5 ton, M 931A2, prime from zero fuel !!!

[Jericho]

Hi guys and gals, just thought I would drop a bit of info that helped me. Changed all my filters oil, fuel, Trans ect, Noticed when I took the large Fuel filter housing down to change the element ( the one just inside the drivers side fender opening, RIGHT UNDER YOUR FEET. The housing has an air fill valve (purge) in the top , line runs from there to the prime manual pump button. It was les than half full , truck had been running normally just moments before to warm up fluids. Changed the filters , filled the bowls / filters to the tops and cranked, and cranked, and cranked, Used start fluid (usually does the trick) would light off but not sustain. TRIED the manual priming button , pumped, pumped and pumped, felt no resistance . Have more than a few diesels , Japanese diesels light right off when refueled after running dry with minimal effort !

Out of curiosity I pulled the supply line from the large filter housing to the prime button, It was dry. So I back filled the line and with a funnel with fuel, Tightened it up, pumped prime button about ten times with resistance and could hear the injectors clicking. Cranked it and it fired right up lickety split !!! Have read woes and knashing of teeth on priming in previous post, Have struggled more than once my self when some one decided to "borrow, and not return " my fuel, from both tanks and i didn't notice until it ran dry. This method was a snap ! fired right up with about ten pumps on the prime button ! if it helps any one in future , here it is thanks for your time !

 

[Elijah95]

Hi guys and gals, just thought I would drop a bit of info that helped me. Changed all my filters oil, fuel, Trans ect, Noticed when I took the large Fuel filter housing down to change the element ( the one just inside the drivers side fender opening, RIGHT UNDER YOUR FEET. The housing has an air fill valve (purge) in the top , line runs from there to the prime manual pump button. It was les than half full , truck had been running normally just moments before to warm up fluids. Changed the filters , filled the bowls / filters to the tops and cranked, and cranked, and cranked, Used start fluid (usually does the trick) would light off but not sustain. TRIED the manual priming button , pumped, pumped and pumped, felt no resistance . Have more than a few diesels , Japanese diesels light right off when refueled after running dry with minimal effort !

Out of curiosity I pulled the supply line from the large filter housing to the prime button, It was dry. So I back filled the line and with a funnel with fuel, Tightened it up, pumped prime button about ten times with resistance and could hear the injectors clicking. Cranked it and it fired right up lickety split !!! Have read woes and knashing of teeth on priming in previous post, Have struggled more than once my self when some one decided to "borrow, and not return " my fuel, from both tanks and i didn't notice until it ran dry. This method was a snap ! fired right up with about ten pumps on the prime button ! if it helps any one in future , here it is thanks for your time !

Great to hear you got it running, but the noise you referred to as “injectors clicking” is actually your pressure overflow valve mounted on the outside (driver side) area of the pump, it’s a banjo bolt with a stainless ball inside with a spring to hold pressure until high enough to satisfy the main injection pump then allows it to bypass.

Another real helpful tip for anyone trying to prime an A2 series truck with a 8.3 cummins, look at the injection pump while standing on the tire, inbetween the pump and head is a 10mm (most of the time) bolt that threads into a tapped nut, loosen it a couple turns, and prime away, you’ll get the air out of the system fast. Then snug it up, and continue to prime until you hear fuel going through the OverFlow Valve, it’ll sound nice and squishy