Mercury 700 vapor lock problems
#21
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Join Date: Mar 2007
Location: memphis TN.
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I had the lift pumps replaced before I sold the boat a few weeks ago and the problem was solved. Good fuel pressure at a hot start. The pumps had gotten weak. This was recommended by Mercury. Still a good idea to open the engine hatch's till things cool off.
#22
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This has been a nagging issue with my 700's since I repowered. I have done the reflash, it helped a bit, the boat uses way more fuel now though. I have more problems in Florida on warm days in the winter. Different gas does change the restarts. The 700 does not return to tank! I had Bob Teague install a return to tank system a couple years ago. It also helped but did not eliminate the issue. This year I installed a electric fuel pump bypass. This will allow me to run the electrics for 30 seconds or so prior to a hot restart. This should help push the vapor out of the fuel rails back to the tank. The computer will only run the pumps for a few seconds prior to startup. I have not boated in hot weather since the switch install so we will see !! You would think Merc would come up with a retrofit, I think the finned aluminum fuel rails soak up the heat and boil the fuel right above the heads..but what do I know ?? Two bags of Ice when at Gilberts havin lunch..dunno