I have a '93 150hp Mariner that works fine when first put in the water (I trailer the boat). However as the day goes on, the motor stutters and stalls on acceleration... generally gets worse as the day goes on (and I think as the day gets warmer). When running at it's worst, I can't even go directly to full throttle without it dying. I've had the boat in to three different marine dealers, one of them had the boat on the water. I installed an antisiphin valve, changed the bulb and hoses, one of the dealers worked on the carbs, changed plugs, checked plug wires and spark in general, and did a compression check on the engine (checked ok). <br /><br />I've ran several different bottles of Merc. carb cleaner through the engine but that didn't change anything.<br /><br />I rebuilt the fuel pump.<br /><br />Any suggestions of what to look at next?<br /><br />One other thing that may or may not be related.. WOT "sounds" and seems to run great but the tack never reads above 4500. I tried a couple of different prop sizes to the point it sucked air on accelleration but the tack never reads above 4500 on full throttle (the linkage and carbs are open). Tack was replaced twice with new ones both times. Both the dealers and I checked the setting on the back side of the tacks against the manual. <br /><br />I also replaced the rectifier and stator. Voltage/charging is good.<br /><br />Again, any ideas of what to check next?
