low RPMs at WOT

[87Stratos]

I'm going to try this again. I posted this question once but it was deleted for some reason.<br /><br />I have a 1987 Stratos 179V - 150 hp Mercury BlackMax XR2<br /><br />The boat ran great all season. By running great I mean, jumps out of the hole quick and plains off quick and runs 60 MPH (with still some throttle left).<br /><br />Problem....<br />Merc bogs down at 1800 RPMs. When bogging down, boat never gets enough power to get out of the hole even at WOT. At WOT and 1800 RPMs it feels like it starving for gas and jerking. I hit the choke but it bogs down even more or no change at all. I checked the bulb at time problem starts and its not as hard as I think it should be but it does not collapse.<br /><br />Things I did right before problem started.....<br /><br />changed spark plugs<br />sprayed carbs<br />filled gas tank<br /><br />Things I tried after problem started....<br /><br />drained gas tank and refilled<br />Mercury Quickleen (in gas tank)<br />Mercury TuneUp (sprayed in carb)<br />checked for leaks in hoses<br />changed spark plugs again<br />replaced gas hose and bulb<br />Replaced fuel filter<br /><br />I'm leaning towards a carb rebuild. Should I attempt this on my own? Is there anything else I can check myself?<br /> <br />I tried putting the old spark plugs back in and now it runs about 30 MPH but very sluggish. As soon as I put the new plugs in, I cant even get 2 MPH. I exchanged the new plugs for another set and same thing happens.

 

[sho305]

Re: low RPMs at WOT

Does it idle ok? Did you get the wires back on right? Right plugs? You may have fouled out plugs, indicating rich problem or weak ignition. Think I would pull wires to see what cylinders are dead, or if it is a gas problem. Check the spark with a $5 tester. Get muffs to run in your driveway.<br /><br />Chck plugs to see if they are dry/wet/water. Try squirting gas in carb to see if it starts running. Unlikely to be a carb problem after running all season, but maybe. My old '73 you can take plugs out of carbs and spray all the passages in there on the motor. Could check compression I guess. Also check reeds.

 

[rickdb1boat]

Re: low RPMs at WOT

Does it have a built-in Tank? If so, try running it on a 6 Gallon portable. Put new plugs in first, again! And check out what "sho305" said to try. Thinking you may have gotton some bad gas. Even a little Water will make it run like S*** or not at all. And I do mean "A Little" Water! Do you have a Fuel/Water seperator? If so, check that as well and replace element. The reason I say all of this is that I had similar problems after getting some Water in the Tank. Would die on the Lake, I'd put new plugs in and it would run, not well, but would run for a while before crapping out again. Worth a shot to try a different Tank for a while!<br /><br />EDIT: Definitly check compression first, as suggested!<br /><br />EDIT AGAIN: If it is a Built-in Tank, check Vent and anti-syphon Valve at the Tank.

 

[87Stratos]

Re: low RPMs at WOT

Well I gave in and took the problem to my local boat shop. Turns out the problem was a bad stator and diaphram. It will be 6 months before I get it back in the water to test it but he is confident it will work.