot and also let it idle for 5 minutes before shutting it off. Again, started fine, got up to speed fine, then about 2 minutes later it tried to stall out. I could touch / grab the metal fuel line between the carb and pump and it only felt warm, not hot. I touched the carb housing and just warm, not hot. When it stalls, if I pump the throttle a few times it will come back to life so I'm thinking it's not getting fuel. If it does die, I can usually get it restarted rather easily.
So, if it's vapor lock, why does it only stall after shutting if off and not stall when the engine gets very hot beforehand? If it's not vapor lock, what else could it be? I would say fuel pump, but again, it runs perfect until I shut it off. I'm thinking maybe bad gas as I think it does it most often right after I fill up the tank, but again, wouldn't that cause it to run bad before I shut it off too?
Any ideas on what else to check?