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Old 06-18-2011, 02:24 PM   #1
chad95
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Location: menomonie,WI
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Default L2550 wont start

L2550 wont start without hint of ether. Seems that the injects wont work until tractor is running. Tried new fuel filter,bled to the injectors and tried it with one injector out of cylinder to see what it was doing.Any help would be great.
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Old 06-18-2011, 06:09 PM   #2
Theekillerbee
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Default Re: L2550 wont start

Sounds like a compression issue to me. It could also be a clogged injector that is not atomizing the fuel enough to get it to fire. Not sure how to run a check on the injector, but you can get a compression tool and see how much you have.
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Old 06-19-2011, 06:45 AM   #3
284 International
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Default Re: L2550 wont start

What was the injector you pulled doing?

There isn't anything about an injector that "knows" whether the engine is running on its own or being spun by the starter. It may be that your injector pump is bad, or out of tolerance. You may be running on two out of three cylinders, and the ether lets you get it going.

As thekillerbee mentioned it might be a compression issue from worn rings or something else, but if you have demonstrated that you have a dead injector, that is the logical place to start.

Try pulling another injector. Also, try pulling the line off, or just loosening it, where the high pressure line connects to an injector, Fuel should pulse out of there when the engine is cranked. If you don't have injector function, but have fuel pulses at the line, then it's your injector. If there is no fuel pulse, then it is upstream somewhere, at the pump, most likely.

Is there any back history of this machine's symptoms?

How many times have you used ether? You're asking to break things and wreck the engine on these little diesels when you do that, just so you know.
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Old 06-19-2011, 01:41 PM   #4
chad95
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Default Re: L2550 wont start

Injectors are new as is the fuel and air filter. Engine also seems to die or run out of fuel if you decelerate quickly.Haven't got the piece to do a compression check yet but might find one tomorrow. Engine is old and was not maintained prior to my ownership but has always ran good. Hope it isnt rings but could be for its age. Any other tests to try? Injection pump seems complicated but I am fairly compent as I have done lots of other motorsports just not alot of diesel experience.
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Old 06-19-2011, 01:56 PM   #5
284 International
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Default Re: L2550 wont start

If the injectors are new, you need to know if fuel is reaching them. Crack the injector lines and see if fuel spurts out. Make sure the engine is at full throttle when you do this.

Why were the injectors replaced?

Stop using ether to get it running, hopefully you haven't broken anything yet.

It's kind of tough to diagnose without more information about the questions already asked.... Try the things suggested and we'll see if we can give you more things to try.

The diesel engine needs air, fuel, and heat, in the form of compression once under running conditions, to operate. If any of those things aren't adequately provided at the right time, the engine won't work. If you have clean fuel reaching the pump, which your new filter and proper bleeding should have accomplished, we need to see if it is reaching the injectors.

So, crack the lines a bit and see if you get fuel out of them when you crank the engine. If fuel is coming out, then your pump is at least moving fuel. If one or more lines doesn't have fuel, we can start isolating problems at the pump. A little "percussive maintenance" (basically gently rapping it with a hammer) may free up the plunger for the dead cylinder.

Since you don't have the equipment to do a compression test ( a regular automotive one will not work, you need a diesel specific gauge) you may as well start with what you can test. If you discover you need rings, you are stuck doing a rebuild. You'll still want to test the pump and injectors anyway. Get it out of the way first. It may still end up being an internal motor problem, but it's logical to proceed from the outside in.
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Old 06-19-2011, 04:16 PM   #6
chad95
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Default Re: L2550 wont start

When I had it running I cracked the injectors at the top of the injectors themselves and could tell that each cylinder was effected as I went back and for about 6 times for each cylinder but when the tractor is off it doesnt seem to pump fuel to the injectors but fuel is pumped to the injector pump from the transfer pump. I replaced the glow plugs filters and injectors when this problem started just figuruing that a 25 year old tractor could use it no matter what but it has not helped if anything the throttle idle down and dying(sometimes)seems to have got worse. I know the ether can kill it so I need to figure this out but why would it only pump when running (need vacuum from engine?)
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Old 06-19-2011, 05:07 PM   #7
chad95
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Default Re: L2550 wont start

I should add that this just happened all at once not like rings getting bad and finally failing but more like the pump has failed or slipped time. I also always use the manual shut off any chance that can fail inside the injector pump area?
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Old 06-19-2011, 05:54 PM   #8
284 International
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Default Re: L2550 wont start

Injectors work by reaching a certain predetermined pressure and then "popping," which sprays the fuel through the tiny holes and into the combustion area of the engine. These are pressures between 1700 and 3400 psi. Even if the engine were pulling a complete vacuum (which it won't, of course) you're going to see under 15psi at the injector-insufficient to make any difference. Plus, it's at the wrong time in the cycle to make any difference, since the injector will go off at nearly full compression, advanced similar to a spark ignition engine's timing.

I don't know about Kubotas, but some diesel engines have injector pumps that are not lubed by engine oil, and have a reservoir internal to the pump itself. Here is an example of a Shibaura pump of this style. (Third post down.)

It sounds like you're having issues at the pump to me. Check the linkages and make sure there is nothing binding or worn.
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Old 06-19-2011, 06:19 PM   #9
chad95
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Default Re: L2550 wont start

I will check that out tomorrow asap and see what I can figure out. Can I take that pump out by taking four bolts out of the top and just lift it out or is there more to it?
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Old 06-19-2011, 07:38 PM   #10
284 International
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Default Re: L2550 wont start

I don't know about that machine specifically, since I've never even seen an L2550.

The pumps I've seen or messed with required pulling a cover and then removing the linkage for the governor, removing the mounting bolts, then clocking the pump, fiddling with the rack and finally sliding it out.

How are you able to start the tractor? Once it's going, does it work fine at full throttle? Is it just when throttling down that it wants to die? I'd look closely at everything going on there before trying to pull the pump off. There's not anything really user-serviceable in there anyway.

Investigate the shutoff linkage and throttle linkage. It's possible something is amiss or broken there.

Do I understand you correctly that if you pull the injector lines off and crank the engine no fuel comes out? If so, try gently tapping on the pump with a hammer as you crank the engine, to see if you can free a stuck plunger.

I am still not totally clear on the symptoms you're experiencing. I've put some questions all together, though some are repeats. Hopefully others with more knowledge than me will chime in, too:

1. Does the tractor run ok once started? Normal power, rpm, etc?

2. What color, if any, smoke do you see when running and starting up?

3. Will it run at part throttle, and/or idle?

4. When you say it wants to die when the throttle is reduced, what happens if you go from full throttle to half throttle?

5. What happens at the injector lines when they are removed and you crank the engine, with the throttle set at full?

6. Is the reduced throttle shut-off of the engine intermittent, or consistent?

Good luck, you'll get it figured out. Post back with what information you can so we can help.
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