5.7L Mercruiser hard to start after fully warm

[Miwhay]

Hey guys, I have a 1996 Bayliner 2252 with a 5.7L Mercruiser. I got it from my in-laws back in 2009 as they had it sitting in a garage for about 10 years. I pumped all the gas out of it and rebuilt the carb as the gas had varnished. Once I ensured it was clean, I started it up. The boat runs beautifully with great cold starts and idles perfectly. Performance while running is perfect as well. The only problem I have is that once it is heat-soaked and I shut it off, say, to change skiers, the engine starts as if it is flooded. I have to go to wide-open throttle to start it back up and then it is back to a beautiful idle and great running. Any ideas on what this may be? I talked to someone at Mike's Carb in WA and he thought the fuel may be getting too hot and boiling. I am not sure how to correct this even if the fuel is getting to hot. Again, with the hose hooked up to it in the driveway, I can't reproduce this condition. Must not be under enough load to get the temp I need to simulate this condition.
Any help is appreciated.

 

[SDSeville]

Re: 5.7L Mercruiser hard to start after fully warm

I am no expert, but it sounds like vapor lock (or as the carb guy said "fuel boiling"). Do a search here for vapor lock and see if the symptoms match. I had it on my boat and wound up wrapping the fuel line with insulation and installing a blower (on separate switch) to blow directly on the carb and fuel line when I stop/restart.

The fix worked great, but it makes me wonder how the boat started just fine without the insulation and blower for the past 25 years.

 

[alldodge]

Re: 5.7L Mercruiser hard to start after fully warm

Hey guys, I have a 1996 Bayliner 2252 with a 5.7L Mercruiser. I got it from my in-laws back in 2009 as they had it sitting in a garage for about 10 years. I pumped all the gas out of it and rebuilt the carb as the gas had varnished. Once I ensured it was clean, I started it up. The boat runs beautifully with great cold starts and idles perfectly. Performance while running is perfect as well. The only problem I have is that once it is heat-soaked and I shut it off, say, to change skiers, the engine starts as if it is flooded. I have to go to wide-open throttle to start it back up and then it is back to a beautiful idle and great running. Any ideas on what this may be? I talked to someone at Mike's Carb in WA and he thought the fuel may be getting too hot and boiling. I am not sure how to correct this even if the fuel is getting to hot. Again, with the hose hooked up to it in the driveway, I can't reproduce this condition. Must not be under enough load to get the temp I need to simulate this condition.
Any help is appreciated.

:welcome: to iboats

I think you need to check your float level. My thought is your dripping fuel when hot do to expansion. When hot shut it off as usual and remove the flame arrester, then look down the carb. If you see fuel your carb needle seat is either leaking or your float level is to high

 

[not enuf toys]

Re: 5.7L Mercruiser hard to start after fully warm

just another idea - mechanical fuel pump going out?

when the diaphragm starts leaking, it pushes the extra fuel into the carb (instead of into the hull or the ground like a car). this can cause the bowls to over flow and leak into the motor.

after a long hard run, does it want to stall? does the sight tube have fuel in it?

 

[dubs283]

Re: 5.7L Mercruiser hard to start after fully warm

verify upon shutdown if fuel is dripping down the carb, if so pull the carb and inspect, clean, rebuild, etc...