953B with 3116. Wasn't given a complete serial number but the machine prefix is 5MK and I believe the engine prefix is 4TF. A guy called me saying his 953B died. Only way machine runs is if someone continuously runs the fuel primer. I haven't been to the machine yet to confirm his complaint or look for obvious issues. My knowledge on 3116's is limited but I do have full access to SIS to read system ops. Based on info given, sounds like it could be something in the transfer pump isn't functioning properly. Not sure if a check valve(s) is stuck, worn piston/cam, or just a simple o-ring. I'm looking to get some insight or direction to troubleshoot from people with more knowledge/experience on these engines before I go out there this week. Thanks
Injectors arnt sealing to the cups no more. Pull the return line and put a clear hose on it if its full of a absured amount of bubbles thats the trouble. Would be my first check
Thanks, I’ll will definitely check that out when I get to the machine
if it runs wile you are pumping the priming pump i would not think it would be the injectors the supply pump is located in the governor assy you can replace the piston and check valves. I would check the check valves and piston for damage
Start by checking fuel pressure at the secondary filter. Should be about 20 psi at idle and over 45 psi revved up. Then test return fuel for air bubbles. Could be transfer pump check valves. Could be injector seats but if it runs while hand priming I would think more likely transfer pump.
Update for anyone wondering Pulled apart the transfer pump and found some light scoring on the piston but no smoking gun upon initial glance. Installed new piston, pump, inlet check valve and inlet fitting. Primed system and ol' girl fired right up. Ran engine rpm's up and down to make sure engine didn't stall out coming off high idle. Sounded really good for an engine with 12k hours. I inspected the old parts after the machine was done and found there was broken check valve inside the piston. The little flap in the piston wasn't seating while pumping, allowing the fuel to flow backwards.
Glad it wasn't a major problem and you could fix it.