FJ leakin fuel

[JOMPPA10]

BIG HI to everyone here

Iam newbie in this forum, may i introduce myself: iam 46 yrs old and my bike experiences are 350 yamaha 2stroke back in 80`s few 125cc also 80´s.
I have been avay for some time, now i bought yamaha fj 1200 1990 model and i have riding happily some weeks.

My problem is: last owner was put electricfuel pump off and connect fuel lines direct from tank to carbs, it worked fine about 20-40 miles driving
but then bike die ,few minutes off road and then ican drive again. Iwas thinking that fuelpump was the thing for that problem, i fixed fuelpump
and reconnected it to fuellines. Next i drive few miles in city and i notice that my bike sound was like harley and stiff responce to throttle and
fuel smell. I drove parking lot to some mall and checked bike

Fuel was leaking from carbs overleaking hoses?
Iam i right i suspected that carbs fuel needles are leaking?, or something else?

sorry my bad english, iam only finnish

[theLeopard]

I just fixed this symptom.
Pull the carburetor off, clean it, replace anything worn, and reassemble.
If you're still leaking there is a laundry-list of tests you can perform; I was lucky.

[neo297]

First off welcome, I have an 86 with gravity feed and an 84 with a 92 motor and fuel pump. You seem to have two issues the first the bike dying with the gravity flow set up - fuel line direct to tank and the leaking after reconnecting the fuel pump.
     When the bike dies after 30 - 40 miles-There can be several issues with the gravity feed system specifically the routing of the fuel line which as the bike heats up the lines can soften and kink thus limiting fuel flow to carbs. I'm not sure a few minutes rest would correct this but none the less its worth checking, the gas filler cap may not vent properly thus allowing for vapor lock and decreased fuel flow to carbs until vacuum is dissipated.You can try opening the filler cap when it sputters and see if it runs well again without waiting.
      Leaking fuel with fuel pump reconnected-With the fuel pump system it should use smaller fuel lines and smaller needles and seats gravity feed uses larger needles and seats. If you use a fuel pump on a gravity converted set up the pressure can overwhelm the needles and flood the carbs causing leaking. Can you tell us if there is a single fuel line into  the carbs between carbs 2 and 3 or 2 fittings one t fitting between carbs one and two and one between 3 and 4. These are a couple of things to check and let us know what you find. Also what petcock do you have gravity feeds should have a vacuum line to the intake manifold so when bike is off no fuel flow with fuel pump no vacuum line needed as pump acts as fuel stop when off. These things will help to know which system your bike is set up for.

[andyb]

1990 should be a 3CV, a fuel pump model from the factory.

Roughly translating, the prior owner removed the pump and converted it to gravity.  The gravity fed system uses a strange and fussy fuel hose routing; if it's imperfect, the motor starves for fuel after a bit of use.  You reconnected the fuel pump and rerouted things, so you should be back to the original configuration.  The fuel pump models can also be snotty about their line routing, but less so than the gravity models (84-87).

There is a check valve in the fuel pump that should prevent leaking when the engine is off. 

If the engine is running and there is too much fuel in the carb bowls, there's three things that can usually be the issue.
1-  The float needle seats are retained in the carb bodies with orings that can turn rock hard and leak.
2-  The float can get stuck in the down position.  Usual cure is a hard wheelie, riding over a large sharp bump, or a gentle tap on the carb body with something long and a small hammer.
3-  The float needle has a worn tip, or has a chunk of debris caught between it and the seat, preventing it from shutting the fuel flow off.

In any of these cases, start by ensuring that you have clean fuel in the tank.  Rust from the tank or particles in the fuel can prevent the float needle from seating.  If the problem persists, you will want to replace the orings that retain the float needle seats.  It's a headache of a job, as they are often pretty well frozen in place.  It's possible that the prior owner attempted this and distorted the shape of the upper part of the seat, where the needle goes through, preventing it from moving freely, which will make it tend to stick in a given position.  While you are doing this, inspect the condition of the float needle and seat, replacing them if there's excessive wear.

Don't know finnish, so I cannot translate the other direction.

[ribbert]

There can be several issues with the gravity feed system specifically the routing of the fuel line which as the bike heats up the lines can soften and kink thus limiting fuel flow to carbs.

Why doesn't anyone put springs over their fuel lines to stop them kinking?

Noel

[Pat Conlon]

There can be several issues with the gravity feed system specifically the routing of the fuel line which as the bike heats up the lines can soften and kink thus limiting fuel flow to carbs.

Why doesn't anyone put springs over their fuel lines to stop them kinking?

Noel

Not needed on the gravity flow bikes when the fuel line is routed correctly.

[JOMPPA10]

1990 should be a 3CV, a fuel pump model from the factory.

Roughly translating, the prior owner removed the pump and converted it to gravity.  The gravity fed system uses a strange and fussy fuel hose routing; if it's imperfect, the motor starves for fuel after a bit of use.  You reconnected the fuel pump and rerouted things, so you should be back to the original configuration.  The fuel pump models can also be snotty about their line routing, but less so than the gravity models (84-87).

There is a check valve in the fuel pump that should prevent leaking when the engine is off. 

If the engine is running and there is too much fuel in the carb bowls, there's three things that can usually be the issue.
1-  The float needle seats are retained in the carb bodies with orings that can turn rock hard and leak.
2-  The float can get stuck in the down position.  Usual cure is a hard wheelie, riding over a large sharp bump, or a gentle tap on the carb body with something long and a small hammer.
3-  The float needle has a worn tip, or has a chunk of debris caught between it and the seat, preventing it from shutting the fuel flow off.

In any of these cases, start by ensuring that you have clean fuel in the tank.  Rust from the tank or particles in the fuel can prevent the float needle from seating.  If the problem persists, you will want to replace the orings that retain the float needle seats.  It's a headache of a job, as they are often pretty well frozen in place.  It's possible that the prior owner attempted this and distorted the shape of the upper part of the seat, where the needle goes through, preventing it from moving freely, which will make it tend to stick in a given position.  While you are doing this, inspect the condition of the float needle and seat, replacing them if there's excessive wear.

Don't know finnish, so I cannot translate the other direction.

Thanks Andy , i belive thats nothing  havent done by original fuel lines etc.., only by-pass fuel pump. I fixed pump ( no rust etc. in tank) and reconnected it worked fine abouth 3 days but i only drove abouth 5km per day. Next weekend i drove abouth 20-40 km in city and i smelled gas odour when stopped bike in street lights, then i go to parking lot and check and fuel was leaking ewen when engine has stopped (it stopped  abouth few minutes later) I think that issue is leakin needles, hope fingers crossed.
and i ordered carb fixing set x 4 , hope that solve issue

[theLeopard]

There can be several issues with the gravity feed system specifically the routing of the fuel line which as the bike heats up the lines can soften and kink thus limiting fuel flow to carbs.

Why doesn't anyone put springs over their fuel lines to stop them kinking?

Not needed on the gravity flow bikes when the fuel line is routed correctly.

seems like a reasonable fix to me

[JOMPPA10]

Now i got these Yamaha FJ 1200 1989 (1200 CC) - Carb Repair Kit from local dealer, orderered kits to all 4 carbs . these kits consits needle,housing for needle 3 o-rings and bowl gasket is that enough ? , hope these help with my issue .

[racerrad8]

Is there supposed to be a picture showing the kits you received?

Randy - RPM

[JOMPPA10]

Idont know but know but in in deliwered pacs were codes CAB-Y30

[magge52]

Well, here's another set of leaking carbs.afaik there hasn't been any carb work done. 12k miles on stock 92. Tried gentle taps but now there's a steady drip every  3-4 seconds. Do I have a fuel pump issue with a steady drip? Don't want to leave it in the garage like this.

[theLeopard]

a drip pan will set you back about $2 
don't forget to check the float height on your needles. if the needles are sealing properly you should probably run a compression check so the guys have more info to work with.

[magge52]

Fumes leapord. The garage smells with the doors open but fortunateky the dripping has stopped. Maybe took a bit for the bowls to drain. Looks like the leak is coming from the right overflow (sitting on the bike) so I'm assuming its one of those 2 carbs.

[theLeopard]

if it's gonna leak overnight just close the petcock and/or disconnect the gastank.
check it in an hour or two, carbs should be level by then.

I've got a '92 and I've got 4 overflow hoses +1 more, how do you only have 2?