1998 Force 90hp motor flooding need HELP

[michelob77]

Ok yall I have been reading on this site for awhile but just now signing up. This is going to be a little long but want to give as much info as i can.

I have a 1998 90hp Force. I bought the motor back in July that was on the back of a pontoon boat I decided to buy and redo. Prior to me buying the motor it had been sitting for about a year. When I got it I cleaned gas tank, replaced fuel lines, new fuel filter, spark plugs, cleaned carbs, replaced the needles, new water pump impeller and thermostat.

The problem I am having is right now the middle carb seems to be flooding the motor, it is coming out the exhaust when trying to crank and front of carb. I have taken these carbs apart numerous times cleaning them. I finally broke down and took it up to a boat shop a few weeks ago and all they did was clean all 3 carbs some more and put another inline filter under the cowl. When I got it back it was running good and had it out on the lake a few times in the past couple of weeks and it ran just fine with full power.

This past sunday I took it out and tried to crank it when I got to the ramp and it never started just flooded. Brought home and saw that the middle carb is flooding again. Took them apart again and cleaned and put back on the boat and still flooding so I dont know what may be wrong. I am about to order a new float for the middle carb and a fuel pump diaphram kit just to replace it. I have taken the cover off the fuel pump before and it looked pretty good.

Maybe someone on this site can give me some info to try. Is there anywhere that I can just buy a new carb cause I havnt found one available anywhere.

I read where my center and bottom carbs are supposed to be the same is this true? Cause my middle is different.
The part numbers on my Tillotsen carbs are as follows:
Top 854449
Center 828308
Bottom 854450

Thanks
If you need anymore info on the motor just let me know and I will post it.

 

[pnwboat]

Re: 1998 Force 90hp motor flooding need HELP

If you squeeze the primer bulb 4 or 5 times and it gets good and firm, and no leaks from the carbs, the needle valves are sealing OK.

Do your floats have the metal tab that pushes on the needle valve, or is it plastic? If it's metal, then you can bend it to adjust the float level to fine tune it. I had a similar problem with the all plastic floats. Found some used plastic floats with the metal tabs and solved my flooding problems. Attached is a picture of the plastic float w/metal tab.

One other thing to check is the reed valves. If the reed valves are broken, you may see the motor spitting fuel out of the mouth of the carb. when you try and start it.

 

[michelob77]

Re: 1998 Force 90hp motor flooding need HELP

Do your floats have the metal tab that pushes on the needle valve, or is it plastic? If it's metal, then you can bend it to adjust the float level to fine tune it. I had a similar problem with the all plastic floats. Found some used plastic floats with the metal tabs and solved my flooding problems. Attached is a picture of the plastic float w/metal tab.

Yep mine has the metal tabs and I just took them apart and was about to bend the middle carbs tab some. I guess we are on the same page so far any other tips would be great.

Also mine has the pressed in needle seats so just changing the seat is I guess out of the question if its worn any. You wouldnt think it would be being a 1998 model.

 

[pnwboat]

Re: 1998 Force 90hp motor flooding need HELP

I edited my post after you replied. Sorry about that. To check the needle valves, set the motor level, squeeze the primer bulb 4 or 5 times and look for leaks at the carbs. If no leaks you should be good to go.

If it still spits fuel out of the carbs when you try and start, you might look at the reed valves. Just make sure you're not over choking it. Too much choking will cause fuel to spit out of the carb too.

 

[michelob77]

Re: 1998 Force 90hp motor flooding need HELP

I edited my post after you replied. Sorry about that. To check the needle valves, set the motor level, squeeze the primer bulb 4 or 5 times and look for leaks at the carbs. If no leaks you should be good to go.

If it still spits fuel out of the carbs when you try and start, you might look at the reed valves. Just make sure you're not over choking it. Too much choking will cause fuel to spit out of the carb too.

Well I just got done bending the metal tab on the middle carb where it is slanted up some when it is upside down and also threw in a new needle while i was at it cause i have a few extras. Bolted it back up on the motor and conected everything except for the plastic airbox so I could see. When I pumped the primer bulb up it still just pours out of the middle carb. Didnt even try to start it cause its just flooding anyway.

Do you think maybe the float tab is just so worn than when I pump the bulb it just bends back out? Guess I can take it back apart and look and see if it did.

 

[CharlieB]

Re: 1998 Force 90hp motor flooding need HELP

When looking at the needle and seat, pay close attention to the TIP of the needle, it should be viton, NOT metal, unless it has a removable rubber 'seat' pressed inside the brass seat

Some Merc/Mariner/Force carb kits contain EITHER viton tip needles for use with the pressed in brass seat

or

a steel needle to be used with a RUBBER seat that gets pressed down inside of the brass seat.

You can switch needle types only if you add (or remove) the rubber seat

Do NOT set the float height different than the other carbs as this will change the fuel flow at WOT and can possibly damage that cyl.

 

[pnwboat]

Re: 1998 Force 90hp motor flooding need HELP

I doubt that the tab is worn out and bending when you pump the primer. Look very closely at the needle valve seat itself with a strong light. Make sure it's not damaged. Try cleaning out the passage with some carb cleaner. If you have a can that has the thin plastic extension to get it right down in the needle valve seat area. You may have some debris like some hair or piece of metal or corrosion...something stuck in the seat itself.

 

[michelob77]

Re: 1998 Force 90hp motor flooding need HELP

When looking at the needle and seat, pay close attention to the TIP of the needle, it should be viton, NOT metal, unless it has a removable rubber 'seat' pressed inside the brass seat

Some Merc/Mariner/Force carb kits contain EITHER viton tip needles for use with the pressed in brass seat

or

a steel needle to be used with a RUBBER seat that gets pressed down inside of the brass seat.

You can switch needle types only if you add (or remove) the rubber seat

Do NOT set the float height different than the other carbs as this will change the fuel flow at WOT and can possibly damage that cyl.

The needle itself has a rubber tip. Yep I didnt want to adjust the float any just seeing if it would stop it from flooding but it didnt. A few people are telling me that my middle carb might be the wrong one on there. The middle carb on my motor now is a Tillotsen 828308 and what Im finding is that it should be just like the bottom a 854450. Can anyone help me find out what carb should be on there? Any other tips to try?
Thanks

 

[pnwboat]

Re: 1998 Force 90hp motor flooding need HELP

Also when you have it apart, make sure the float itself pivots up and down freely and is not hanging up on something and preventing it from closing the needle valve.

 

[michelob77]

Re: 1998 Force 90hp motor flooding need HELP

I doubt that the tab is worn out and bending when you pump the primer. Look very closely at the needle valve seat itself with a strong light. Make sure it's not damaged. Try cleaning out the passage with some carb cleaner. If you have a can that has the thin plastic extension to get it right down in the needle valve seat area. You may have some debris like some hair or piece of metal or corrosion...something stuck in the seat itself.

I have cleaned the needle valve seat out several times with carb cleaner and sticking the plastic extension down in there and blasting it. I have also blown air through it after cleaning. Today I also used the tip of a tooth pic to get down in the hole while using carb cleaner and all. Just no luck.

 

[pnwboat]

Re: 1998 Force 90hp motor flooding need HELP

I wonder if the float itself has a crack in it or is no longer buoyant? Is the float a hollow plastic piece or does it look like some type of foam material. The foam types can absorb gas and become less buoyant when they get old.

 

[michelob77]

Re: 1998 Force 90hp motor flooding need HELP

Also when you have it apart, make sure the float itself pivots up and down freely and is not hanging up on something and preventing it from closing the needle valve.

Seems like it is pivoting just fine when takin apart and when I install the bowl back on it I can hear it pivoting just fine inside. Keep the tips coming its got to be something lol

 

[michelob77]

Re: 1998 Force 90hp motor flooding need HELP

I wonder if the float itself has a crack in it or is no longer buoyant? Is the float a hollow plastic piece or does it look like some type of foam material. The foam types can absorb gas and become less buoyant when they get old.

The floats are the hollow plastic ones and they seem to be nice and clear with no 2 stroke mix in them. I have even held them all under water to see if they bubble any and they dont and float fine.

 

[pnwboat]

Re: 1998 Force 90hp motor flooding need HELP

Can you pinpoint exactly where the gas is leaking from the carb?

 

[michelob77]

Re: 1998 Force 90hp motor flooding need HELP

Can you pinpoint exactly where the gas is leaking from the carb?

Since i didnt put the plastic air box thing on this time when I pumped the bulb. It looks to me that it is coming up from the bowl through the nozzle and into the throat of the carb and just pouring out. Hope that made since lol.

Does anyone have any info on if that middle carb is even the right one? Since I have only had it since July I dont know what has been done to it. The guy told me it ran fine over a year ago but I dont know for sure.

 

[pnwboat]

Re: 1998 Force 90hp motor flooding need HELP

If the gas is coming out through the throat of the carb., it has to be due to the needle valve not shutting off the gas supply.

Looking at the parts breakdown....Top carb should be 854449. Center and bottom should be 854450. Looks like someone has changed the middle carb. Could it be that the needle valves you have don't fit the middle carb. ???

 

[CharlieB]

Re: 1998 Force 90hp motor flooding need HELP

Sorry to ask you to do it again, but........

Take the carb off, remove the bowl, invert the carb just as if you are checking the float height, blow into the fuel inlet to feel it leak.

Lift the float to open the needle, air should pass, left go, It should seal off perfectly.

Check the inlet tube, the fuel line, for any foreign object that could be pushing in against the needle.

There has to be a reason, we just haven't found it , yet.

Possibly a crack in the carb body allowing fuel to bypass the seat and into the bowl?

What choke/enrichener system is one there, could it be feeding back into the bowl?

 

[michelob77]

Re: 1998 Force 90hp motor flooding need HELP

If the gas is coming out through the throat of the carb., it has to be due to the needle valve not shutting off the gas supply.

Looking at the parts breakdown....Top carb should be 854449. Center and bottom should be 854450. Looks like someone has changed the middle carb. Could it be that the needle valves you have don't fit the middle carb. ???

Thats what I was noticing on the parts breakdown I should have the 854450 for my center and bottom. I dont I have it as my bottom but my center is a 828308 and I dont know if it should be on there or not and like u said the needle valves might not be right.

 

[pnwboat]

Re: 1998 Force 90hp motor flooding need HELP

Carb P/N 838308 is the top carburetor for a 1996 - 1997 Force mercury 90HP motor. Uses the same needle valve as carbs P/N 854449, 854450 on top and bottom position on your motor.

Try removing or pinching off the fuel enrichment line going the middle carb. when you squeeze the primer bulb.

 

[pnwboat]

Re: 1998 Force 90hp motor flooding need HELP

Make sure the fuel bowl vent is not plugged. Yours may not be in the same position as the picture, but it has to have one. If the vent is plugged, the needle valve will not operate properly due to excessive pressure in the fuel bowl. Usually when the fuel bowl gets too full, the gas will flow out of the vent, not the throat of the carb.

See picture below.