1992 FJ1200 leaking fuel from carbs (pics included)

[MikeC149]

First post, Mike from Philly with a 3,000 mile (4800km) 1992 FJ1200.

Been lurking here for a couple weeks, after getting a new-to-me FJ1200, finally got it running after cleaning the gas tank/replacing filter, changing oil and tires, and cleaning the carbs with a rebuild kit from David on these forums. The bike is so smooth and fast! 

I love it but I noticed today that it appears to be leaking gas (only while running) from the black hose coming off the carb. This hose connects to the White T piece on the left side between carbs 1 and 2. Could this be a float bowl overflow? I've also noticed the fuel gauge reading half a tank after only putting 50 miles on it! This must be incorrect as I'm probably losing gas from the carbs leaking onto the street. 

Could this be a float bowl issue?!? Hoping to do some long Skyline Drive touring on my new FJ! 

-Mike C.

https://photos.app.goo.gl/PcDEHvVQVhzpdRXm7

[Pat Conlon]

Hi Mike, welcome to our forum
The hose you described is called the "fuel bowl vent" hose. There is one vent hose for each pair of carbs. They equalize the air pressures outside and inside the fuel bowls. In addition there are 4 smaller hoses (1) coming of each carb, those are called "choke vent" hoses, they draw air into the choke circuits when the choke is engaged.
When you installed David's carb rebuild kit, did you replace the o rings on your float needle seats?
If not, you need to...if so, did you by chance, damage the o ring when you reinstalled the needle seat?
See #19 below




If you are sure you're ok on that point (it's a common source of leaks) and you are sure your fuel system is clean (no crud between the float needle and seat, holding the needle open) then I would check your float levels.

There are 2 different procedures: 1) Check fuel Level (easy) and 2) Check the float height (harder)

The easiest way is to first check your fuel level in the bowl....this is done with the carbs on the bike using a piece of clear fuel line to see where the fuel level is in relation to the bowl gasket....perhaps one carb has a high fuel level causing the flooding? If the fuel level is too high you will need to remove the carbs, open up the bowls and check your float heights, adjust as necessary.

We have lots of good info. saved over in our Carb Files, take a stroll: https://fjowners.com/index.php?board=21.0

Here's a post specifically on fixing carb leaks: https://fjowners.com/index.php?topic=46.0

Cheers.  Pat

[MikeC149]

Hi Mike, welcome to our forum
The hose you described is called the "fuel bowl vent" hose. There is one vent hose for each pair of carbs. They equalize the air pressures outside and inside the fuel bowls. In addition there are 4 smaller hoses (1) coming of each carb, those are called "choke vent" hoses, they draw air into the choke circuits when the choke is engaged.
When you installed David's carb rebuild kit, did you replace the o rings on your float needle seats?
If not, you need to...if so, did you by chance, damage the o ring when you reinstalled the needle seat?
See #19 below




If you are sure you're ok on that point (it's a common source of leaks) and you are sure your fuel system is clean (no crud between the float needle and seat, holding the needle open) then I would check your float levels.

There are 2 different procedures: 1) Check fuel Level (easy) and 2) Check the float height (harder)

The easiest way is to first check your fuel level in the bowl....this is done with the carbs on the bike using a piece of clear fuel line to see where the fuel level is in relation to the bowl gasket....perhaps one carb has a high fuel level causing the flooding? If the fuel level is too high you will need to remove the carbs, open up the bowls and check your float heights, adjust as necessary.

We have lots of good info. saved over in our Carb Files, take a stroll: https://fjowners.com/index.php?board=21.0

Here's a post specifically on fixing carb leaks: https://fjowners.com/index.php?topic=46.0

Cheers.  Pat

Thank you for the detailed response!
I actually replaced the float needle seat because I wasn't happy with the cleaning I could achieve with the stock one. I did still use the stock float valves (the thing with the pointy rubber tip).

I would like to check the float bowl level with the carbs on the bike, if I can. What do I connect the clear fuel line to? Connect to that white T piece?

-Mike C.

[Pat Conlon]

Our carbs vibrate....no way around it. This vibration causes parts in our carbs to wear. The 2 main wear points are 1) Emulsion tubes. There is the hole at bottom of the brass emulsion tubes (aka: jet tubes, needle jets) where the jet needles seat. Because the needles vibrate, this hole becomes elongated and thus cause weird fueling issues and poor idle, and 2) The float needles. They get a wear pattern on the black rubber tip....this wear pattern is unique to the needle seat. If you reuse old float needles with fresh needle seats, problems can occur with getting the old needles to seat (and seal) properly.....IOW flooding.

That said....

There is a drain nipple at the bottom of each fuel bowl. There is a screw next to the nipple that opens and closes the drain.
Connect your fuel line to this nipple, open the screw, start your bike and let it idle, hold the clear fuel line vertically next to the fuel bowl. Look to see where the level of fuel is in relation to the gasket line of the fuel bowl.

Like so....

[Waiex191]

From the carb files section:
https://fjowners.com/index.php?topic=9560.0

I'm having similar issues which I hope to troubleshoot soon.
https://fjowners.com/index.php?topic=20362.0

Welcome to the forum!

[MikeC149]

Our carbs vibrate....no way around it. This vibration causes parts in our carbs to wear. The 2 main wear points are 1) Emulsion tubes. There is the hole at bottom of the brass emulsion tubes (aka: jet tubes, needle jets) where the jet needles seat. Because the needles vibrate, this hole becomes elongated and thus cause weird fueling issues and poor idle, and 2) The float needles. They get a wear pattern on the black rubber tip....this wear pattern is unique to the needle seat. If you reuse old float needles with fresh needle seats, problems can occur with getting the old needles to seat (and seal) properly.....IOW flooding.

That said....

There is a drain nipple at the bottom of each fuel bowl. There is a screw next to the nipple that opens and closes the drain.
Connect your fuel line to this nipple, open the screw, start your bike and let it idle, hold the clear fuel line vertically next to the fuel bowl. Look to see where the level of fuel is in relation to the gasket line of the fuel bowl.

Like so....

Ok, I will check it like that tomorrow. thank you. I might end up installing the float needle that came with the kit if it will mate with the needle seat better.

Someone posted this video too: This looks like pretty helpful.
https://www.youtube.com/watch?v=Bxx5Iw1xoVw

-MC

[MikeC149]

Our carbs vibrate....no way around it. This vibration causes parts in our carbs to wear. The 2 main wear points are 1) Emulsion tubes. There is the hole at bottom of the brass emulsion tubes (aka: jet tubes, needle jets) where the jet needles seat. Because the needles vibrate, this hole becomes elongated and thus cause weird fueling issues and poor idle, and 2) The float needles. They get a wear pattern on the black rubber tip....this wear pattern is unique to the needle seat. If you reuse old float needles with fresh needle seats, problems can occur with getting the old needles to seat (and seal) properly.....IOW flooding.

That said....

There is a drain nipple at the bottom of each fuel bowl. There is a screw next to the nipple that opens and closes the drain.
Connect your fuel line to this nipple, open the screw, start your bike and let it idle, hold the clear fuel line vertically next to the fuel bowl. Look to see where the level of fuel is in relation to the gasket line of the fuel bowl.

Like so....

On this is what I'm working with. This is after the bike running for 5 mins. Tapped on left carb, it stopped filling, but the float height is still too high I think???

[Pat Conlon]

Nope

Here's what to do....Unbolt the subframe to pivot it down lower for clearance to remove the air box,  leave the fuel line connected to the tank, unbolt the tank flip it around 180* and rest the tank on the subframe. The front of the the tank is now facing the rear of the bike and resting on the subframe where your seat would normally sit. If the tank is wobbly, strap it with a towel under the strap to protect your paint.
The fuel line is still connected to the tank so now you can still start and idle your engine.

Now you have proper access to the carbs to read your fuel level. That air box has got to go....You want the clear fuel line right next to the carb bowls. Remember, we are dealing in millimeters.

[MikeC149]

Nope

Here's what to do....Unbolt the subframe to pivot it down lower for clearance to remove the air box,  leave the fuel line connected to the tank, unbolt the tank flip it around 180* and rest the tank on the subframe. The front of the the tank is now facing the rear of the bike and resting on the subframe where your seat would normally sit. If the tank is wobbly, strap it with a towel under the strap to protect your paint.
The fuel line is still connected to the tank so now you can still start and idle your engine.

Now you have proper access to the carbs to read your fuel level. That air box has got to go....You want the clear fuel line right next to the carb bowls. Remember, we are dealing in millimeters.

I ended up removing the carbs, redoing the float heights since I got a tool to do it. I also used the needles that came in the kit since I'm using the kit's needle seats.  I put them at 22mm and the left side is no longer leaking! However, now the right side is leaking!!  Can't believe how sensitive it is.

[Pat Conlon]

Yea, moral of the story: Use new needles with new needle seats.

[Sparky84]

G'day And Welcome Mike

You might have to separate your carb rack, that tee has o-rings that do perish... just a possibility if all else fails.

[MikeC149]

G'day And Welcome Mike

You might have to separate your carb rack, that tee has o-rings that do perish... just a possibility if all else fails.

Hey I replaced the O rings.

The left side is no longer overflowing, but the right is now. Just to be clear, to fix this problem, with the carbs upside down off the bike, I need to push the tang downwards into the carb, correct?

[Sparky84]

Hey I replaced the O rings.

The left side is no longer overflowing, but the right is now. Just to be clear, to fix this problem, with the carbs upside down off the bike, I need to push the tang downwards into the carb, correct?

Good to see you replaced those o-rings Mike.
Pushing the tang the way you described will lower the fuel level in bowl.....whether this will fix the problem, that I cannot say.

[MikeC149]

 

Whelp I've had it with this fuckin thing. Pushed the tangs a little lower to set the float height and now the left side is leaking again worse this time while running . It's actually leaking into the airbox side. Whatever I've done has made it worse. It's like the fuel pump is in overdrive and the bike is not ready for all that fuel.  See pics.

[FJmonkey]

When you replaced the needle and seat for the floats, did you make sure they were for the 89+ carbs? The earlier gravity feed were larger and may not hold back the pressure from the pump.