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Drain tubes from carbs spilling out when near redline

Started by gumby302ho, July 29, 2015, 09:51:28 PM

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gumby302ho

 My 86 runs great and starts great and idles great and does not blow smoke but, when I roll on the power and crank it through the gears the dump tubes will piss out a few or more healthy drips that hit the exhaust header and burn off while leaving a nice stain on the stainless. I went passed my daughter in full kookaloo mode and she said it puffed a little when I shifted gears and looked really cool  :dash2: . It only seems to be when its near or at redline, I must admit I am really hard on the old girl. Is this PCV froth and moisture coming out, I am thinking of mounting a little bottle next ride to collect some just for a sample to check it out plus its making a mess out of the header. Oil level has not dropped, bike runs great, what do you guys think is going on, is this a normal issue when these motors are pushed really hard?   

Pat Conlon

The title says it's coming from the carb's drain tubes, yet you mention PCV froth...?
Apples and Oranges.
Fuel will come from the carb tubes and oil and blowby gasses will come from you crankcase vent tube.

So, I'll try and cover both conditions.

If it's fuel dripping out the carb bowl vent hoses, check your float heights, and replace your float needle seat o rings.
Sometimes if the floats are set on the high side, when under power your floats are lower, gas is filling the bowls to feed your thirsty engine. When you roll off the throttle to shift, gas is still flowing into the carbs. If the floats are slightly too high, the bowls will momentarily overfill and a little bit of gas washes out the float vent tubes until you open the throttle again and the fuel level drops in the bowls.

If it's oil froth coming out your crankcase vent hose and you have UniPods, put a longer hose on it and a K&N filter.
If you still have the crankcase vent hose connected to your stock airbox, not much can be done except to put a small catch can where your airbox drain tube terminates above your collector box.
It's normal for higher mileage FJ's to produce a lot of blowby from the crankcase when visiting the kookaloo zone.
1) Free Owners Manual download: https://tinyurl.com/fmsz7hk9
2) Don't store your FJ with E10 fuel https://tinyurl.com/3cjrfct5
3) Replace your old stock rubber brake lines.
4) Important items for the '84-87 FJ's:
Safety wire: https://tinyurl.com/99zp8ufh
Fuel line: https://tinyurl.com/bdff9bf3

gumby302ho

Quote from: Pat Conlon on July 30, 2015, 01:09:55 AM
The title says it's coming from the carb's drain tubes, yet you mention PCV froth...?
Apples and Oranges.
Fuel will come from the carb tubes and oil and blowby gasses will come from you crankcase vent tube.

So, I'll try and cover both conditions.

If it's fuel dripping out the carb bowl vent hoses, check your float heights, and replace your float needle seat o rings.
Sometimes if the floats are set on the high side, when under power your floats are lower, gas is filling the bowls to feed your thirsty engine. When you roll off the throttle to shift, gas is still flowing into the carbs. If the floats are slightly too high, the bowls will momentarily overfill and a little bit of gas washes out the float vent tubes until you open the throttle again and the fuel level drops in the bowls.

If it's oil froth coming out your crankcase vent hose and you have UniPods, put a longer hose on it and a K&N filter.
If you still have the crankcase vent hose connected to your stock airbox, not much can be done except to put a small catch can where your airbox drain tube terminates above your collector box.
It's normal for higher mileage FJ's to produce a lot of blowby from the crankcase when visiting the kookaloo zone.

Thanks for the reply Pat, your knowledge has helped me many times since I have been on this forum concerning all things FJ!! I love this bike. I will admit that the FJ-09 really has my attention, it has bang for the buck in spades!  Cheers
   Don