I don't use a pump with my Moki 180.. don't need it. It runs with needle open about 2.5 or so turns out.. and the low end disc lined up notch to notch. It does like to start WET.. I prime it until it spits just a tad of fuel on my thumb... then just a back-flip and its running.

Don't drill a thing... . especially that back-plate... you might just end up plugging it back up..... as these engines don't need pumps unless you're running fuel from the rear of the fuselage.. in any standard aerobat or warbird though... no fuel pump is needed. I use an 18x10 Menz prop, and any kind of FAI fuel I can find.. even made my own a few times.. theres on real savings doing that so I just buy it ready made now..

Theres an obstruction somewhere though... whether its in the fuel delivery, or air system, or fuel tank, or pressure fitting... somewhere somethings not right. I've used an OS 4-stroke plug from day one also, with no issues(that I would install immediately)....... medium fuel tubing also works fine. Theres not any magic $50 pump that's going to fix whats wrong with your engine.. Don't spend money until you know what's wrong... as you could end up spending alot that you might not need too.

These are one of the best engines you'll ever own... but if you get tired of fighting it.. PM me.. I'll take it off your hands.