Our kohler/John deere 70kw generators just had their 500 hour service by contractors to keep their warranty valid. I oversaw the operation. After changing fuel filters etc they bled the fuel system on the filter bleed screws and using the fuel lift pump priming handle. They didn't bleed all the way upto the injectors. However both generators started and ran without any fault on completion of the service. We then returned to using shore power once the generators had ran for a while, the next day both generators stalled on start up and we've had the problem intermittently for the last two weeks. After stalling they always start second time without fail. The control of the generators is remote from an MPA screen which we use for most systems onboard. The skipper has emailed them to come back but in the meantime I've been trying to find the cause. I've bled the system at the filters again to get any air out, checked all fittings to make sure they are air tight, we know the fuel is good because it's been spun in the centrifuge several times now. I'm starting to think there could still be some air in the lines between the filters and injectors? Is this possible that air can stay in there for that long and cause the engine to stall even after we have ran the generators for a good 10-20 hours each since the service? I can understand why they didn't initially bleed at the injectors because it's pretty tight to get in there, but I'm starting to think this could be the problem. I don't want to get to involved to the point where we invalidate our warranty. Also the contractors may refuse to do anymore work because we've fiddled with them since they serviced them a week or so ago! Has anyone got any ideas on what the cause might be aside from the obvious? Thankyou.