Engine dies under load when cold

[Jetexas]

I have a Kubota Z482. It was brand new when I installed it 2.5 years ago, and it has maybe 40 hours on it at this point.

The fuel goes from the tank to a primer ball to an inline filter to a bowl filter and then to the injection pump.

It's self-priming and always start right away. Purrs like a kitten.

However, unless I let it run for a few minutes, it dies under load. Once it's warm, it does fine.

For example, if I turn it on cold and start backing out of the slip, if it doesn't die when I first hit reverse, it will die when I click back into forward.

Also, if I turn it on cold after sailing and start motoring in, it will run ok for a couple minutes and then start sputtering. If I kick it into neutral, rev it up for a second, then put it back in gear, it's fine and will run normal all the way home.

I just changed the filters, but that didn't seem to change the problem at all. Any other ideas?

Like I said, if I let it warm up a couple minutes it's fine, but I know that's not the way it's actually supposed to work.

[captainKJ]

diesels need to warm up for a couple of minutes. You engine is fine. It also depends on how cold the water is at the intake????? for example in Florida you need less time to warm an engine than in maine.

[Stu Jackson]

Have you removed the screen in the fuel pickup line in the tank? Have you checked the fuel filter screen?

[Jetexas]

Originally Posted by Stu Jackson

Have you removed the screen in the fuel pickup line in the tank? Have you checked the fuel filter screen?

No. I have not checked any screens. I'll have to look for those.

[shakey doug]

Your problem has all the hallmarks air entering the fuel system some where close by the engine.

[ausaviator]

When you start a diesel car or tractor for example, it is capable of running at close to full RPM, almost immediately. Would suggest that the behaviour or your engine is not normal.

[Ex-Calif]

Originally Posted by Jetexas

I have a Kubota Z482. It was brand new when I installed it 2.5 years ago, and it has maybe 40 hours on it at this point.

The fuel goes from the tank to a primer ball to an inline filter to a bowl filter and then to the injection pump.

40 hours in 2.5 years is not much running. How much fuel have you put through the tank? I suspect not much.

Current quality of the fuel would be on my list. Clean the fuel system including the tank (stuttering after running a while) and consider replacing the fuel. Also I would definitely check any o-rings in the system for drying out and leaking air in. In fact I would replace them all anyway.

Also after 40 hours since new I would check/adjust the valve clearances and maybe raise the idle RPM a hundred or so.

A longer warm up wouldn't hurt, in gear at 1000 rpm or so while tied at the dock. And finally I would plan to run the engine hard at least once a month. 2500+ rpm motor sail for at least 30-60 minutes.

I don't think there is anything much wrong with your engine that a little PM and hard running won't cure.

[Boracay]

My guess would be that the primer bulb is somehow slowing the flow of fuel to the engine.

If it were me I'd try squeezing the bulb just before applying power. May give a clue to the solution.

[Bash]

Folks, were talking about a 2-banger here. Maybe 13 horses?

An engine like that deserves a good warmup, especially if you're only running it 16 hours per year.

Ex-Calif's advice about fuel quality is worth reading again.