Class action lawsuit ( mercruiser) vapor-lock issues.
 

You ever wonder why there has never been a lawsuit filed against Mercury Marine for the vapor-lock issues with the older 502mag MPI's and 454mag MPI's? I myself ( just a little guy boater) have talked to Merc. They blame the boat manufacturer for the compartments being too insulated and holding heat as well as not enough ventilation. The issue I see is I have talked to many-many people over the years with many different brands of boats, all the same issue. Go to any boating website and you'll discover 100's with the same issue. Now I get the fact there are 1000's of boats with this same package with no issues. But here is where I bring the argument. 1. Merc. Has acknowledged a problem by offering several different types of fixes most evolving the coolfuel units, none really if you have the VST's.. These fixes are at the consumers cost and very expensive.
2. There are Merc. Bulletins addressing the issue. BUT they mention that the motor compartment cannot reach temperatures exceeding 170 deg. F +\~ a couple.. This is my argument. If EFI engines are designed to run at temps of 160 how would this even be possible to maintain a compartment temp under 170. The heatsink of this motor at shut down has to exceed 220-250 deg.F.. To me this is an engineering flaw regardless of the ethanol based fuels which now make things worse.
3. Safety.. Imagine boating on a river ( with a current) docking. You go enjoy a lunch load your family. Start the boat and begin to pull away and poof, motors gone.. You try to restart as your banging off other tied boats or hit bridge supports etc. I bet it's happened to somebody out there somewhere. I often wonder about people's safety if they got caught in this situation.

My point being, I surprised there has never been a safety issue addressed or formal complaint filed against Merc. Look at the auto industry... Just tossing out there for some thoughts... I myself suffered the same vapor lock issues but have converted entire Fuel system and sh-t canned the VST's..

My old stingray with a 502 MPI vapor locked as I pulled out of the locks going upstream Pittsburgh 3 rivers,,,, Was floating towards the Dam,, Talk about sweating, thouhgt I was going over. Fired back up in the nick of time. I wasnt trying to be Bruce Willis on Striking Distance but felt like him....

was a poor design from the start...they were trying to save $$$ and not having the return line to the tank and all the builders having to deal with that, as then it would not run out of a boat...

i also wonder why mercury has not deen sued over the 525 header issue.

You know I have had 6 boats and never once feared that. Of course all had different motors.. Your lucky we lost a kid over a dam locally here.. Boat would start and it went over with the driver... Merc should have stepped up...

Is it about money you think? It's simpler which makes most boat manufactures happier too. I just open my hatch after running hard for a couple minutes after shutting down. You are right though, return line would probably eliminate this concern.

Return to the tank and routing the plumbing not so close to the block would probably a help a ton.

I actually did the return thing first, even relocated the water separator/ filter to the bulkhead behind the seat in the engine compartment to get it away from the motor.. Installed all new braided lines with AN fittings.. This helped but would still happen on hot days after running semi hard... After some investigating it looks to be vapor locking at the mechanical pump. It always starts right up and then runs the vst dry.. Then my fuel pressure gage would sit at zero... Yes, I checked the pick ups and vents,, all good... Even installed another fan to bring in cooler air while two our removing.. Figured why fight it.. Costs a couple grand to be done with the entire mess..

Oh I know, I'm in the process right now and your help has been greatly appreciated.

I have another question for you but I'll email it.

Im not sure but it seemed to help last summer to grab some ice from the chest wrap it in a towel and stick it on the vst. I too will be changing this crap out!