Help!! Kubota excavator won’t start

[Vigo]

Well, the good thing is that you have ACCESS to that kind of info and are able to interpret it, etc. As you said, not a mechanic but for not being a mechanic you're able to operate at a pretty high level here where most people would just be stuck not being able to talk to the computer, i think.

So when you get the chance, verify that there is no injector pulse at the connectors. If there WERE injector pulse we'd either be looking at fuel pressure, or a compression problem. But you might already know that a compression problem is often detectable by ear because it will change the rhythm of the engine's sound while cranking. Besides, most 3 and 4 cyls will still start even with one dead cylinder, so it's just extremely unlikely to be engine internals.

So the pulse thing would send you one of two ways: It has no pulse=computer is not trying to run the engine, probably because it doesn't see crank or cam position/rotation. It has pulse=look at fuel pressure possibilities.

Considering you can read the computer already, maybe just check if you can see engine rpm while cranking, that will at least rule out something without getting your hands dirty.

 

[Jchonline]

Besides, most 3 and 4 cyls will still start even with one dead cylinder, so it's just extremely unlikely to be engine internals.

Thats kind of where I was going. Hard to believe it is an internal engine problem.

If it was a fuel/rail pressure problem that would throw an error. If an injector problem, should throw an error. See WSM below. I still think its electrical of some sort.

 

[lugbolt]

work shop manual makes the task a lot easier.

but in my opinion, it doesn't go into enough detail on how the CR system works, that is in the diagnosis manual-which is part of diagmaster.

 

[Beech123]

Thanks again everybody for the advice. I have ruled our cam and crank sensor, (by replacing like a dummy). I figured injectors weren’t opening and thought that could be the problem. Unless I bought bad sensors then that’s not it. Virgo can you explain to me again how to check pulse. Also I keep hearing diagmaster I’m assuming this is a software program. I haven’t found a diagnostic port anywhere. Any thoughts on location

 

[Vigo]

Injectors are usually 2-wire devices. Inside is really just one long wire wrapped around many times to make an electromagnetic coil and what you see coming out is both ends of that wire. Usually vehicles give the injectors power when the key is on, and it's usually shared from a common source (a single fuse). The computer has individual grounds for each injector, and gives the injector ground when it's time to open it.

So on most vehicles you would have power on one side of the injector connector, and no ground on the other side unless the engine is spinning. While the engine is spinning you should have a flashing/pulsing ground on the other wire. It's not practical to check it with a lot of multimeters, but it's easy to see it with a test light. So first you clip your test light to a ground and see which terminal of the injector connector (on the vehicle side of the harness, not the injector itself) has power with the key on. To see ground with a test light you hook its alligator clip to a power source, and it lights up whenever what you're poking with the stick is grounded. So you would then clip test light to power, poke test light into whichever side of the injector connector doesn't have power, and have someone crank it while you watch for pulses.

#37, 38, & 39 on that symptom chart irritate me..

"why doesn't the engine start?" "because it might cause pollution!". Well no shit, sherlock. And how much pollution does the kind of vehicle that can recover a broken excavator cause, when it's dragging an excavator that won't run because of an exhaust sensor?

 

[Jchonline]

Thanks again everybody for the advice. I have ruled our cam and crank sensor, (by replacing like a dummy). I figured injectors weren’t opening and thought that could be the problem. Unless I bought bad sensors then that’s not it. Virgo can you explain to me again how to check pulse. Also I keep hearing diagmaster I’m assuming this is a software program. I haven’t found a diagnostic port anywhere. Any thoughts on location

Pretty sure only Kubota repair facilities have access to Diagmaster……maybe someone can confirm.

 

[Beech123]

Injectors are usually 2-wire devices. Inside is really just one long wire wrapped around many times to make an electromagnetic coil and what you see coming out is both ends of that wire. Usually vehicles give the injectors power when the key is on, and it's usually shared from a common source (a single fuse). The computer has individual grounds for each injector, and gives the injector ground when it's time to open it.

So on most vehicles you would have power on one side of the injector connector, and no ground on the other side unless the engine is spinning. While the engine is spinning you should have a flashing/pulsing ground on the other wire. It's not practical to check it with a lot of multimeters, but it's easy to see it with a test light. So first you clip your test light to a ground and see which terminal of the injector connector (on the vehicle side of the harness, not the injector itself) has power with the key on. To see ground with a test light you hook its alligator clip to a power source, and it lights up whenever what you're poking with the stick is grounded. So you would then clip test light to power, poke test light into whichever side of the injector connector doesn't have power, and have someone crank it while you watch for pulses.

#37, 38, & 39 on that symptom chart irritate me..

"why doesn't the engine start?" "because it might cause pollution!". Well no shit, sherlock. And how much pollution does the kind of vehicle that can recover a broken excavator cause, when it's dragging an excavator that won't run because of an exhaust sensor?

Ok thanks for the thorough explanation. I really appreciate it. There is a ton about green energy that makes no sense!!

 

[Vigo]

Yes, there are some goofy forms of logic involved. Like, exhaust sensors CANT make your engine not run, but they can make the COMPUTER make your engine not run. Uh, what?

Because manufacturers have to warranty certain exhaust components for certain periods of time. So even though you could take a sledgehammer to all the sensors on your exhaust and the engine itself SHOULD be perfectly happy, the manufacturer will program it to not run if the exhaust sensors are bad, because they don't want your perfectly happy little engine to melt down the filter or catalyst that they would then have to warranty, when they could warranty just the sensor instead. Or heck maybe even say the sensor isn't covered by warranty and make you buy it! There's no legitimate reason for the exhaust sensors to make the engine not start, other than protecting the manufacturer's pocketbook from warranty claims.

But they could very well be the source of your problem according to that chart..