Random carb overflow...common?

[Easterntide]

I had my carbs done a few months ago by a 'local general mechanic' and that stopped my drip drip of fuel from my floats when i shut down the engine for a while. But for the last few weeks its back.
Being of limited skills i'm guessing the best remedy is to take the 91 FJ12 to a proper mechanic and let him have at it. But is this a common issue that just happens w carb'ed bikes or is it rare and obviously i need them cleaned and adjusted.

as a sidenote question; does backfiring under engine deceleration imply that the mixture is too rich or too lean?

thanks as always,
Don

[FJ1100mjk]

I had my carbs drip fuel from my floats when i shut down... is this a common issue that just happens w carb'ed bikes?

thanks as always,
Don

Answer: No.

Solution: Take the carb banks out, and send them to Randy@RPM Racing. He is the only person/carb guru that fix the carbs on these FJs correctly. He will inspect them, correctly diagnose the problem(s) they have, and fix them correctly. Anyone else, is just a poser, or carb guru wannabe.

As for the popping on decel, try adjusting the pilot air screws 1/4 turn in or out, then test, to see if it helps. Or just ride the bike and live with the afterfire. Besides, when riding an FJ, you get the most fun out of it when you're on the gas, not off.

[Easterntide]

Randy is on my 'winter' send list. But for now to send them there/service and back i'd be out of a bike for a too long period of time (i'm on the east coast of canada).

may suck it up and take it to my yamaha dealer and just pay the foolish hourly rate...at least then i'd have the ability to take it back if they overflow again right off the bat.

[red]

I had my carbs done a few months ago by a 'local general mechanic' and that stopped my drip drip of fuel from my floats when i shut down the engine for a while. But for the last few weeks its back.
Being of limited skills i'm guessing the best remedy is to take the 91 FJ12 to a proper mechanic and let him have at it. But is this a common issue that just happens w carb'ed bikes or is it rare and obviously i need them cleaned and adjusted.
as a sidenote question; does backfiring under engine deceleration imply that the mixture is too rich or too lean?
thanks as always,
Don

Don,

Is your fuel filter good?  If the fuel filter gets too clogged up, the fuel pump may just rupture the filter and send dirty gas to the carbs.  You'd be cleaning the carbs repeatedly then, and it is not the fault of the mechanic.  If you do not know how old the fuel filter may be, then just change it, and keep notes on such maintenance, for the future.

Do all gas-related work outside.  Your fuel pump should block the flow of gas from the tank when the bike is OFF.  If you have drips, then one (or more) needle-and-seat in the carbs will have a speck of grit in it, sure, but the fuel pump is not doing the full job, also.  Grit from the gas tank can make the fuel pump leak gas through, as well as the carbs.  Siphon some gas from the tank, using the hose as a "vacuum cleaner" to suck any grit from the bottom of the tank.  Catch the siphoned gas in a clean container, and see what comes out with the gas.  Use a magnet to try to pick up any grit that you catch in the gas.  If the grit sticks to the magnet, you may have found the problem (rusty tank).  After the gas settles in the catch-container for a while, you can pour it back into the tank (put a coffee filter in the funnel).  Do not dump in the last cup of gas, which has all the grit.  You can siphon the tank bottom again, until you get a lot of the grit out of your tank.  Once the tank is cleaned out, you can have the fuel pump run maybe a gallon of gas into a clean container, to get out any grit in the pump.  With a little luck, the fuel pump will seal again as it should, when you turn it off.

Stick a strong (neodymium) magnet to the bottom of the fuel filter, to catch any rust in the gas there.  Do not remove the magnet from the filter, until you have removed the filter from the bike.

Backfiring on deceleration is a rich condition, but the leaky carb may be the problem there, and not the carb settings.  I would not adjust the carbs, to fix a problem caused by grit in the gas.  Try a shot of Seafoam in the gas, first.  With a clean gas tank, clean fuel filter (with magnet), and a fuel pump that seals when off, then you may not need to tear into the carbs again for a good while.  If the backfiring continues, though, there may still be some grit in the needle-and-seat.

Cheers,
Red

[simi_ed]

Don, I hope your wallet is ready for that one, assuming your local Yammie (st)dealer will even touch your 'old dinosaur'. 

For my money, your better off either sending them to Randy, or learning how to do the work yourself.  There is an excellent carb service write up by our resident carb guru, David Raforth, not to mention Randy as a source of info and a few others that have done a fair share of carb service, all available to you here.

I assume you have tools and a place to work ...  You should order the carb screw kit from Randy, which includes all the orings you'll need.  Get a set of #40 pilot jets, in case your bike doesn't have them already.  (A spare set on hand doesn't hurt too).  Read David's walk through and have at it.  You can even build your own manometer to sync the carbs when your done (for not too much $$$)! 

Do this and you'll feel like a real champ, because you'll have slayed the FJ Dragon, the mysterious CV carb!

Ed

[Easterntide]

Thanks Ed et al,

The tank was professionally re-coated this spring. clean as a white whistle inside. Also at that time a new fuel filter was installed from RPM. i run seafoam in the tank frequently but haven't done a direct in the carb shot (does that really work?)
I've balanced the carbs using a homemade manometer but that was quite easy really.

My local shop wants 90$/hr and estimate 4hrs for the carbs and another 4 for valves (if i want those done). So since i'm not nearly that rich i'll pass. Another reputable private shop will do both in 5-6hrs @ 60/hr +20$/carb kit.

one challenge i have is that working solo on a problem as potentially important as this is that if i get stuck/screw up then i have no one to bounce ideas off of. can be frustrating/slow/dangerous.
so likely i'll be dropping 400$ish and get someone to do it....sigh.

[rktmanfj]

so likely i'll be dropping 400$ish and get someone to do it....sigh.

You could probably express ship it to Randy and back for less than that, and know it's done right...       

[Easterntide]

hmm. ok i'll send him an email now...

[aussiefj]

This seems to be quite a common problem, I've had it as well, someone here described it as a random incontinence problem probably due to old age, how about FJ incontinence pads Randy?

[Easterntide]

exactly...just find a way to route the overflow BACK into the tank instead of onto my driveway...

[aussiefj]

On a serious note when the carbs do over flow like this does any of the fuel actually run in to the engine via the intake and so contaminate the oil or does it all end up on the ground?

John

[the fan]

On a serious note when the carbs do over flow like this does any of the fuel actually run in to the engine via the intake and so contaminate the oil or does it all end up on the ground?

John

In most cases it flows out onto the ground.  With the carbs oriented horizontal on the FJ it would take a complete failure of the needle and seat to flood into the enging instead of out the bowl overflow.

[anson45]

My best guess is the floats are contaminated. RPM sells OEM fuel filters, that is what you have? An aftermarket supplier was selling plastic filters that had glue that was dissolved by the ethanol in the gas. The glue became little tiny balls. Someone is going to have to look in the float bowels.
Anson

[rlucas]

...Someone is going to have to look in the float bowels.
Anson

Yeah. Clean the shit out of 'em.

I just had mine off four effin' times attempting to solve a very similar issue with an overflow situation. Removed, cleaned, reassembled, repeat. Finally solved with Randy's o-ring kit and a good polishing of the float needle seat. Squeaky clean and no leaks.


rossi

[ELIMINATOR]

Mine has done this once or twice. Last time I stopped it happening by blowing down the overflow pipe from which the fuel was dripping. Engine running at the time, cured it.