On going problem with 2000 Merc EFI 175 Saltwater EFI. In yard on hose sounds like a top fuel dragster (I know about lack of back pressure ). Put in the river and if idle for more than 2 minutes engine will not go beyond idle without stalling. Some plugs will be fouled some not. Clean plugs or install new plugs and engine will not start unless I jack around the throttle. Checked all voltages, fuel pressure, compression and all OK..New fuel line, water separator, fuel filter, dumped fuel, cleaned fuel rail and ran with remote tank same results. Finally today on hose engine exhibited same symptoms as on water , checked fuel pressure only 27 lbs, ran like a three legged dog. Squeezed fuel line from pump and engine smoothed out and sounded great (Guess restriction increased fuel pressure). My question is fuel pump problem or regulator(my guess pump). Does a method exist to check regulator ? Should I take vapor separator apart and clean it ? I made a mistake and brought a non-merc manual and do not have detailed troubleshooting guides(do not want to insult anyone by stating brand name). I have placed a merc manual on order , but would appreciated help so I can get this thing popping!!!!
