'70 Mercury 1150, sn: 2840981 <br /><br />On dry land with muffs, I can crank it, and it cranks easy, let it warm up, return the advance lever to normal and it has a nice idle.<br /><br />I take it to the lake and it's difficult to start. It will start eventually, just have to prime the top carb with some fuel. It will not stay running when I return the advance lever to normal.<br /><br />Spark is good and plugs are new, trigger is good, fuel getting to the carbs is good, firm pump bulb<br /><br />I, also, still need to check compression.<br /><br />I had this ready to post then found some related information. I will need to check these things out but I wanted to get my post up anyway.<br />
Clams Canino thread:<br />Timing and Sync of Merc Inlines (to 1988)
Laddies & Clams Canino post:<br />...Usally a motor that will idle on a hose but not in the water needs carb attention first, some have a lower main seal out,...<br /><br />...If it can idle on the muffs the reeds (and blocks) are probably good enough to run right...<br /><br />...If the motor is overpropped for the boat it'll do the same thing, ditto if the carbs are too lean, or the timing and sync is off...<br />...but it's more likely to be mis-adjusted or overpropped as opposed to having worn out reed blocks.<br />
Ed Mc. post:<br />A dyno may not simulate the backpressure of sitting in the water. You can try increasing the idle speed. If there's a mixture adjustment on the carbs, you'd want to adjust the needles to richen the mixture (CCW).<br /><br />How about a compression check, has anyone done that?<br /><br />You also may have issues with the upper or lower crank seals; loss of crankcase vacuum will affect idle quality, especially in the water.<br /><br />Has anyone checked the plugs for water after one of the 'dying' incidents? If you find water on the plugs you could have leaks from the exhaust manifold or gaskets.
So maybe I already have the answer, once I check these things.Trent post:<br />Time to remove the carbs and install overhaul kits. Clean very well with carb cleaner. And when your done........Clean AGAIN!!<br /><br />Your engine runs good on the "hose" because it does not have back pressure on the exhaust system.