Take the roof panel off above the engine. You see the hard fuel line that goes from the fuel fitler bowl, to the metering pumps near the pushrod tubes? At the left hand end of that, is the soft 'fuel return' line. You probably have a leak in this line, either at one of the Ts at the injectors, or just somewhere in the run.
Got an O Reillys auto near you? Source some Gates safety strip (
https://www.oreillyauto.com/detail/...ripe-fuel-hose/gats/27000?q=gates+27000&pos=0) and some new plastic 1/8" vacuum tees (and some small zip ties, to zip tie the ends for additional safety at every seam). You may be able to reuse the Ts up top, but if you can buy new, I would. Just cut to length and replace whats there. You will want to put a dab of motor oil (or similar) on the barb ends and the ends of the soft lines, to get them together more easily.
You will need to remove the muffler, and the air filter housing to get to the fuel lines easily, but its worth it.