1985 USMARINE FORCE 50HP

[nailsetter]

HAVE A 1985 FORCE 50HP MADE BY USMARINE. IT RUNS GREAT. STARTS UP WITH 1/4 TURN. THE PROBLEM IS THERE IS NO POWER. LUCKY IF MOVE THE BOAT 5 TO 10 MPH . I HAVE A 16' FIBERGLASS BOAT.V-HULL. THE PREVIOUS OWNER SAID IT WOULD PULL A SKIER WITH NO PROBLEM.? MOTOR SAT FOR 5 YEARS UNDER COVER. HAD NEW WATER PUMP INSTALLED AND FUEL PUMP REBUILT. RUN GREAT JUST NO POWER. WAS ADVISE TO TAKE A COMPRISSION TEST ON IT. SO I DID. ONE CYLINDER WAS 140 AND THE OTHER WAS 130. WAS TOLD IF WITHIN 10% OF EACH OTHER IT WAS GOOD.? ANY OTHER SUGGUSTION OR ADVICE WOULD BE GREAT. IF IT HELPS MODEL#507F5A SERIAL #2424 THANKS

 

[JB]

Re: 1985 USMARINE FORCE 50HP

Hi, nailsetter.<br /><br />"Runs great just no power" is an oxymoron if I ever saw one.<br /><br />You are running on one cylinder or not opening the throttle plate(s).<br /><br />With the engine at idle, remove (carefully, with insulated pliers) one spark plug lead at a time. If the engine dies when you pull one and doesn't notice when you pull the other you have a dead cylinder. If both just cause a reduction in idle speed then you aren't opening the throttle butterfly.<br /><br />A dead cylinder has: no spark, no fuel/air mix or no scavenging (bad reeds).<br /><br />Good luck, and let us know what you find. <br /><br />Oh, and also lose the all capitals. You seem to be SHOUTING.

 

[roscoe]

Re: 1985 USMARINE FORCE 50HP

If the motor "runs great", you may want to check for a spun hub on the propeller.<br /><br />A spun prop is...<br />Ok, a prop is made of two parts. The round cylinder with the blades attached, and the part inside the cylinder. The two parts are held together by a piece or rubber which is pressed between the two parts.<br /><br />When the prop strikes a hard object like a rock, the rubber "hub" is supposed to slip, to prevent severe damage to the lower unit and engine. When the rubber gets older, it can slip from just the force applied by the engine. Usually a spun prop will work at slow engine speeds, but begins to slip as the engine speeds up. Then it will slip completely and the engine will rev faster.<br /><br />You can check the prop by scribing or painting a line on the prop, from the center, across the rubber, onto the outside. Take the boat for a test run, make sure to accellerate hard, a few times. Then look at the line you created. If it is still a straight/continuous line, the prop is ok. If the line is broken, the prop hub is spun.

 

[12Footer]

Re: 1985 USMARINE FORCE 50HP

Roscoe is allmost surely correct here. And this particular motor is notoriously rough on thier prop hubs. The owner of a pre-1993 Model Force 50HP, is well-advised to purchase and carry a spare prop, prop nut (in case you drop the originals in 1000ft of water), and spare cotter and retainer pins.<br />They can pull a skier up on a light 16footer, but I would not recommend it. The very act of the required "hole-shot" is all it takes to spin-out the hub on this particular unit. The skipper should apply throttle gradually on the 50HP.<br />A prop shop can re-hub them tho, for under 40bucks, so don't toss the original prop. Have it rebuilt.

 

[nailsetter]

Re: 1985 USMARINE FORCE 50HP

Sorry about the caps.Did not think it meant that i way yelling. Thank for all the advice and will check it out. Sounds like there is hope yet. Well surely check the spun prop idea. Thanks again and will let ya know what happens

 

[nailsetter]

Re: 1985 USMARINE FORCE 50HP

Oh will also check the spark too. Thanks

 

[nailsetter]

Re: 1985 USMARINE FORCE 50HP

Well did the spark test pull one wire at a time and notice a reduction of idle speed.But found another problem throttle cables are crack and worn and kink up when trying to increase speed. Guess i will have to invest in some new cables next before going for a prop. Is there a universal set of cables i can get to fit the control i have now.If so where can i find them. thanks again.Also the one on the boat seem long how would i measure for new ones

 

[nailsetter]

Re: 1985 USMARINE FORCE 50HP

Oh i have a single lever side control box or unit what ever ya call them

 

[roscoe]

Re: 1985 USMARINE FORCE 50HP

Cables have to be a little longer than what you may think.<br />They are also only sold in foot increments, better a little too long, than 2" too short.<br /><br />If the cable ends look like the one in this link, you have found it, if not, search the megamall for throotle cables.<br /><br /> http://www.iboats.com/mall/index.cgi?prod_id=22162&current_category=throttle cable&*******=347013029