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Charles
Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3937
Experience:  US Navy (Ret) Certified Mercury Marine Tech with over a decade of repair experience.
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Having trouble with 1989 force 85 HP. maybe fuel/air mixture

Customer Question

Having trouble with 1989 force 85 HP. maybe fuel/air mixture adjustment. Also lots of oil sludge after idling a while. Just checked lower unit it is full of oil and no water in oil.
Submitted: 2 years ago.
Category: Boat
Expert:  Charles replied 2 years ago.
Hello, my name is***** you for allowing me to assist you today.
Would you please post the serial number of the engine?
What did you get for compression numbers?
How did the old plugs look?
Customer: replied 2 years ago.
Serial # *****
I don't have my note on the compression I believe it was 123psi with a variation of 2 or 3 psi. This is after I replaced the
cyl head and gasket.Just looked at spark plugs they all looked black and pretty wet with fuel. Did not seem to have water on them.Thank you Charles for working with me on this.
Expert:  Charles replied 2 years ago.
Your welcome,
Compresion seems good.
Has the motor been sitting?
Did you look at the new plugs or the old plugs?
What does the sludge smell like that comes out of the engine?
Customer: replied 2 years ago.
I did not replace the spark plugs. I just pulled them out to look at what was going on in the engine.The motor has been sitting I have been working on it for a few months. It sat for 3 years before that.The sludge is gray, Not real strong smell. Seems to have a gas smell to it.Also the motor seems to consume a lot of fuel. I am running off of a bottle and it uses 1/2 gallon with idling about 10 minutes.
Customer: replied 2 years ago.
I am not sure about the procedure for adjusting idle mixture. Can you please provide this for me.
Expert:  Charles replied 2 years ago.
Can you remove the air box from the carbs, then use the primer bulb and see if the carbs are leaking any fuel into the centers?
Customer: replied 2 years ago.
OK, i took off the air box, pumped the primer bulb and there is not gas leaking into the center of the carbs. nor out the holes on either side of the carbs.
Expert:  Charles replied 2 years ago.
Ok,
Can you pull the fuel pump from the side of the engine, do the same thing with the primer bulb, see if you get fuel from the back or the hose on the front of it.
Customer: replied 2 years ago.
I am not sure I understand your instructions. Here is what I did. I removed the fuel pump by removing the screw holding the filter screen to gain access to fuel pump screw. I removed the four screws holding the fuel pump to the engine. I reattached the fuel filter. I discovered that without the four screws the fuel pump would leak fuel out the side when pumping the bulb. I put nuts on the back of the fuel pump so I could tighten the 4 screws to hold the pump together without being attached to the side of the motor.Now when I pump the bulb, I do not get pressure. I do hear noise through the back hole on the fuel pump. I tried holding my finger over the hole while pumping the bulb. This made the noise go away but did not allow the bulb to develop pressure or pump fuel.
Expert:  Charles replied 2 years ago.
Ok,
This is what I am thinking, you have failed diaphragms in the fuel pump. That is along with possibly a restricted fuel line and a carb that is flooding.
You are going to need to rebuild the fuel pump and he carb, along with replacing the fuel filter and the hose leading to the engine.
Does all of this make sense?
Customer: replied 2 years ago.
Yes this does make sense. Unfortunately over the last few months I have replaced the fuel pump diagram all the fuel lines. This includes the one from the fuel tank to the fuel pump, from the fuel pump to the carbs. I installed an aftermarket fuel filter inline just after the fuel pump. I also replaced the fuel lines between the carbs. I have rebuilt the carbs. I also had to go back into the carbs because of fuel contamination in the tank. Currently I am running off of a bottle of non-ethanol fuel.I am not sure what you were looking for when you said: "see if you get fuel from the back or the hose on the front of it." Was this just to check to see if the fuel pump diaphragm was bad or is there something else that could be wrong in that area?
Expert:  Charles replied 2 years ago.
That was a check of the diaphragms. If you are going thru that much fuel is so little time and the plugs are wet, there is still an issue in the carbs, either the floats are full of fuel or they are not set correctly.
Have you also replaced the needles?
Customer: replied 2 years ago.
Yes I did replace the needles. The kits did not come with seats. I am not especially good with carbs. I have had a lot of trouble after the first time with trash getting into the carbs. This would show itself by flooding and fuel coming out of the holes on the side of the carbs. I am not seeing that now. I have had to clean the bowls and needle and seats multiple times. I have adjusted the floats by eye. I do not have a manual with the specs or directions. I am turning the carb upside down and checking that the float is level. If you have instructions on the carb rebuild, specs, how to adjust float, set mixture, this might be helpful. I bought a set of carbs on ebay. I haven't disassembled them yet to see if they are clean. Nor tried to install them. They came out a 1990 90 hp US Marine Outboard motor was told this may fit 80 hp to 150 hp. They look the same except they have an extra adjustment screw. Not sure what the extra adjustment is for yet.Are you sure that this would have to be a carb problem?
Expert:  Charles replied 2 years ago.
Is the debris in the carbs black?
Customer: replied 2 years ago.
Here is a picture I took one time back in February. There was water in the fuel. I had drained and swabbed the tank but maybe did not get it all the way cleaned. I have since removed the tank and gave it a more thorough cleaning. I believe I had the inline filter on at the time. The last time I took a carb off after it was flooding I believe I only saw light colored debris.What would black debris mean to you?
Expert:  Charles replied 2 years ago.
The dark specs in there are the inside of fuel lines. You have replaced all of them since this pic correct?
How many turns do you have the mixture screws out at the time?
Customer: replied 2 years ago.
I believe that is correct this must have been before I replaced the lines. There is no fuel line between the carbs and the tank/bottle that is not new. I even flushed the new ones out after a while.
Expert:  Charles replied 2 years ago.
Ok,
What about the mixture screws?
Customer: replied 2 years ago.
Did you have any instructions on carb overhaul's specs or setting the mixture for this type of carb?
Expert:  Charles replied 2 years ago.
Carb needles need to be at 2 1/2 turns from a light seat on your boat.
These carbs are pretty simple to work on, to check the float height, you turn the carb upside down and make sure that the float is level.
Customer: replied 2 years ago.
Okay, sounds like the floats are right. You said the neadles need to be at 2 1/2 turns. I believe you are talking about the mixture screws. If I put them at 2 1/2 turns instead of 1 turn will this make it run richer, allowing more fuel in the mix?
Expert:  Charles replied 2 years ago.
Opening the mixture screws will allow more air into the mix, causing the to run leaner, The mixture screws are adjusted when the engine is normally idling, if you sped the engine up and it lean sneezes or pops, you need to adjust the needles slightly. The book says to get the engine to a reasonably smooth idle. That is some times hard to do on a 2 carb 4 cylinder.
Customer: replied 2 years ago.
This is a 3 cylinder 3 carb engine. This about the mixture screws was very important. I thought it was the other way. I thought it was opening up to alow more fuel not air. I am looking forward to trying it knowing this and starting at 2 and 1/2 turns. It may be a couple days before I have time to try it.
Expert:  Charles replied 2 years ago.
No worries,
I was thinking of another engine that I am also working on here. Adjustment is still the same. Let me know what you find out.
Customer: replied 2 years ago.
I tried adjusting the mixture screws to 2 1/2 turns. It ran but the idle speed was too low and would not adjust up with the idle set screw. I also noticed that the fast idle lever made very little difference.
Expert:  Charles replied 2 years ago.
Mike when you raised the fast idle lever, did the actual throttle move?