5. FUEL SYSTEM MXU 500 IRS Check top cap and spring for cracks and damage. Top Cap Spring Spring Covers Check the diaphragms (coasting enrichment valve and accelerating pump) for tears. Check the spring (coasting enrichment valve and accelerating pump) and cover (coasting enricher and accelerating pump) for damage. Diaphragms Spring Jet Needle Check jet needle, needle jet, slow jet, needle jet holder, main jet, and pilot screw for bends, wear and damage. Needle Jet Slow Jet Needle Jet Holder Pilot Screw Main Jet 5-15