MustangBY6

My Feedback: (14)

I have a Walbro SDC 80 on a Sachs 4.2 that I bought used about 6 months ago. When I tried to start it the best I could get was a weak idle. Also, as soon as the engine would die, I would lose prime and I could see the fuel go out of the fuel line and back into the tank.
So, I put a new kit in the carb. Upon disassembly I discovered that the check valve diaphram was not even installed on the fuel pump side.
After reassembling and reinstalling the carb I was able to get the engine running relatively well.
However, now when the engine is running at an idle I have fuel dripping from the throat of the carb. As soon as I go to full or mid throttle (or stopped) the drip goes away.
Does anyone have any idea why it may be dripping fuel?
The only other clue I have is that the low speed idle could be a little bit better. The transition to full throttle is not glass smooth but not real bad. I have not been able to adjust this to perfect yet.
Secondly, this engine will continue to run even when the throttle butterfly valve is completely closed! The only way to kill it is to either pinch off the fuel line or shut off the ignition! Shouldn't I be able to stop it by closing the throttle all the way?
I should also mention that this is my first attempt at a gasser but I have fair mechanical skills.
Any ideas?
Thanks in advance.
Russell

Tired Old Man

My Feedback: (1)

The needle height under the diaphragm is incorrect. It's being held slightly open. That's the drip problem. Fix that and see if the other issues persist.