Fuel in Oil

[Nimbus]

Help. Can someone explain the cause and cure for the crankcase get filled with gas.
Looked at club files and did not find an answer.
I have had my '92 FJ since 2007 and some 100,000 km. winter storage in my heated garage and monthly battery charge and Startup. The bike is well maintained, new float needle and seats (twice) float height meticulously adjusted.  Yet went to start it and soon had gas and oil flowing out of the crank vent. Crank vent with a KN filter as I am running Pod filters. Sadly this is the 3 or 4th time it has done this, once year or so. How does so much fuel get into crank. I have a new fuel pump, but it happened as well with the original.
Do I install a shutoff solenoid at tank? But is the fuel pump itself not blocking flow, I mean it holds prime even after weeks not started.
I am reaching out to my fellow FJ friends as I am at a loss for a fix.
Thanks
Henning AKA - Nimbus

[RPM - Robert]

1) Your fuel pump is no good. It shouldn't let fuel continue to flow when not on.
2) Float needle tips should be sealing and not letting fuel by or your floats are stuck or out of adjustment. They shouldn't be letting fuel by.
3) Needle seat o-rings are bad and are letting fuel by.

1 Is guaranteed.
2 & 3 could be either or; or both.

[Urx]

That was my thought
Fuel is passing through the fuel pump an overflowing a carb or carbs and draining into the lower casings

If the fuel pump is not an original yamaha one then you need to look there as action #1 and likely replace with one that does actually lockoff the flow.
After that is sorted one or more carbs are leaking gravity fed fuel into your engine
The carbs should show which is / are leaking with some bench testing
A cup under each carb should show which one(s) need attention

[Nimbus]

Carbs I will say GOOD, ok fuel pump and it was slated as a FJ replacement. Looks like I need a RPM order  placed. 
Thanks

[red]

Carbs I will say GOOD, ok fuel pump and it was slated as a FJ replacement. Looks like I need a RPM order  placed. Thanks

Nimbus,

Sorry, but no.  The fuel pump should block fuel flow when off.  The carbs (floats) should block fuel flow, even if the fuel pump does not.  The carbs may be fine in every way for driving, but a leaking needle-and-seat/O-ring seal will still allow gasoline to flow into the crankcase.  Replacing those few parts at the floats will be all you need, there, although a new fuel pump is also needed.  I believe RPM can supply just what you need.

[Nimbus]

 

Carbs I will say GOOD, ok fuel pump and it was slated as a FJ replacement. Looks like I need a RPM order  placed. Thanks

Nimbus,

Sorry, but no.  The fuel pump should block fuel flow when off.  The carbs (floats) should block fuel flow, even if the fuel pump does not.  The carbs may be fine in every way for driving, but a leaking needle-and-seat/O-ring seal will still allow gasoline to flow into the crankcase.  Replacing those few parts at the floats will be all you need, there, although a new fuel pump is also needed.  I believe RPM can supply just what you need.

[twood1972]

Needle seat o-rings for sure.

[RPM - Robert]

Red is correct. Two fail safes.

One fuel pump should stop flow, it is not, so it has failed.

Two the float needles/float should stop it. Again something here has failed, be it float needles or needle seat o-rings.

If one fails two should still stop fuel flow while off. Since it is not the second fail safe needs to be addressed. Ideally both should be fixed but at minimum carb internals need looking at.

We do have everything in stock including new Yamaha fuel pumps.

[Nimbus]

Well she is back running, sounding awesome. Replaced fuel pump, ultrasonic carbs, new o-rings and the seat/needles replaced. I feel confident that will the last of that issue. Thanks to FJ friends and of course RPM.
Henning

[WyattJT]

I'm gonna resurrect this thread if I may. I had the same problem, the carbs are sorted out now and the engine is running well.

Before the carb flooding, the bike rode fine - I only have about 12 miles riding this bike since I bought it.

Now my clutch won't engage and I'm wondering if it might be related to fuel in the oil.

The bike starts and runs. The gears seem to shift ok. The rear wheel just spins freely no matter what. The clutch lever feels really stiff to me, but I'm new to the bike, so I don't have any history with it yet.

And ideas are appreciated. I was just reading some forum posts and watching some videos. I'll try to bleed the clutch when the weather dries up (probably next week). I ordered a clutch cover gasket and a slave rebuild kit from RPM. Don't have a delivery date yet.

[RPM - Robert]

Wyatt, just saw your order as I have been building carburetors all day. Since you are in Ohio you will see it sometime next week.

[twood1972]

Wyatt.
My FJ sat in a shed for 14 years crank case was filled to the top with fuel, for how many years, I don't know. After I got her sorted out, clutch slipped in 4th and 5th but only during height toque demands. Was the slippage caused by fuel in the crank case? Possibly, but I don't think clutch plates soaked in fuel once and for a short time would cause total clutch failure. Slave cylinder rebuild definitely needed.

[WyattJT]

Slave cylinder rebuild definitely needed.

Thanks. I'll try that first.

[Motofun]

If your clutch plates saw gasoline for any amount of time I would recommend disassembly of the clutch.  Keep the plates and steels in order, let them dry out then re-soak the fibers in your preferred MC oil prior to reassembly.  This is a good time to inspect and mic them too.