FJowners.com

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 :flag_of_truce:

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.

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.

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.

Quote from: neo297 on June 03, 2014, 08:35:41 PM
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

Quote from: ribbert on June 04, 2014, 06:20:28 AM

Quote from: neo297 on June 03, 2014, 08:35:41 PM
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.

Quote from: andyb on June 04, 2014, 12:50:14 AM
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

Quote from: neo297 on June 03, 2014, 08:35:41 PMThere 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.

Quote from: ribbert on June 04, 2014, 06:20:28 AMWhy doesn't anyone put springs over their fuel lines to stop them kinking?

Quote from: Pat Conlon on June 04, 2014, 10:52:34 AMNot needed on the gravity flow bikes when the fuel line is routed correctly.

seems like a reasonable fix to me (popcorn)

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 .

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

Randy - RPM

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

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.

a drip pan will set you back about $2  :drinks:
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.

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.

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?

I can see 3 tubes under there but the dripping has stopped so I'll quit for now and regroup.

Tried tapping the carbs again tonite but the same leak is there from the rt side carbs. So it looks like its time to dig deeper. I'm siphoning the tank, any surprises to look out for taking it off?

Removed the tank and with better access to the carbs I tried the light taps again. Put some gas back in the tank and started her up...same old song. A steady stream shortly after starting slowing to a drip after shutdown and the drip stops after a couple minutes. Does this sound like internals that are worn/stuck or something outside the carbs? I'm at the point of removing the oem air cleaner so I can stop here if it's external. I can only see 3 drain tubes but apparently there are 4 or 5 in there, don't know if this is a factor. 12k miles on a stock setup, no known maintenance history for the carbs.

George:

Sounds like you'll need to pull the carbs, remove the float bowls, and see what's going on with them. Even with only 12,000 miles on the bike, having no history on the upkeep of the carbs puts you in this position. At least that's how I'm seeing it.

The float(s) could be stuck or dragging on their pins, because their gummed-up with old fuel varnish. The float needles could be doing it too. Float level(s) might be off. You don't know, what you don't know.

A good cleaning and inspection is in order. At least buy the RPM Racing o-ring and stainless steel screw kit before you dig into them.

If you're not up to doing it, consider sending them off to RPM Racing for a quick turnaround.

Good luck!

I seem to have cured my No. 3 carb. from leaking, by blowing down the overflow pipe. Did this without the engine running. Then with the engine running.  :good2: Cheapest option to try first :yahoo:

Quote from: FJ1100mjk on June 11, 2014, 01:59:14 PM
George:

Sounds like you'll need to pull the carbs, remove the float bowls, and see what's going on with them. Even with only 12,000 miles on the bike, having no history on the upkeep of the carbs puts you in this position. At least that's how I'm seeing it.

The float(s) could be stuck or dragging on their pins, because their gummed-up with old fuel varnish. The float needles could be doing it too. Float level(s) might be off. You don't know, what you don't know.

A good cleaning and inspection is in order. At least buy the RPM Racing o-ring and stainless steel screw kit before you dig into them.

If you're not up to doing it, consider sending them off to RPM Racing for a quick turnaround.

Good luck!

Depending on the cost I may go with RPM for the plug,n,play convenience but owning a Norton for 27+ years you gotta know your way around a toolbox.

Eliminator-like your idea, may give it a shot but a more permanent fix is probable. Luckily the leaks started Sunday morning warming it up in my driveway. Would have been a tough situation happening a couple hundred miles from home...

Thanks for the input gents.

HI
i fixed carbs with carb repair kits and tested and tested them by connecting fuelpump to hole carb package, finaly they didnt leak from over leaking hoses
Then i put them back and bike was running fine and i go to test drive everything vorked fine abouth 5 miles and then bike was startig run rough and woudnt
keep idle. i crumble back to my home and pull off carb package, they vere owerflovig to cylinders, please any anver to that? :dash2:, and my bike is still 3cv.
BIG but my tank has only one out line with some white tap which can used by wrench to cut off fuel supply , nothing else just direct line to filter then pump.
is this correct? Has prewious ovners don some modification to fuel system, carbs have one input not two and fuel lines are pretty thin 6mm i belive. i have
also electric reserve switch in panel next to choke.???

That all sounds identical to my '89 (3CV).  When you bench tested the carbs, did you angle them, as they do not mount EXACTLY horizontal? 

I would suspect your float level is not correct.  I would take them off to verify float level is midrange per the service manual (Per GYSM, spec is 21.3 - 23.3 mm or 0.84 - 0.92")
Please report back.


Ed

If the float height is right, you can snap to WOT from a 2krpm cruise and it'll pull cleanly (albeit not very well, but no spluttering).  Leaking is a lack of sealing, and that's a problem, not a misadjustment of the height.

PROBLEM SOLVED

One of new needleset needles wanted to stuck in needle frame, needle was little pressed down and aluminium in frame had little bulk. I smoothen lover part of needle and then it worked fine
Next i set fuel levels much lover tha than originals (needle was right but needleseat was deeper, so levels vere way too up).
So what i learned: dont buy cheap needle/repair set!, you got lot of work with them! :mad:. But thanks to you all with helping me.

I've had exactly the same problem on my '93, checked everything but would still reoccur from time to time, managed to break one of the posts trying to get the float pin out, repaired it with araldite out of desperation and it held for around 12 months without a problem, but the flooding still occurred on and off. Finally I bit the bullet and bought a new set of carbies off Randy, not long after it happened again, that was about 12 months ago and it hasn't happened since but I wonder if it's something other than a fault in the carbs. Could it be the fuel pump over- pressurizing, does it happen to earlier models without fuel pumps? Is the fuel pump really necessary, will the later models run on gravity feed?

Cheers, John.

Quote from: aussiefj on June 25, 2014, 07:27:44 AM
I've had exactly the same problem on my '93, checked everything but would still reoccur from time to time, managed to break one of the posts trying to get the float pin out, repaired it with araldite out of desperation and it held for around 12 months without a problem, but the flooding still occurred on and off. Finally I bit the bullet and bought a new set of carbies off Randy, not long after it happened again, that was about 12 months ago and it hasn't happened since but I wonder if it's something other than a fault in the carbs. Could it be the fuel pump over- pressurizing, does it happen to earlier models without fuel pumps? Is the fuel pump really necessary, will the later models run on gravity feed?

Cheers, John.

Firstly, fuel pumps are better (but that's another story) The gravity feed models have trouble just trying to get fuel into the carbs.   :biggrin:

The forum is never more than a few days away from someone raising this problem. Some blokes rip their carbies off every time this happens and clean them. I just accept that they have bouts of incontinence. Mine has only done this for the last 100,000kms. Sometimes it will do it three or four times in the one day, sometimes it will go for 20,000kms without happening.

Many different views are held on what causes it and how best to deal with it but it is very common. I either tap the bowl of the offending carby with a metal rod (that I carry at all times for just this purpose) and/or you can empty the bowls in place with the drain screw, they are easily accessible and only takes a few seconds. Back off the screw, let the fuel run out, tighten it up again.

While it is annoying when it happens, I know it comes and goes and don't think too much about it, just fix it and keep riding. One thing I have noticed is that it seems to happen more often when I have been creeping around at very low revs, like heavy traffic. I have also noticed that a big rev sometimes clears it.

Don't be disappointed in your new carbies, they all seem to do it regardless of age of mileage.

Noel

Bouts of incontinence, I've never thought of it like that, but I'm fast approaching that age so I guess I can accept that. I usually use the big rev to clear it, but I worry about raw fuel running into the inlet ports and contaminating the oil, does this happen?

John

Polish the insides of the seats up with a q-tip in a drill and some brasso or polish, brings them up smooth and better then new. Its definately the needles sticking open on most cases as the walls of the seats get a bit sticky.

One thing to look out for is flat spots on the side of the seats, previous owners or yourself may well have squeezed a little hard when trying to remove and causes them to go out of round.

I have just started a thread about a fuel pump that allows fuel by when shut off. It definitely was a leak after about 4 hours of sitting. The weight of the fuel above the carbs unrestricted can over power the floats.