force 125hp w/ no output

[cdfran]

So I previously posted a thread about my force bogging out and got a lot of help, unfortunately none of it panned out. I really need some help, I am fairly good with my hands but have little tech. knowledge, especially about marine engines, and if I have to take this to a mech. I may not be able to put this boat on the water this season. It is an early 80's force 125 hp outboard, the compression has been checked and is good, as is the propeller hub. When it gets in the water it idles well and moves slowly without much trouble, however when I throttle up, the carbs are open wide and there is good fuel flow into the carbs. All of the plugs have strong spark and the engine doesn't have any rattles that I can hear. I do think the lower unit is leaking a little as I have seen oil coming out the water output and the screw on the front of the lower unit (not the fill or the vent but the one everyone says not to mess with?) and when I changed the oil in it there was something that might have been water. I really dont know what else to look for, I have an engine manuel but there isnt any trouble shooting section. Please if you have any ideas let me know. Thanks so much.

 

[maxum247]

Re: force 125hp w/ no output

How did you verify the prop wasn't slipping?
When changing the lower unit oil did you see any metal flake in the oil?

 

[cdfran]

Re: force 125hp w/ no output

verified that it wasnt slipping using the marker line test while i was at the lake this weekend. Did not notice any metal flakes but had never seen what water does when leaking in, so was more preoccupied with that and could have missed it, but dont think so. What are you thinking?

 

[pnwboat]

Re: force 125hp w/ no output

Do you have a tach? If so, what RPM are you turning. Should be around 5000. If not, sounds like a fuel supply problem even though you mentioned it was checked. A bad on-way valve in the primer bulb can cause this. A collapsed primer bulb when going to full throttle is an indication of this problem. Also clogged fuel line/tank.

It you are turning 5000 or so RPM it sounds like something in your lower unit since you checked the prop HUB. Althiugh it kind of sounds like a spun HUB if you're turning 5000 RPM.

Don't know if this will work but you might give it a try. Disconnect the battery and take the plug wires off the plugs. Don't want to accidentaly start the engine with the next steps. Push the throttle all the way forward to engage the gears in the lower unit. Take the engine cover off so you can see the flywheel. Turn the propeller with a socket and ratchet on the propeller nut. You should see the flywheel turn. Not sure if you can tell if there is any slippage.

Again, be sure to disconnect the battery and plug wires. This engine will run without a battery if you get it spinning fast enough. Not likely, but I would imagine you would want to do anything necessary to keep your hands and fingers intact!

If you can tell that there is slippage between the prop shaft and the flywheel, then the problem has to be in the lower unit itself. If no slippage, then it has to be in the prop HUB.

 

[jerryjerry05]

Re: force 125hp w/ no output

What RPM's at WOT ? If the motor revs and the boat moves but no speed. Try another prop.Jerry

 

[cdfran]

Re: force 125hp w/ no output

I dont have a tachometer on this boat, the dash was redone by the previous owner.

 

[Haywood123]

Re: force 125hp w/ no output

do you have a portable gas tank? Twice now, once with my Force and once with my old Merc, I had problems I couldn't solve and I switched to a different fuel source and the problem was solve.
With you lower unit, if you were getting water in it, you should be able to tell if you check the oil out right after it comes our of the water. It should be milky/frothy. rather than oil like.

 

[cdfran]

Re: force 125hp w/ no output

Yeah the lower unit is definately leaking, and I am having it resealed, but with the separate fuel source, do you have to change tanks or is changing the fuel enough? I have been through at least three full tanks of fuel after emptying and throwing out what was in it.

 

[Haywood123]

Re: force 125hp w/ no output

I always switched to a portable tank, cause I didn't feel like draining the big tank if it wasn't the problem.

 

[cdfran]

Re: force 125hp w/ no output

I have changed out the fuel, and run through a few gallons so i am fairly sure that the fuel is not a problem, I also dont think that fuel flow is a problem. Didnt mention this earlier cause it is kind of hard to describe, but when the boat is on the water, the throttle is wide open and I am having the no output problem, if I turn sharply then the boat will surge for just a second. It doesnt last long but it will happen intermittenly. If anyone has anymore idea's I am willing to try, and appreciate the help.

 

[Frank Acampora]

Re: force 125hp w/ no output

When you turn sharply, you ventilate the prop (sometimes, depending on boat speed, attitude, load, and wave conditions) and reduce the load on the engine. It will pick up speed (RPM) until the prop locks up into the water again. Since the load is reduced, it takes less power and thus less fuel for the engine to turn higher RPM.

SO you are not having an electrical problem. That only leaves fuel and air.

SO: Start right at the tank. if you have a quick-connect fitting, remove the male end and clean the hole in the threaded end. Crap gets behind the spring and ball. Replace the fuel pump diaphragm and gasket--cheap preventive maintenance--. Remove the black plastic fuel inlet and check the screen. It doesn't take much to restrict fuel flow to a thirsty 125.

I think you mentioned using several brands of fuel. Take off the carb bowls and look for a gritty or jelly like substance. Since gas companies started switching to ethanol, some brands react and cause this jell (when it dries, it looks like sand)--really can mess up the fuel system. If you do find this in the bowls, remove the carbs and clean them totally. also clean fuel filters, fittings, and tank strainers.

AIR: Of course, if you have a broken reed petal or two, the engine will still run, and may even idle fairly well, but not produce its full power. So, while you have the carbs off, look into the manifolds and check that all reed petals are present. (depending upon model, either 8 or 10 per cylinder.) Vee blocks are staggered, one slightly higher than the other. Each vee block serves one cylinder.)