2013 M8560 Slow Starting

[Tx Jim]

Normally it doesn't get or stay below freezing very often in the Winter where I live. As I stated my M7040 starts fine above freezing temperaturs without the need to manually activate the GP's. YMMV

 

[jkwilson]

First, thanks for the input so far.

Busy weekend, so I was troubleshooting as I used it. Fully charging the battery produced no improvement. Running a 200A boost charger didn't noticeably change cranking speed or improve the starting performance.

I'll start checking the fuel/water separator next time I use it.

 

[jkwilson]

I may have found the issue.

Putting hay out yesterday near 0 degrees and the tractor wouldn’t throttle up. Headed for the barn and it died 3ft before I could close the door behind it.

So I ended up working on it in single digit temps. Cold weather and a Diesel had me suspecting a fuel delivery issue even though it was winter fuel with additive.

Pulled the outlet of the lift pump and found sputtering and spitting. Took the fuel/water separator apart to see what was going on. Nothing amiss, but I tried to replace the element (more on that later) anyway, and I think I found the problem. When I first checked the housing it had fuel on it. As I tried to reinstall the housing, I found that right as it tightened, the threads popped loose so I couldn’t get the housing tight. I’m certain the leaking housing was the cause of my issues yesterday, and I’m a little suspicious that maybe it was the cause of the hard starting.


Back the separator element. The new element, the correct Kubota part, is too small to fit over the nipple on the tractor. Lining the two elements up, the hole is very slightly smaller on the new one. An angled pick catches on the joint. Anybody come across this?

 

[JerryMT]

Tractor started nearly instantly when I first got it. Less than 500 hours. Fuel filter has less than 25 hours on it.

Out of the blue, the tractor became slow to start. 3 or 4 rounds of cranking, maybe 7 or 8 seconds each, and then it will start. What puzzles me is that it doesn't matter whether it is cold or warm, it still exhibits some slowness. Glowplug light comes on if it's cold enough, and I wait for it, but it seems to make no difference. I've left the block heater plugged in for hours and it exhibits the same behavior. Still does it when air temps are in the 70s.

Even when working the tractor, it is slow to restart if you stop to get out. Maybe takes 2 or 3 rounds when it has been running.

Don't see any smoke to speak of when cranking.

Starting aside, the thing runs like a top once it goes. No smoke while running. Fuel from a fresh, reliable source. No leaks. Once the tractor starts, it immediately runs fine with no loping or smoke to make you suspect fuel delivery issues.

My only suspicion would be the battery, and this is only because one day over the winter I started it after the battery maintainer had been plugged in for a couple of days, and it started right up. The maintainer was just plugged in because I tend to run the tractor for short spells during the winter and I wanted to be sure the battery was fully charged. I hadn't seen any battery issues.

Cranking speed sounds normal all the time though, so I'm puzzled.

Appreciate any advice.

"Don't see any smoke to speak of when cranking."

That makes me suspicious. If the injectors are fueling, you should see some white smoke. I wonder if you have some sort of drain back so the fuel lines upstream of the injectors are dry? Do you have a lift pump and if so, is it pressurizing the fuel to 2-4 psig? Also make sure that your air filter is clean.

 

[lugbolt]

M8560, you won't see any smoke when cranking. The DPF and DOC catch a lot of the "smoke"-even the unburned fuel "smoke". This characteristic also follows across the board to most if not all of the DPF/DOC equipped engines.

Do you have any codes or check engine lights showing? Or have you ever had anything showing? Has there been any history that we don't know about? Flooded? air filter issue? Turbocharger failure? Has the regen been too frequent at any point? Etc?

Diagmaster would find the issue quickly if the tech using it knows what to look for.

When's the last time the spin-on fuel filter was replaced? Have seen those neglected entirely too often. The "filter" in the bowl is a pre-filter and separator, there is another one (spin-on) that catches the fine stuff that gets through the pre-filter/separator assembly. It's a bear to get to the spin on filter if you have a loader. Not impossible but not easy enough for people to get motivated to change it often enough, IMO.

 

[jkwilson]

The root cause of the problem was poor seal at the fuel water separator causing the line to drain back to the tank and the lift pump to struggle to prime. It appears that an O-ring was either swollen or the wrong size, leading to the previous owner damaging the threads on the separator bowl when trying to install it.

I changed the bowl and all the O-rings associated with it. Everything went together smoothly. After the replacement, I opened the cab door and turned the key on. After about 30 seconds to allow the fuel pump to prime, I engaged the starter and the tractor started almost immediately. I've used the tractor half a dozen times since, and when warm it starts virtually as soon as the starter engages, and when cold it starts within a few revolutions of the starter.