2003 GTI LE Accelerator pump leak after rebuild

[cairnclub]

Hey guys, still working on my friend's 2003 GTI LE 717cc.

Just rebuilt the carb with genuine mikuni and installed a new diaphragm on the accelerator pump. Installed all new fuel/oil lines and filters/selector valve. New intake gasket and rotary valve o ring. Oh and it has 140 psi both cyls

Tried to start it today after priming the fuel and I noticed the accelerator pump leaking heavily from the little hole between the bottom 2 screws every time the throttle was pulled. It wouldn't start either.

What did I miss inside the accelerator pump? It did not leak before the rebuild.

Thanks

 

[etemplet]

You are going to have to disassemble it and take a look. Lots of people don't mess with the accelerator pump diaphragm because of fitment problems. That may be your problem and there are threads on the forum that mention replacements. You can look into resizing the low speed jet and eliminating the accelerator pump altogether if need be. I now test the accelerator pump while the carbs are fully assembled but not installed on the ski. It is as simple as feeding fuel to the pump and letting it do its job. You can visually see the spray and the amount. That little system can have a number of gremlins. Good Luck

 

[cairnclub]

Sorry for the late reply. I just can't think of what went wrong when reassembling it? The new diaphragm was an exact fit. It was my first time taking apart an accel pump/reassembling. Is that hole just for the diaphragm to breathe?

May have to just delete it

 

[etemplet]

The hole is an air vent and it is needed. You have to find the leak path or eliminate the pump.

 

[cairnclub]

Well I got busy but am still working on this - took it apart and found nothing visually responsible - interestingly the ski actually runs pretty well like this. Obviously this is a huge safety hazard and I will be fixing it but wanted to note that.

It seems fuel is getting to the side of the diaphragm it should not be (pic). and leaking out the breather hole as well as where the diaphragm rod goes through the pump

I cleaned everything and reassembled it and it is doing the same thing.

This is weird - maybe I got a bad diaphragm?