911 - I Jinxed Myself - Tractor lost power cutting hay. Want to verify Tec analysis

[powerscol]

Well at 810 hours I was not expecting this. I posted in another thread as to how dependable my tractor was.

Cutting hay yesterday. Had been running about 6 hours, took a potty break and fuel up (tank down to 1/2) while at home. Went back out ad had run another hour running my PZ170 drum mower, when unit lost power and died. I tried to restart but no go. I did have a slight vibration just before issue, but thought it was a drum mower blade issue - not.

I changed the fuel filter, but it still looked new. I was able to restart after letting it sit for a bit, but it was running very rough with little to no throttle response. Managed to creap it out of the pasture in low range. Engine running very rough. No overheating issues.

Bobcat tec out AM from dealer. He is not a tractor expert, but checked with the Doc back at the shop.

Checked fuel filter for flow - good
Checked lift pump - flow but not large when cranking - it did pulse, but nothing big
Cracked injector line on top of engine - no large spray
Cracked line right at injector pump - large spray expected - none occurred


Question - how much of a spray should come out of the lift pump?
Question - if lift pump weak will injector pump still produce large spray

Tec check with folks back at the dealer and though if lift pump not working properly, injector pump would not deliver pressure.

Lift pump is about $40 and injector pump is about $1100. Considering having both overnight shipped. Hay down and only a small weather window. There is a hefty restocking charge. so if one part not needed I need to consider keeping it for the future. I.E. if it is the lift pump, do I keep the new injector pump of pay the 25% restock charge. Or do I go ahead and have them replace both?

They are going to haul it in this afternoon.

I also asked them to drain and flush the tank, just in case it was caused by bad fuel.

Thoughts?

 

[Industrial Toys]

I'm just guessing it's in the lift pump side. They fail. Why would your injector pump fail?

Not sure if some electric (is that what your talking) lift pumps are on demand. So, if you crack a line, they may not make much pressure, but there should be flow. Electric lift pumps are always so much nicer to troubleshoot as you don't need to be cranking the tractor.

Is your fuel system gravity fed or suction? Suction system can suck air and be very hard to locate the problem.

Also, and I never figured why this is so. Some Diesels need to be bled from bottom to top if they run out of fuel, or you open the fuel system. Some (Thankfully) you just crank and they go, or it sometimes helps if you make sure the lift pump is primed.

 

[powerscol]

I'm just guessing it's in the lift pump side. They fail. Why would your injector pump fail?

Not sure if some electric (is that what your talking) lift pumps are on demand. So, if you crack a line, they may not make much pressure, but there should be flow. Electric lift pumps are always so much nicer to troubleshoot as you don't need to be cranking the tractor.

Is your fuel system gravity fed or suction? Suction system can suck air and be very hard to locate the problem.

Also, and I never figured why this is so. Some Diesels need to be bled from bottom to top if they run out of fuel, or you open the fuel system. Some (Thankfully) you just crank and they go, or it sometimes helps if you make sure the lift pump is primed.

Its a manual lift pump and issue started with good fuel flow.Nothing electrical we can think of. I changed the filter after the issue and Tec fully bled the system. Fuel is gravity flow as far as I know. but with engine off there was good flow into the fuel bowl and at the lift pump.

There is an electronic sensor located on the lower forward part of the injector pump, but made no difference if unplugged.

Thanks for the thoughts

Its a 2011 m0del . I know there was issues with the Kioti injector pump from around then. Bobcat is a clone of the Kioti. (made by same parent company)

 

[Industrial Toys]

Is that electrical connection to the injector, not the fuel shutoff solenoid by chance. I came accross a machine recently where that internal solenoid seemed to be sticking.

 

[the old grind]

Sequence of events causes me to imagine that fuel top-up (no lines open or filter changed) added contaminant(s) that took a whole hour to work to the pump/injectors.

I'd bleed each and every one hoping to get rid of whatever might have passed the old filter and thus wasn't seen in the new one. Too much happening too suddenly to sound like a mechanical failure. Dare I suggest you didn't top up using a Mister Funnel? IMO their filtering prowess is unmatched and worth the few oz of spillage that's likely.

I could be seriously wrong about lift pumps, but highly doubt that an injector pump would ever require more priming pressure than available from a gravity-fed supply. Rough running is a horribly vague symptom from which to discern a problem's source. One weak cylinder can make a good sized diesel shake like you'd expect it to fall apart in a moment.

btw, When I said 'bleed', that could be up to and including to disconnect all lines and crank away to flush. I'm either all wet, or something might have snuck around the tests and re-dos and is yet lurking in or between pump and injectors.

 

[powerscol]

Sequence of events causes me to imagine that fuel top-up (no lines open or filter changed) added contaminant(s) that took a whole hour to work to the pump/injectors.

I'd bleed each and every one hoping to get rid of whatever might have passed the old filter and thus wasn't seen in the new one. Too much happening too suddenly to sound like a mechanical failure. Dare I suggest you didn't top up using a Mister Funnel? IMO their filtering prowess is unmatched and worth the few oz of spillage that's likely.

I could be seriously wrong about lift pumps, but highly doubt that an injector pump would ever require more priming pressure than available from a gravity-fed supply. Rough running is a horribly vague symptom from which to discern a problem's source. One weak cylinder can make a good sized diesel shake like you'd expect it to fall apart in a moment.

btw, When I said 'bleed', that could be up to and including to disconnect all lines and crank away to flush. I'm either all wet, or something might have snuck around the tests and re-dos and is yet lurking in or between pump and injectors.

He was very puzzled/concerned by the lack of flow in the injector lines, either at the pump or at the head. Fuel just did not come out. The old filter had about 100 hours on it and appeared to be in new condition when removed. I am tempted to drain the tank and add fresh fuel from another source.

 

[deezler]

Its a manual lift pump

Huh? Not sure what that means. If it is a pump, it is electrical. For $40, I would start there. But they are easy enough to test, just take a fuel line off after the lift pump, and put 12V to it. Does it flow with authority? Most mechanical injection pumps can suck fuel just fine to keep an engine running, but if the system is designed with a 12V low pressure lift pump that fails, there is now an obstruction in the fuel path.

 

[powerscol]

Huh? Not sure what that means. If it is a pump, it is electrical. For $40, I would start there. But they are easy enough to test, just take a fuel line off after the lift pump, and put 12V to it. Does it flow with authority? Most mechanical injection pumps can suck fuel just fine to keep an engine running, but if the system is designed with a 12V low pressure lift pump that fails, there is now an obstruction in the fuel path.

There are no electrical connections to it. Its part 18 here and runs off the fuel cam shaft Bobcat Genuine Parts Catalog – Official Bobcat Company site

 

[Industrial Toys]

I'm surprised that any modern tractor has a cam driven lift pump.

 

[the old grind]

My '67 Dodge and current '98 Terramite (both gas) would plug at the tank fitting. The truck might stall in an intersection, and the non-sync 'granny' 1st gear would get me to the far side using the starter. The T5C plugged the same way, like when I picked it up and it wouldn't start to load onto my trailer. I could always huff the restriction free, and never sought a cure for a once-a-year-and-forgotten little hitch either place.

Often enough a 'slow' flow is just shy of enough, what the tec saw and surmised. Can we blow out disconnected lines too, including into the tank first to stir things up to be drained?