Re: 1989 force 125hp help
Well, Roquebert--let me chime in here. When diagnosing engine problems we really need to slow down and analyse what we know and do not know about the engine.
First, since you say the engine starts easily and seems to run well until you try full throttle, let us assume for now that it is not an ignition problem. Since the ignition system is the most complex and most difficult to diagnose, just for now, let's forget about it.
There are basically only three systems in the engine:
1. Fuel
2. Air
3. Electrical/ignition.
If an engine has the proper amount of air and fuel ignited at the correct time, It must start and run well.
Fuel system would be everything from the tank until the fuel is vaporised in the carburetor.
Air induction system would be the carb butterflies and reed valves (reeds)
Ignition would encompass triggers, stator, CD boxes and coils, timing linkage, and spark plugs.
Now: you said you tested the boat twice with no problems before you bought it, then let it set for a while and now you have problems getting adequate horsepower. So: let's figure out what could have happened in between. Let's start with the fuel system.
First off, take off the spit-back covers, open the throttle to maximum and look to see that the carb butterflies are opening fully. They should be horizontal or nearly so. If they are only opening say 1/2 way, then the linkage is either jamming or slipped. Also, look at the top of the linkage and check to be sure that one of the plastic fittings has not broken, keeping timing from advancing. I know! I said we will leave ignition for later but this is so easy to check, you might as well.
You also said you started with an empty tank and put in some fuel mixed in the correct ratio. You also stated that each time you tried to use the boat, you added more. If it's a Bayliner, it probably has a built in gas tank. There will probably NOT be a strainer inside the tank so we can eliminate a clog there. Now: in the past, I have explained that the combination of different brands of gasoline in a boat tank could cause a gelling problem (and not the good kind like Dr. Scholl's. This is one time you don't want to be Gellin like Magellin.) So if you have used different brands of gasoline, you need to check the entire fuel system from tank to carbs for evidence of this sediment which can clog carbs and filters or strainers. If you have a quick-connect fitting on the tank end of the fuel line, remove the male end and check behind the ball for crud and junk. One of the things you can easily do is to remove the fuel line at the engine and put it into a suitable container. Pump the priming bulb and see if you get a good flow with each squeeze. If so, then we have eliminated everything up to the engine. Next remove the black plastic fuel line fitting on the fuel pump. Look at the enclosed screen. Is it Clean? Yes, then that's not the problem.
You said that the primer bulb does not get hard and one carb leaks. Remove the fuel bowls from the carbs (big brass nut on the bottom) Are the fuel bowls clean? If so carbs are most likely OK. If they have sediment, then our suspicions are raised. If they have so much gel or sediment that the float was held down, then there is your most likely culprit. Carb is flooding and the two cylinders it services are flooding, reducing horsepower. Remove the carbs and thoroughly clean them. Check closely to be sure that inlet needles and seats are clean and not damaged. While the carbs are off, look in the manifold and see if any reed petals are broken off. If there are broken reeds, the manifold needs to be removed and the reeds replaced.
Next let's go back to the fuel pump. The top half is held to the bypass cover by six screws. Remove the screws and pop off the top half. The diaphragm and gasket are located between the halves. Is the diaphragm hard and wrinkled? hold it up to the light. Do you see pin holes? Is it actually cracked or disintegrating? No matter what, replace it and the gasket anyway--It's cheap--3 bucks for the diaphragm and 2-3 bucks for the gasket. Proper order is gasket, diaphragm, then top half of pump. Visually check the three button valves in the top half to be sure they are not being held open by debris and are not damaged. While you are at it, buy a cheap 3 dollar plastic auto fuel filter and put it in the fuel line BETWEEN the fuel pump and carbs. Gheck the short length of hose running to the smaller second stage of the fuel pump. If this hose is cracked, leaking, disconnected, or broken, the pump will not work at its full efficiency. This is for the old style Force pump. The Mercury pump is square and does not have the second stage hose but it does have diaphragms and rubber/composite valves. When you remove and disassemble it, it will be obvious if something is broken.
So now we have examined the complete fuel system and air induction, and eliminated any problems. If the engine problem was fuel related, then it should perform rather well now. The reading of 115 on one cylinder is a little low but it should not cause the degree of power loss you see.
When you have completed all the checks, see if the problem has been solved. If not come back and we will try to diagnose the ignition systen
