Need help with Force 40hp...

[dennyjd]

First of all just want to say that this a GREAT site with lots and lots of usefull information for newbies like me!!!!<br /><br />Ok, here's the story...<br /><br />Bought a used 1993 or 94 40HP force for my 16' aluminum bass boat. Finally got the chance to run it yesterday on the lake for the first time. The lake I was in has a no wake only for the first couple miles. Motor started first turn and putted along perfect. Got past the no wake area and opened it up!! Ran perfect. Pushed the boat 29/30mph with a good 14psi of water pressure. We ran it for a good 25 min or so then stopped and fished for about 2 hours. Started it back up, pushed wide open and it didn't have the same power. Only put us up to about 19mph and had about 5 psi less water pressure. It sounded a litte sick too. At half throttle it would "hunt" rpm's. Slowly rise then go back down, then back up. We ran that way for a few minutes then decided to fish some more. On the way back to the boat ramp, we ran out of gas, yes, we were those guys floating aimlessly in the middle of the lake holding up the big red gas can We didn't think to check the 6 gal tank after about 35 min of running. Thought it would run a bit longer then that on a full tank. Got it filled then fired up again. This time it sounded like it was running on one cylinder. Only pushed us about 10mph and at about 6 psi on the gauge. You could hear the other cylinder firing every once in awhile giving a brief shot of power. Eventually we made it back to the ramp and burned up more then half a tank doing so on a short trip!!! The spark plugs are new and I was told that the carb has been cleaned. The motor has very low hours on it. Any suggestions would be helpful. Sorry for the long post!!!

 

[jasonbailey]

Re: Need help with Force 40hp...

Couple of things, come to mind. Please take no offense if these sound like very basic questions. Was the vent open on the gas can? fuel mixed properly? Have you done any of the yearly/seasonal maintenance to it? Chance the fuel pump diaphram? From what I've seen/read, cleaning the carbs don't usually do the trick. Usually a rebuild is in order. Also do you have spark to the one cylinder that is not running, after the motor warms up? 6 gallons in 35 minutes, seems a little much.

 

[dennyjd]

Re: Need help with Force 40hp...

No offense taken at all!! I just appreciate your reply!!! I haven't done any maintenance to it yet. I just got it a few months ago and finally put it on the boat. The marine shop I got if from said it is ready to go. He said he put a new pump on it, cleaned the carb, and a few other things. I will be getting in touch with him but I wanted to start here because I'd like to just take care of it myself if its something simple. I'd also like to have it running well for this weekend. I have gotten into a few other outboards before so I do know a "little" about them. I will check the fuel pump diaphram. Vent was open (cap unscrewed a bit)and I did mix it 50:1 with some synthetic marine oil. I will be checking the spark this week. Yea, it was really sucking down the gas!!!! Seem to run worse after it was shut off and sitting for a bit... Thanks!

 

[roscoe]

Re: Need help with Force 40hp...

2 things I would check first.<br />1 - replace the fuel pump diaphram. I bet it has a hole in it.<br />It then leaks gas into the powerhead and causes an extremely rich (flooded) condition, fouling out bottom plug. Often it will flood so bad the motor won't start.<br /><br />2 - Check for spark on both cylinders<br /><br />6 gal of gas should run that motor for almost 2 hours <br />at WOT ( wide open throttle)<br /><br />Let us know what you find.

 

[luvsfishing]

Re: Need help with Force 40hp...

A friend and I just finished trouble shooting a Force motor that was behaving strangely. It is a long story and I will save it for new posting. The final thing we discovered that was keeping it from running well in the lake with a load on the motor was no spark in one cylinder. This one was simple to fix. The tachometer wire was touching the engine block, and had melted enough to expose the bare wire. It shares a common connection with one of the coil connections and was grounding out the coil for that cyclinder. A spark check is simple to do. Remove the plug from the head, attach the wire back to it, ground the plug to the block(hold by the boot to avoid a nasty shock), and crank the engine. If you don't see blue spark between the two electrodes on the plug, then you aren't getting any spark to that cyclinder, and hence the loss of power. I ran my boat on one cyclinder messing around with all sorts of things, and yes I did burn about a half a tank in about 30 minutes, since the boat was not on plane and the engine was WOT, and not going fast. This could be a very cheap fix for you. Examine all of your electrical connections under your engine cover, and at your ignition switch, it could be something as simple as a loose wire connection, or a shorted wire like mine. We didn't notice the shorted wire until we pulled the flywheel looking for other electrical trouble, but this wire would have been visible prior to pulling the flywheel. The spark check is the most simple test. While you have your plugs out, see how wet they are. If one is significantly wetter than the other, check the spark on that one first, as that may be the one that isn't firing. Good luck!!!

 

[dennyjd]

Re: Need help with Force 40hp...

Thanks for all the help guys!! I will check these things out very soon and definitely let you know the outcome!!!! Thanks again