hey

was kinda hoping my mikuni would make it till i got my tbi on but she is acting up!

A few weeks ago i went on a highway drive about 160 each way.. on my way to my destination she ran pefect, good power, decent mpg i was actually impressed.


Except for the way back she acted up on me, and has not got any better with time as i wished but doubted.

Basically on the high way on the flat she can not hold 100 km/h she just slowly bogs down and you have to step it done more till you are almost at the floor, then the auto downshifts, she picks up speed all is good till it shifts back to OD, then the slowly bogging down all over again.

This condition is also accompanied by TERRIBLE MPG at the same time.

Any ideas to limp this carb for a few more months?

Thanks

Mike

Block the bowl vent and take it for a test drive. The bowl vent is one of the larger lines and should connect across the valve cover.

Just for my own curiosity what is the problem i could uncover by doing this?

If it fix s it just leave it plugged?

failed bowl vent valve...

So if it is failed can i just run with out it?

Is that valve the white one on the fire wall?

No. Valve is in the carb. If you block the hose, it will run ok, but you may have some hot start problems due to fuel boil in the bowl. And you will contribute to the ozone pollution problem.

well i took the hose for the carb vent off and plugged it up, it deffinitly did not fix it, any other ideas?

Pull dipstick and smell for gas in oil. Fuel filter. Fuel pump. Water in fuel.

oil does not smell like gas, but that is cause i prob dont hit the high way much.

i have ran several tanks of fuel and same problem, not sure if it could be water.

Fuel filter was changed

Fuel pump, no idea, i know it pumps fual but much past that i am not sure

If no gas smell in oil, FP diaphragm is good.

Water in fuel will sit in the bottom of the tank, and highway driving will let the puddle settle near pickup. Try a can of fuel drier or a bottle of rubbing alcohol in the tank.

Remove air filter lid and look down carb throat with engine idling. See any fuel droplets vaporizing on the throttle plate (choke must be open, engine warmed up). If so, carb needle valve is leaking and float bowl is flooding into carb, making an extremely rich mixture. Downshifting puts engine in WOT mode, which needs a richer mix. Upshift puts you back in lean cruise, and the rich mixture causes power loss.