NEWBIE ON BOATS force 70hp runs rough and boggs down or out

[hjlanda22]

Ok we checked comperission with a cold motor <br />1- 110<br />2- 114<br />3- 115<br /><br />its a 1994 Force 70hp engine on a 16ft 94 bayliner. I thought that those numbers were low....... am I wrong? is this where it is supposed to be? is there something I can do to bring it up?<br /><br />We were out on a lake and it ran fine then we towed a ski'r still ran fine, then we towed 2 ski'rs there was no power and eventually bogged out and just before it bogged out it actual went full force and then bogged back down and the up and finally out...... Eventhough we stoped towing (with no load) this still continued a couple days later we went to test it out agian and STILL did the same thing..... ANY COMMENTS would help<br />THANKS!!!!

 

[Oldsaltydog]

Re: NEWBIE ON BOATS force 70hp runs rough and boggs down or out

The compression seems a bit on the low side, but it should be taken with the motor warm. Decarboning may help you -- you could check the SEARCH for details. Sounds like you may have a fuel problem -- how is the gas tank air intake, the fuel filter, the fuel pump output, and are the carburators clean? How are the spark plugs?

 

[roscoe]

Re: NEWBIE ON BOATS force 70hp runs rough and boggs down or out

Sure sounds like a fuel or carb related surging problem.<br /><br />You may also need to switch to a different prop to pull 2 skiers.<br /><br />What are your wide open throttle rpm's when you are not pulling a skier?

 

[hjlanda22]

Re: NEWBIE ON BOATS force 70hp runs rough and boggs down or out

I dont know the rpms this boat does not have a gauge for that...... Also I am getting a carb kit on friday due to rebuild it on sat along with replacing the fuel pump diaphram I heard about de-carbing Ive heard it does GREAT for my symptoms. plugs are new but when we pulled them they were very dirty with what appered to be black stuff almost like oil.... fuel filter is new. I was thinking it had to do with the gas you 2 just comfirmed it more for me..... with the comperssion readings I was just hoping that the engine was ok..... does it sound like the engine could be bad.....???? or does it sound more like carbon build up and time to rebuild the carb and fuel pump??? (which I am going to do on SATERDAY.....) Thanks for your response I REALLY appreciate it.......

 

[hjlanda22]

Re: NEWBIE ON BOATS force 70hp runs rough and boggs down or out

Ebg<br /><br />the gas tank is supposed to take in air????? would it not leak then???<br /><br />I dont know what the fuel pump it doing thats why I am just going to go ahead and rebuild it as well just to be sure.......

 

[Oldsaltydog]

Re: NEWBIE ON BOATS force 70hp runs rough and boggs down or out

Yes, fuel tanks have air inlets at their top walls, at the end of a hose, which is sometimes combined with the gas filler unit. If it is blocked, the fuel has a hard time flowing out. Think of a straw filled with fluid and plugged at the top with a finger. When the finger is taken off, the fluid runs out. In general, your motor sounds okay, but it seems to need the type of work you are planning to do. Good luck.