Kubota 902 engine, can’t start in cold (Edit: Probably not a "cold" problem)

sansbury · Oct 18, 2024

I have a Chine mini-ex (UHI UME18) with a Kubota 902 engine. Since the temps dropped into 30s overnight, I haven’t been able to get it started.

It cranks fine and I checked with a meter and the glow plug rail gets 12V.

I give it about ten seconds on the “heat” setting and then crank it. I was able to get it to start once but it ran very sluggishly and died after 30s or so.

If I crank for 10-20s it will fire once or twice but doesn’t catch. I get mostly white smoke but a puff of gray if it fires. Though the last attempt I wasn’t getting much smoke. I’ve tried with throttle at idle and maybe 1/4 open.

It has not really been below freezing in past 24h so I don’t think water could be frozen somewhere but who knows.

At this point I’m reluctant to keep going as I don’t want to run the battery out or burn out the starter. The battery still shows 12.2V and it’s cold and it’s a full size battery but I don’t want to waste it.

The dealer says he’s going to get a tech out to me sometime next week but if I could get it started sooner I’d be very happy.

Thanks in advance for any suggestions!

Roadworthy · Oct 18, 2024

Your battery voltage is a bit low. How much does it drop during cranking? Clean battery contacts and ground - 'tis the season. It's good your glow plug rail gets power. Do the glow plugs themselves? Are they actually heating or possibly defective? If it cranked only to run sluggishly it could be a lack of fuel or air though it sounds like fuel. How's your fuel filter? Does fuel flow freely from the tank? You'll probably need to bleed fuel lines after checking.

sansbury · Oct 18, 2024

Thanks.

The battery is brand new (20hr machine) and all very clean. I’ve cranked it a bunch of times now plus it’s been cold so it is probably just me depleting it.

How do I verify fuel flow and bleed lines? I’ve looked for troubleshooting guides/videos but haven’t found much.

Mike1955 · Oct 18, 2024

sansbury said:
Thanks.

The battery is brand new (20hr machine) and all very clean. I’ve cranked it a bunch of times now plus it’s been cold so it is probably just me depleting it.

How do I verify fuel flow and bleed lines? I’ve looked for troubleshooting guides/videos but haven’t found much.

If I were allowed to just guess, I would guess the glow plugs aren’t working. For what reason, I would not guess

sansbury · Oct 18, 2024

Mike1955 said:
If I were allowed to just guess, I would guess the glow plugs aren’t working. For what reason, I would not guess

I see 12V at the rail. What else should I check?

Mendonsy · Oct 18, 2024

Try waiting longer in the "heat" cycle before trying to crank the engine. Are you measuring the glow plug voltage while doing the "heat" cycle.

sansbury · Oct 18, 2024

Yes, 12V when key is put in position.

SPYDERLK · Oct 18, 2024

sansbury said:
I see 12V at the rail. What else should I check?

You need to find out if the GPs are taking current. Can you disconnect the wire feeding them and see if it sparks when you touch it back. The GPs may be burnt out.

sansbury · Oct 21, 2024

How difficult should it be to see the spark? I disconnected the lead and brushed it and didn't see anything, but the sun was bright so if it was small I might not have seen it.

I also tried to check a few things in the fuel system. I drained the water separator and there wa son water in it. It refilled after I tried cranking the engine. The fuel filter did not look plugged--just yellowish diesel color.

One other thing I noticed when I was running the glow plugs was a bit of a fuel leak right here. It wasn't clear if it was on the rubber hose side or the injector. I don't know if that's the cause of my problems but I'm assuming it's not supposed to do that....