1991 Johnson/Evinrude Models "EI" 40 thru 55 Service Manual, Page 86Get this manual
Pulse Limiter fttlng
r:jl The pulse limiter fitting for the VRO pulse hose has an integral
A clogged check valve might restrict VRO fuel and oil supply, causing serious powerhead damage1Remove the pulse limiter fitting from the pulse hose
check valveThe check valve is not serviced separately, but it must be clean to allow normal pump operation
rv anyBackflushdepositswith mild aerosol solvent to remove 2the valve carbon
If you find excessive carbon deposits, check the engine for causes of backfiring: Linkage adjustments incorrect Engine temperature incorrect Crankcase air leaks Carburetor problems Extended use of flushing attachment
3Position the fitting in the pulse hose with black nipple facing the pump4Secure the pulse hose with ratchet clampsPump