Ok, I am about at my wits end on this. My 99 4-stroke was not laid-up properly before being stored for about 3 years. Now it doesn't run worth a darn. I have been troubleshooting and cleaning and replacing parts for about a month and a half now and while it runs a bit better, I still couldn't get it to run decently when loaded this weekend at the lake.<br /><br />Basic symptoms: Starting is not bad, though I do have to advance the throttle the first time I start it after an extended rest period... once the engine is warm it starts fine. Idle is rough - it will jump up to 1500 or so RPM and then come back down to 800 or so... then falls to 600 and occasionally dies.<br /><br />Unloaded (on a flush rig), I can run the engine up to 6000 RPM with no problem... though I might detect the occasional miss. Loaded (in the water) it will often die when going into gear, but if I am gentle, I can feather it up to about 2000 rpm (5 mph on water)... but if I push it past that it dies instantly. I used to run WOT @ just below 6000 rpm and 25-30 mph.<br /><br />I notice that there is a fair amount of air in the fuel filter while the engine is running... nothing I have done has made much of a difference to this and the local mechanic says it is normal, but I have my doubts. The primer bulb does not collapse when running, but is a little squishy. Pumping it seems to have no effect on the behavior of the engine. Neither does opening the gas cap. The gas is fresh and stabilized.<br /><br />So far I have done the following:<br />Replaced the Fuel Filter<br />Replace the Quick Connect Fitting on the Tank Side<br />Replaced the Primer Bulb and hoses<br />Cleaned and rebuilt the fuel pump (it was a bit gummy inside, the thin diaphragm looked a bit stretched, so I replaced it and the o-ring)<br />Cleaned the carburators (they were pretty clean to begin with)<br />Changed the Oil<br />Compression Test (all cylinders are at ~190-195 psi)<br /><br />The engine only has about 75 hours on it and looks almost brand new, so it is disappointing to have this much trouble with it.
