Injectors on a Kubota 3 cylinder engine.

[scooby1]

I know it's not cars but just wondered if anyone could give me a ball-park figure for the cost of having the three injectors serviced on my Kubota 18hp ride-on lawn mower please.

Thanks for any advice.

 

[Burnerman]

I guess this will be the indirect injection engine, with the 3 glow plugs?
The first job is to find a diesel specialist who is familiar with the traditional type injector.......I had some done 6 years ago (Lister injectors) and basically all they need to do is to check the spray pattern and the potential to dribble.
If there's a problem, the injector can be ultrasonically cleaned and then retested. It cost me £40 for each test, plus £60 for the faulty one to be sorted.
What problems are you getting? I've never found these engines to be smoke free or quiet, and they are reasonable cold starters without being brilliant.
John

 

[scooby1]

Hi Burnerman, and thank you for your reply. Yes, it is the indirect 3 pot with the glow plugs. I have found that one of the glow plugs is u/s and so will have to replace that. But I thought that maybe servicing the injectors might help things a bit.

I went to start it a couple of weeks back and discovered that it was a bad connection why the starter wouldn't turn the engine over so sorted that out. But she still doesn't want to start. She fires on one pot and coughs a bit of white smoke out but then nothing.

I have had the injectors out and spun her over just in case there is excess diesel in the pots and even tried putting some warm air into the inlet manifold with an electric paint stripper but still she won't start. Going to get the new glow plug and fit that and try again but the next job is probably the injectors. I should say that she started O.K. when she was put away last Autumn.

 

[Burnerman]

The engine should start well enough, but only if the glow plugs are good.....it could be a shrewd move to replace them all - especially if you can get replacements anywhere but Kubota! Look for about 1 ohm resistance on each one.
Certainly an injector clean can do no harm, but the white smoke is unburnt fuel, or lack of pre heating so I'd sort that first.
Does your machine have the two plastic filters? Do change those too.
How many hours has the engine done - do you know?
John

 

[scooby1]

Thanks again John. All good advice there. The more I read what you have written the more I think it is the duff heater plug. Yes, I will change the two filters. The machine is a 1998 and has done 1056 hrs. David.

 

[Burnerman]

If it's the machine I'm thinking of, with one filter after the tank and then another after the electric fuel pump, do prepare for a sleeve full of diesel when you change the first filter
Saves on deodorant, I suppose!
These engines also like a good battery to turn them over smartly.
Be lucky! Excellent machine, and yours has done little work. If it's a hydrostatic drive, make sure you are sitting down when you price the hydraulic oil
John

 

[scooby1]

Thanks again John. Point duly noted about the filter change. I am surprised about the price of oil for the hydro. I buy oil for the 3CX torque converter and that isn't too bad. Maybe it's different oil. Thanks - David.

 

[montyhound]

Hello John.

You have been chatting with my mate David who has been helping me with a problem involving a Kubota D722 diesel engine.

My Kubuta G1900 tractor mower ( 1056 hours and regularly serviced by myself from new in 1998 ) was running just fine up to the end of last year albeit it was getting a bit hard to start.

This year it won't start at all. It cranks over with a bit of smoke and sometimes coughs but won't run even with a squirt of ether into the inlet manifold.

David identified a faulty glow plug and I replaced this with a new NGK YE01 but this hasn't helped.

I have what seems like good fuel flow from the fuel pump through to the injector pump block when the ignition is switched on but the fuel shut off solenoid is working only intermittently and even in the position where I think it should be open there is little or no fuel coming out of the pipe running to one of the injectors ( which I have loosened and rotated for the purposes of this test ) when I am cranking the engine over.

I have a couple of vintage tractor owning friends who are suggesting that the timing ( valve or injector pump ) may have jumped and would be grateful for your thoughts.

Regards

Richard

 

[Burnerman]

Hi Richard
I think the first thing you need to do is to sort that fuel shut off solenoid.....when the ignition is on, there should be 12v to the terminal on the top and this needs to remain constant until you switch it off.
Whether the injector timing is accurate or not shouldn't interfere with the high pressure delivery of fuel to the injector, and with the pipe loose the fuel should squirt out wholesale.
There really isn't anything you can do to the injector pump other than help it by keeping the filters clean, I'm afraid.
Can you post a pic of the pump, showing the stop solenoid please?
John

 

[montyhound]

Hello John and thanks for your reply.

I'm now certain that the problem that I had with the fuel shut off solenoid earlier today was because I had taken off the tin work and seat from the back of the tractor mower and the safety feature associated with no weight on the seat was cutting power to said solenoid.

Mice had got the rubber gaiters on either side of said solenoid some years ago and I have just rigged up a cloth replacement to keep dirt out of the guts of it which seems a very simple bit of kit and now seems to be working okay with the seat back on and wired in.

I haven't yet changed the two in-line fuel filters but am happy that fuel is being delivered to the injector pump block from the lifter pump when the ignition is switched on and I have disconnected the rubber fuel line for the purposes of this test.

Having disconnected one of the metal fuel pipes to the injectors I am concerned that little or no fuel is being ejected from the union when I crank the engine over and the fuel shut off arm on top of the injector pump block is in what should be the open position.

Battery now on charge.

Regards

Richard x

 

[montyhound]

PS - I'm not familiar with how this site works and downloaded a photo earlier but this is not showing against my last message.

Richard

Kubota G1900

• montyhound
• 25 Feb 2015
• 1

Injector pump issues

 

[Burnerman]

Is the stop solenoid under all the tape on the right?
For testing purposes, bypass all of the safety interlocks and apply 12v direct from the battery, just to keep the solenoid open.
When testing for fuel, keep the throttle open fully and crack open the nuts on top of the injectors.....they won't open if fuel can escape.
Can you be sure the injector ump is actually turning? Bit of a corny question, I know......!
John

 

[scooby1]

Morning John and thanks for helping my friend Richard out. My World is tractor, diggers etc. so not conversant with these little diesel engines but obviously understand the principle. The electronic stop control is under the black tape in Richard's photo. but I assume that the solenoid operates a mechanical linkage to the stop control on the injector pump. If that is the case then would it be better if Richard just disconnected the linkage and made certain that the stop control is in the run position on the pump.

Another thing I have thought about is that on rotary injector pumps there is very often a small gauze filter where the fuel delivery pipe enters the injector pump. Would you know if there is one on this machine ? I am assuming that it is a rotary pump.

One thing that does confuse me slightly is that Richard says he has fuel getting to the injector pump when he switches the ignition on (as you would expect as long as the stop control solenoid is working correctly) If that is the case then why can't he get a decent amount of fuel at the injectors when cranking the engine over ?

At one stage I thought it was a timing issue and suggested he took the rocker cover off to check valve movement. He now tells me it is timed with helical gears but I have suggested to him that he gets an exploded diagram of the engine just so that he can see more detail.

Thanks again - David.

 

[Burnerman]

Hi David
I'd like if possible to see the stop solenoid under the tape.....some types have a steel pin that retract with the ignition on, allowing fuel through, some operate a lever external to the pump and some are actually operated by vacuum!
Either way, that side of the system needs to be disabled until the engine is running - it can be reconnected later.
So, we are happy that diesel is being supplied to the injector pump but it doesn't seem to be getting any further, so to me either the fuel is still being mechanically shut off or the injection pump is faulty, god forbid.
The other scenario is that the injection pump isn't actually turning due to drive failure which I guess is by gear or chain......sorry I don't know which as I haven't had the engine dismantled that far.
I can't comment on any internal filters in the pump - the machine has two filters anyway so that should be enough - unless there has been water contamination at some time. Maybe there's an exploded diagram on the net somewhere.
Incorrect pump timing would definitely cause poor running or non start but so long as the pump is actually spinning it should still work......that's how I see it anyway!
I'd class the pump as being an in line type - rotary pumps having outlets on the end rather than the top.
Stay in touch
John

 

[montyhound]

Hello again John.

My Kubota manual advises that, in the event of the motor continuing to run after the ignition has been switched off, a lever next to the injector pump ( it has a red painted machine screw in it and sits just above the cable operated engine speed control lever ) should be pushed towards the rear of the machine - which rotates it anti-clockwise against spring pressure which otherwise wants to turn it clockwise hard up against a stop.

With the ignition off or with the engine running, the actuating rod which protrudes out of the fuel shut off solenoid is fully extended by virtue of its engagement with the above-mentioned lever which is fully rotated clockwise against its stop. The act of switching the ignition off energises the solenoid which retracts the actuating rod and rotates the lever anti-clockwise against spring pressure to shut off fuel supply. After about 10 seconds, the solenoid relaxes and spring pressure returns the actuation rod to its normal extended position and with the lever back up against its stop.

David came round earlier and we had another play with the engine and this included removing the injectors again before reconnecting them externally to test the spray pattern. We got spray out of all three but David wasn't convinced that it was a fine enough mist. With jump leads to another battery to give the starter a bit more oooomph and the injectors re-fitted we got the engine to turn over a bit quicker and it coughed and farted and produced quite a bit of black smoke in the exhaust but wouldn't start which leads me to suspect that the fuel isn't atomising properly so the fuel / air mixture isn't explosive enough to produce a proper flame front. I have now taken the injectors to a local specialist to be tested and cleaned.

Curiously, when I disconnected the metal fuel pipes from the injectors and the injector pump, hardly any fuel came out of them whereas I would have expected them to be full of fuel.

I also rang a local garden machinery repair shop who have some experience of the D722 engine and the guy commented that this kind of starting problem is becoming something of a problem with diesel engines that are being run on red but haven't been started for some months and where the fuel hasn't been treated with a special additive. The changes to red diesel over the past couple of years ( apparently, mainly down the addition of biodiesel which is hygroscopic and encourages bacterial growth in the fuel ) is leading to fuel filters clogging up and I suspect that this has also caused problems with all 3 injectors. In any event, I should have some news on the state of my injectors over the next couple of days.

Out of interest John, whereabouts in the UK are you and what do you do to earn a crust?

Richard