Yeah, that voltage is a bit low. I am not what the low voltage tolerance on these carts are but something in the 10s may well not be enough to fire the coil.
There is a testing procedure located in this thread:
https://buggiesgonewild.com/showthre...ting+procedure
You may want to follow it to see if you can identify where you are dropping. Unfortunately, low voltage causes can occur
after a noted point of failure, however.
A lot of times, poor voltage is the result of a poor ground do to corrosion or a bad wire somewhere. I would unhook all grounds, clean them shiny and reattached while using some dielectric grease.