98 mercury force 120 carb leaking

[philliph]

This one has the tillotson 854451 carbs. It's a 98 model on a procraft bass170.

My issue is that it is not starting well and not full speed when I get it fired up

I've replaced the gaskets and cleaned the pin and needles and as far as I can see they won't get any cleaner. I just put it all back together and when I squeeze the bulb fuel shoots out of the side if the carb and through the air cover on the front of it. Now I'm no genius but it sounds like I still have a pin, float ,or needle issue. It's
Now starting well but fuel spits out everywhere and leaks down on the bottom carb.

Is there a setting
For the float I've missed? I can't see anything that would lead me to believe the pin or needle have any gunk on them. Any other suggestions ?

 

[philliph]

Re: 98 mercury force 120 carb leaking

Also. I'm
Not sure what the valve on the side if it is that allows me to adjust the fuel ratio is called but I have it at two and a half turns to the left from seated. It doesn't seem to have any impact on the fuel spitting out of the side of the carb if I adjust it either way

 

[pnwboat]

Re: 98 mercury force 120 carb leaking

Float level is probably not set correctly. It's set too high. Are you familiar with setting the float height?

That would be the air mixture screw. It should be anywhere from 1 to 1 1/2 turns out from lightly seated.

 

[philliph]

Re: 98 mercury force 120 carb leaking

I may have figured it out. The engine was not level. I assume the float was open because of this. Anything else I should look for ??

 

[philliph]

Re: 98 mercury force 120 carb leaking

I turned to 1.5 turns and it appears to be idling fine. I put the muffs on it and throttled it as well. I guess at some point I'll buy new pins and needles for the carbs. I heard that if I get stuck on the lake to hit the fuel bowl with a screw driver to loosen up a stuck needle. I guess I'll do that if it comes
Down to it

 

[philliph]

Re: 98 mercury force 120 carb leaking

Also. No idea how to set float level.

 

[pnwboat]

Re: 98 mercury force 120 carb leaking

You have to remove the carburetor to do set the float height. Remove the fuel bowl, turn the carburetor upside down and the float should set just as in the diagram. To adjust the height, you bend the tab that pushes against the needle valve. Don't adjust the height by pushing on the float because it may damage the rubber tip on the needle valve. That is if the needle valve has a rubber tip. Some are just metal.

 

[philliph]

Re: 98 mercury force 120 carb leaking

Well I'm back at square one. Yesterday I adjusted the float so it is parallel to the casting. Everything appears to be in good shape but the top carb still leaks gas all over the place. The boat will run but it appears that only one carb is actually working. I can't get above 5mph. I'm at my wits end. What's next. Do I need to give up and take it to a repair service ?

 

[pnwboat]

Re: 98 mercury force 120 carb leaking

You could take it in for repair however, I think you'll be pretty amazed at how much it'll cost you.

Sounds like you might have a bad needle valve, or a bit of debris that is stuck between the tip of the needle valve and the seat. You should also install an in line fuel filter between the fuel pump and carburetors. While you're at it, you might do a compression check and make sure you have spark on all four cylinders.

 

[jerryjerry05]

Re: 98 mercury force 120 carb leaking

Get ANY kind of manual.
Any one is better than none.
Do a compression/spark test(just in case).
Install a small particle filter before the fuel pump.
I believe the 98 came standard with a filter(useless) between the carb/pump.
Take your time in cleaning.
Look at the needle and see if the tip has deformed?
The needle is it rubber tipped? Or solid?
Solid: look at the seat and see if the o-ring/seal in the seat is deformed or missing?
Rubber tip: see if it's smooth and no grooves.
Reset the float level and drop.
Post the results of the compression test.
Fill out the profile, location. You might be close to someone who can help??

 

[Jiggz]

Re: 98 mercury force 120 carb leaking

Personally, I would recommend dismounting the affected carb, disassemble the bowl but do not disassemble the float unit yet. Take good pics with the carb set upright and also inverted focusing on the float and the needle valve. Technically, in the inverted position, the float should be level with the carb casting and the needle valve close. You can check this by blowing through the fuel inlet connector and no air should go through the needle valve or at least there should be a very good resistance. In the upright position, the float should drop down with its lowest point even with the pick up tube (center post) and should not be touching the center post or pick up tube. Post pics and it will make the repair at lot easier for all.

 

[philliph]

Re: 98 mercury force 120 carb leaking

to everyone here providing input I greatly appreciate it. So today when I took the carburetor off I noticed that a couple of the Reed valves were broken. Ended up un assembling and machining two new sets of valves from a 28 gauge sheet-metal I had. Now after I have it all put together everything is firing up and looking great. I didn't notice though while running it with the muffs that I had one occasion to where fuel started spitting out of the carb like it did before. I tapped the fuel bowl with a wrench and it stopped. Sound like I should replace that needle?

Overall I'm
Better than where I started so progress is being made. I'm going to out it on the water in the morning to see what it will do. If
I knew how to most pics from photo bucket I Would do so

 

[pnwboat]

Re: 98 mercury force 120 carb leaking

Well at least you've got it figured out. Seems like the 1996 - 1998 120HP motors are rough on the reed valves or the material they make them out of is not strong enough. Only broken reed valves that I've ever seen are in those motors. Sent you a Private Message.

 

[Jiggz]

Re: 98 mercury force 120 carb leaking

If the tapping on the other carbs continue to keep it from flooding, it also deserves to be dismounted and carefully inspected. With your new knowledge of troubleshooting carbs, this should be an easy "walk in the park" for you. Good on you and congrats.