G'day,<br />I was recently given a 75 Larson 15' boat with a 85HP Evinrude 4 cyl. on it.<br /><br />The boat has sat up for several years with gas in the take and carbs. Tank was rusted out and I have replaced it.<br /><br />I have replaced the plugs, checked all 4 coils, cleared the jets, cleaned the carb bowls, floats, needles, etc. I do have good compression on all 4 cyl.<br /><br />Here's the problem, the engine will not run for more than 10-15 seconds or it will run fine out of the water with a hose on it, but when I put in on the ramp it will not run for more than 10-15 seconds with the motor in the water.<br /><br />I am not much of a 2 stroke mech. It looks like the fuel pump (vapor pump?) has a bad diaphgram, it is not ruptured or leaking, but is indented/formed, I guess I would say it's "not flat" say, could that be causing the problem?<br /><br />The plugs are coming out wet and black, the motor appears to run alright out of the water, but when any backpressure is placed on the motor from the exhaust side (i.e. putting it in the water) it starts pukin' on me. I know this is long, but I have spent my whole darn weekend at the lake with the cover off the motor and have exhausted all my "theroies".......<br /><br />I have :<br />Good fuel/oil mix<br /><br />spark, (coils ohm'ed at 2.25k across the plug wire to ground, I guess that is good all 4 were the same and I don't have a manual)<br /><br />fuel flow is there, I pulled the reed manifold and the intake reeds are clean and in great shape. Floats, jets, needles are clear and working.<br /><br />The only thing I have not done is pull the flywheel, but that is coming next. <br /><br />Any help/specs are greatly appreciated......<br /><br />Thanks
