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

[sansbury]

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]

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]

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]

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]

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]

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]

Yes, 12V when key is put in position.

 

[SPYDERLK]

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]

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....

 

[TractorTYMe]

Your red circle is fuel return from the injector. On my example is where the glow plug wires are hidden beneath.

 

[SPYDERLK]

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....

The GP draw should be a few amps so a spark should be visible pretty easy IF you get out of the dazzling sunlight. The easiest thing would be to wait for twilight when you have just enough light to see what youre doing. Remember to have the key in the proper position and "strike" the wire across the terminal. Should spark. -- Other methods >Does your meter have an amps and an ohms function? Do you have clip leads, probes, ... both?

 

[sansbury]

I have a multimeter with clips and probes.

 

[sansbury]

I’m getting readings of 2-3 ohms from battery negative to each plug.

 

[SPYDERLK]

I’m getting readings of 2-3 ohms from battery negative to each plug.

That sounds good. Thats a 12v/3or2 = 4 to 6A. You should get a visible spark.

 

[sansbury]

Update: it’s been unseasonably hot (pushing 80 midday) so thought I’d try again in case it was just the cold causing problems.

I cranked the engine hard (15-20s) a couple times and managed to get it to catch and run once for a minute or two. It sounded a little weak but figured I’d just let it sit and charge up the battery. However it died again.

I've tried twice and it continues to almost run but I am starting to think this is pointing to a fuel problem since the air intake and filter seem clean as new.

The inline filter doesn’t look clogged, but should I replace it just on principle, or is there anything else I can do to check it?

Anything else? The dealer is supposed to be sending somebody but they are also giving me a bit of a runaround so I am motivated to find a solution…

 

[SPYDERLK]

Update: it’s been unseasonably hot (pushing 80 midday) so thought I’d try again in case it was just the cold causing problems.

I cranked the engine hard (15-20s) a couple times and managed to get it to catch and run once for a minute or two. It sounded a little weak but figured I’d just let it sit and charge up the battery. However it died again.

I've tried twice and it continues to almost run but I am starting to think this is pointing to a fuel problem since the air intake and filter seem clean as new.

The inline filter doesn’t look clogged, but should I replace it just on principle, or is there anything else I can do to check it?

Anything else? The dealer is supposed to be sending somebody but they are also giving me a bit of a runaround so I am motivated to find a solution…

Sure sounds like a fuel problem. Could be a blockage in the tank, or the filter, or water. See if the line from the tank to the filter flows well.

 

[sansbury]

See if the line from the tank to the filter flows well.

Dumb question but what would be the best way to do that? I don't know a lot about these diesels but I know how to use tools carefully and follow instructions

 

[SPYDERLK]

Dumb question but what would be the best way to do that? I don't know a lot about these diesels but I know how to use tools carefully and follow instructions

Understood. The problem is I dont know your machine. I do have some kubotas but no reason to think theyre all the same. Mine have the tank at higher level than the filter and fuel flows by gravity through the filter to a lift pump. Can you ID the fuel line going tank to filter? If so disconnect it at the filter. If it gushes youre good. Drain your tank into a ready catch can to assess later. If it only dribbles or drips there is something blocking flow, either at the tank outlet or in the fuel line. Stop there and post back.

 

[sansbury]

Understood. The problem is I dont know your machine.

Fair enough and I appreciate your trying

I suspect this is Diesel 101, mostly.

As best I can tell, the fuel siphons from the top of the tank, then goes down through the water separator, up to the little plastic inline filter, back around to something about the size of a tuna can with some wires, then from there to a larger fuel filter that looks like a small oil filter, then back down somewhere else. Not sure if the thing with the wires is an inline priming pump or something?

I did try draining the separator and it did eventually refill after a crank or two.

 

[SPYDERLK]

Fair enough and I appreciate your trying

I suspect this is Diesel 101, mostly.

As best I can tell, the fuel siphons from the top of the tank, then goes down through the water separator, up to the little plastic inline filter, back around to something about the size of a tuna can with some wires, then from there to a larger fuel filter that looks like a small oil filter, then back down somewhere else. Not sure if the thing with the wires is an inline priming pump or something?

I did try draining the separator and it did eventually refill after a crank or two.

That setup is alien to me. Are the fuel lines rubber- you can pull off the nipple or reconnect at will? If so pull off the line leaving the big filter. Does fuel flow? Turn on ignition to run the "pump". Any change?