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View Full Version : Mercury Tech stalling 2.5 merc


redsnapper386
06-02-2019, 06:10 PM
guys i have a 1993 2.5 v6 200 hp merc off shore, it is hard to start cold , idles rough , but the main concern is when i reach 4200 rpms it stalls back to 3000 rpms and lower. all parts are new fuel pump,stators triggers fuel lines,gas vent line ect ,anti siphon valve taken out,carbs are rebuilt .im stumped any ideas thanks. once it is started it starts right up.if i give it a little throttle cold it will start.thanks.
H2Okie
06-02-2019, 08:08 PM
sounds like it's running out of gas . Fuel line restriction , fuel pickup screen in tank ? Try a portable tank with known good fuel and see if the problem clears up .
redsnapper386
06-02-2019, 09:25 PM
sounds like it's running out of gas . Fuel line restriction , fuel pickup screen in tank ? Try a portable tank with known good fuel and see if the problem clears up .
thanks will do
tlwjkw
06-03-2019, 06:53 AM
whats your "cold start" procedure?.. some carb mercs can be finicky as hell till warm..
redsnapper386
06-03-2019, 04:20 PM
whats your "cold start" procedure?.. some carb mercs can be finicky as hell till warm..
push key in hold for 7 seconds release key start,enrichner valve is new. thanks
tlwjkw
06-03-2019, 04:32 PM
try it this way..

pump bulb up till firm..
trim ALL tha way in..
push and hold enrichner while crankin' till it pops, farts or something similar then release both start and enrichner..
trim up to level or a tad positive..
raise fast idle justa tad..
start without enrichner pushed.. this may vary a little. you may/may not have to slightly "bump" enrichner while turnin' it over this time..

most carb mercs jus flat don't like idlin' trimmed in.. keep it at least level..
redsnapper386
06-03-2019, 05:24 PM
try it this way..

pump bulb up till firm..
trim ALL tha way in..
push and hold enrichner while crankin' till it pops, farts or something similar then release both start and enrichner..
trim up to level or a tad positive..
raise fast idle justa tad..
start without enrichner pushed.. this may vary a little. you may/may not have to slightly "bump" enrichner while turnin' it over this time..

most carb mercs jus flat don't like idlin' trimmed in.. keep it at least level..thanks again thats good info the boat is on trailer in driveway on hose i keep the trailer jacked up for rain and water drainage.no doubt the elevation is the culprit. will try it level.