A VERY COMMON PROBLEM WITH THE MULTI FUEL ENGINES IS FUEL MAKING ITS WAY INTO THE CRANK CASE. THERE ARE A FEW KNOWN WAYS THIS CAN HAPPEN.

LEAKING BOOSTER PUMP SEAL

LEAKING FUEL DENSITY COMPENSATOR

LEAKING MANIFOLD FLAME HEATER

LEAKING HYDRAULIC HEAD O RINGS

IF YOUR FUEL DENSITY COMPENSATOR HAS BEEN BYPASSED, AND YOU HAVE PULLED THE BOOSTER PUMP OFF THE INJECTION PUMP WITH THE LINES STILL CONNECTED AND TURN ON THE INTANK PUMP AND FOUND NO LEAK, THEN CHANCES ARE THE HYDRAULIC HEAD O RINGS ARE THE CULPRIT. THE MANIFOLD FLAME HEATER HAS ONLY A SLIGHT CHANCE OF LEAKING IN.

HERE I HAVE ASSEMBLED A KIT OF 3 O RINGS THAT YOU NEED TO RESEAL THE HYDRAULIC HEAD AND THE FUEL CUTOFF SHAFT. THEY ARE VITON O RINGS COMPATIBLE WITH TODAY'S ULTRA LOW SULFUR DIESEL.

THIS IS THE BEST FITTING O RING KIT ON THE MARKET.

MOST VENDORS ARE SELLING KITS THEY TRIED TO "MATCH UP" WITH OLD O RINGS. THE KITS WE SELL ARE THE EXACT SIZES CONFIRMED BY THE PUMP MANUFACTURER. THE CORRECT SIZE O RINGS ALLOW YOU TO TIGHTEN THE FUEL CUT OFF MORE THAN THE COMMON "LEAVE IT LOOSE" ADVICE YOU WILL SEE OFTEN MENTIONED IN FORUMS AND ON VIDEOS.

IT IS STILL ADVISED TO CHECK MOVEMENT OF THE CUT OFF LEVER AFTER INSTALL FOR PROPER MOTION AND SNAP BACK ABILITY. 

HERE IS A LINK WITH INFORMATION REGARDING PROPER AND IMPROPER WAYS TO REMOVE THE HYDRAULIC HEAD IN ORDER TO CHANGE OUT ALL OF THESE O RINGS. BE SURE TO READ MOST OF THIS THREAD IN ORDER TO MAKE SURE YOU ARE DOING THIS RIGHT.

http://www.steelsoldiers.com/showthread.php?14688-multifuel-fuel-pump-hydraulic-head-removel