Fuel injection timing

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Tazza

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Does anyone know how to set injection timing? I want to check it on a kubota engine that uses shims under the pump. The crank has ”FI” marks for fuel injection BUT does this indicate when the fuel should start to flow or should it be the end of the injection squirt. My manual says to use the inside of a pen so you can see the fuel move but it didn't say that it should start when the pointer hits the FI mark or it should have finished. I'm wondering if this is why an engine i have smokes a bit at startup, by a bit i mean a cloud if i didn't give it a really good glow. It may be squirting too early when the air isn't hot enough for ignition, and yes the compression is quite good, 375-400 PSI i think it was.
 

OldMachinist

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I've never done this procedure but this is what my manual says about it. This is for a Kubota D722. Hope it helps.

Timing The Injection Pump
Timing the fuel injection pump is done by changing the number of shims between the injection pump and engine block. Each shim will change the timing 1.5 degrees. The timing of the pump will be later when a shim is added, and earlier when a shim is removed.
To time the injection pump, use the following procedure:
Remove the number 1 cylinder high pressure tubeline from the injection pump.
Install a short pipe to the number 1 outlet of the pump. Point the pipe up (vertical).

With supply to the injection pump rotate the engine in a clockwise direction. Fuel must flow from the pipe as the timing mark on the flywheel pulley and the timing point are in alignment.
The correct timing for the engine is 20 to 22 degrees
B.T.D.C.
Add or subtract shims as needed to adjust the delivery time of the fuel injection pump. Each shim will change the timing 1.5 degrees..
 

Tazza

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I've never done this procedure but this is what my manual says about it. This is for a Kubota D722. Hope it helps.

Timing The Injection Pump
Timing the fuel injection pump is done by changing the number of shims between the injection pump and engine block. Each shim will change the timing 1.5 degrees. The timing of the pump will be later when a shim is added, and earlier when a shim is removed.
To time the injection pump, use the following procedure:
Remove the number 1 cylinder high pressure tubeline from the injection pump.
Install a short pipe to the number 1 outlet of the pump. Point the pipe up (vertical).
With supply to the injection pump rotate the engine in a clockwise direction. Fuel must flow from the pipe as the timing mark on the flywheel pulley and the timing point are in alignment.
The correct timing for the engine is 20 to 22 degrees B.T.D.C.
Add or subtract shims as needed to adjust the delivery time of the fuel injection pump. Each shim will change the timing 1.5 degrees..
Thats what my manual says too, so i assume fuel should start flowing at the FI mark.
 

Tazza

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Thats what my manual says too, so i assume fuel should start flowing at the FI mark.
Ok, i spoke to buddy that owns a diesel injection shop that does all my injection work. He told me how to check the timing as per a repair manual from Kubota. Its a little bit of fiddling, but it will tell me if the timing is correct or not. A job for when i get a chance! i'm pretty sure its out, we will see!
The FI mark is actually the end of the injection stroke (well it is for this engine).
 

dkveuro

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Ok, i spoke to buddy that owns a diesel injection shop that does all my injection work. He told me how to check the timing as per a repair manual from Kubota. Its a little bit of fiddling, but it will tell me if the timing is correct or not. A job for when i get a chance! i'm pretty sure its out, we will see!
The FI mark is actually the end of the injection stroke (well it is for this engine).
Tazza, to understand the injection timing point, is simply that the delivery plunger closes off the fuel injection barrel in the pump at the 22btdc mark and then starts to pressurize the fuel in the rack element barrel to begin injection............................................ If the i/p is an inline type, the following applies : To check injection timing, the line to #1 injector is removed and also the check element in the #1 pump delivery line holder. ( Use magnet, and observe how element check valve and spring assemble.) Place the throttle at WOT......................................... With some pressure in the i/p delivery system by the lift pump or other means, the fuel should stop welling up the #1 delivery hole just as the engine gets to 22btdc ( Your timing point.) on compression stroke. This is the point where the fuel is now trapped by the rack element plunger and no futher fuel can be pushed through and being as liquid is nearly incompressable, the injection sequence commences............................................ Black smoke = Over fueled.............................................. White smoke = Unburnt fuel, late i/p timing, engine cold, smoke should be minimal if all settings correct....................................................... This timing reference takes into concideration the ignition delay, actual start of combustion is most likely about 16 degrees or so btdc. FYFI... You can get a sensor that clamps to the delivery line and adaptor so you can set timing with a timing light.....of course you need to set timing on the type of engine first by the book, so you would know what the timing light would show............................. The other type is a Luminecent sensor that screws into the glow plug hole and does the same thing with the timing light...................................... This applies to all inline injection pumps, apart from the new generation of PD or electronic type. .
 

Tazza

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Tazza, to understand the injection timing point, is simply that the delivery plunger closes off the fuel injection barrel in the pump at the 22btdc mark and then starts to pressurize the fuel in the rack element barrel to begin injection............................................ If the i/p is an inline type, the following applies : To check injection timing, the line to #1 injector is removed and also the check element in the #1 pump delivery line holder. ( Use magnet, and observe how element check valve and spring assemble.) Place the throttle at WOT......................................... With some pressure in the i/p delivery system by the lift pump or other means, the fuel should stop welling up the #1 delivery hole just as the engine gets to 22btdc ( Your timing point.) on compression stroke. This is the point where the fuel is now trapped by the rack element plunger and no futher fuel can be pushed through and being as liquid is nearly incompressable, the injection sequence commences............................................ Black smoke = Over fueled.............................................. White smoke = Unburnt fuel, late i/p timing, engine cold, smoke should be minimal if all settings correct....................................................... This timing reference takes into concideration the ignition delay, actual start of combustion is most likely about 16 degrees or so btdc. FYFI... You can get a sensor that clamps to the delivery line and adaptor so you can set timing with a timing light.....of course you need to set timing on the type of engine first by the book, so you would know what the timing light would show............................. The other type is a Luminecent sensor that screws into the glow plug hole and does the same thing with the timing light...................................... This applies to all inline injection pumps, apart from the new generation of PD or electronic type. .
That is exactly what i was told, remove the valve and spring from number 1 carefully as to not remove the body that engages into the rack. Use the primer bulb and turn the crank till no more fuel will flow, at this point it is at FI . Its just a job i don't recommend anyone do unless they have removed the pump as its all factory set. If you accidentally remove the injector body from the rack you can mess up the fuel flow on that cylinder.
Its a shame i don't have one of those clamp on testers that you simply attach to a tube line, i have heard about them but they are very very costly.
Thanks for that info!!! hopefully i'll get to attack it on the weekend.
 

charger

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That is exactly what i was told, remove the valve and spring from number 1 carefully as to not remove the body that engages into the rack. Use the primer bulb and turn the crank till no more fuel will flow, at this point it is at FI . Its just a job i don't recommend anyone do unless they have removed the pump as its all factory set. If you accidentally remove the injector body from the rack you can mess up the fuel flow on that cylinder.
Its a shame i don't have one of those clamp on testers that you simply attach to a tube line, i have heard about them but they are very very costly.
Thanks for that info!!! hopefully i'll get to attack it on the weekend.
what colour of smoke does your engine produce at start up?,is it when cold only? it could be timing but it would be doing this from brand new, the procedure for timing these engines is called``spill timing``
 

Tazza

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what colour of smoke does your engine produce at start up?,is it when cold only? it could be timing but it would be doing this from brand new, the procedure for timing these engines is called``spill timing``
It blows a cloud of white smoke only at startup, its an engine i fully re-conditioned. But i had 2 pumps and sets of shims, i'm thinking i may have mixed the shims up and left 1 or 2 out. As one pump was dead the other i got re-conditioned, as with the injectors.
When warm it starts ok, but some times takes a glow to fire even when warm. Compression is about 375-400 PSI which i think is a touch low. I'm not sure if they set the piston to head height correctly.
I am going to build another one, but i need to take .025” off the deck, i'm thinking this was not done on the other one that has lowered the compression a bit. Its using aftermarket pistons that seem to be slightly shorter than the genuine Kubota ones.
 

dkveuro

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It blows a cloud of white smoke only at startup, its an engine i fully re-conditioned. But i had 2 pumps and sets of shims, i'm thinking i may have mixed the shims up and left 1 or 2 out. As one pump was dead the other i got re-conditioned, as with the injectors.
When warm it starts ok, but some times takes a glow to fire even when warm. Compression is about 375-400 PSI which i think is a touch low. I'm not sure if they set the piston to head height correctly.
I am going to build another one, but i need to take .025” off the deck, i'm thinking this was not done on the other one that has lowered the compression a bit. Its using aftermarket pistons that seem to be slightly shorter than the genuine Kubota ones.
Tazza...Even with 300 psi you should get a quick start after the glows have burnt for 20 second. The FI position? Do you know what the angle is? IE: ? BTDC ............................................. The inline pump should be 24 btdc with the spill timing method.....should also give a sharp crackle to the engine when opened up.......................................... If it needs glows after warmed, it is lazy timing....unless those piston rings leak............................. Have rebuilt many diesels and even down to 15 to 1 they start if the pistons/rings are tight. I use a 2nd oversize ring set on a standard bore to get reduced end gap...but more importantly radial pressure....this way, 1.6 ltr VW diesels will run 0.008thou end gaps and give 450 psi after bedding in.
 

Tazza

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Tazza...Even with 300 psi you should get a quick start after the glows have burnt for 20 second. The FI position? Do you know what the angle is? IE: ? BTDC ............................................. The inline pump should be 24 btdc with the spill timing method.....should also give a sharp crackle to the engine when opened up.......................................... If it needs glows after warmed, it is lazy timing....unless those piston rings leak............................. Have rebuilt many diesels and even down to 15 to 1 they start if the pistons/rings are tight. I use a 2nd oversize ring set on a standard bore to get reduced end gap...but more importantly radial pressure....this way, 1.6 ltr VW diesels will run 0.008thou end gaps and give 450 psi after bedding in.
Everything was bored out correctly as to their specs. The old liners were machined out and new liners were pressed in with a step so they can not drop like the old ones did. The piston to bore clerance was checked for each pot too. It was all good in that area as far as i remember. The only thing i didn't check was the piston to head height but i was told it was checked. Everything was taken back to standard size.
The engine i just did up had less than .008 end gap, i made sure i checked that, it works a treat!! just over 400 PSI of compression, it only takes a 10-15 second glow and it fires rite up, no smoke at all.
The only thing that could have caused the compression to be lower is when it was *new* i didn't get to give it a good run. It had short runs to move the machine around on flat ground, there was no load on it. I'm thinking the rings may have not seated correctly with the short work. It may have totalled maybee 30 mins of idle time over say 4 months in short bursts.
There is very little blow-by so i doubt its by-passing the rings.
I'm not sure what the setting on the FI mark on the balancer is, 24 degrees BTDC sounds about rite. I can check all this easily enough, i will need to work it out so i know how many shims are needed.
The crackle you mention when opening it up, you mean a good squirt of fuel? or when running?
 

skidsteer.ca

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Everything was bored out correctly as to their specs. The old liners were machined out and new liners were pressed in with a step so they can not drop like the old ones did. The piston to bore clerance was checked for each pot too. It was all good in that area as far as i remember. The only thing i didn't check was the piston to head height but i was told it was checked. Everything was taken back to standard size.
The engine i just did up had less than .008 end gap, i made sure i checked that, it works a treat!! just over 400 PSI of compression, it only takes a 10-15 second glow and it fires rite up, no smoke at all.
The only thing that could have caused the compression to be lower is when it was *new* i didn't get to give it a good run. It had short runs to move the machine around on flat ground, there was no load on it. I'm thinking the rings may have not seated correctly with the short work. It may have totalled maybee 30 mins of idle time over say 4 months in short bursts.
There is very little blow-by so i doubt its by-passing the rings.
I'm not sure what the setting on the FI mark on the balancer is, 24 degrees BTDC sounds about rite. I can check all this easily enough, i will need to work it out so i know how many shims are needed.
The crackle you mention when opening it up, you mean a good squirt of fuel? or when running?
Tazza
If the blow by is minimal then the rings must have seated correctly despite the short runs. We did a 6v53 detroit one winter and had to start it numerous time b4 we could put it to work. It took about 80 hours for it to seat up good, we were begining to worry, but it came around.
400 psi sounds like good compression.
Ken
 

Tazza

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Tazza
If the blow by is minimal then the rings must have seated correctly despite the short runs. We did a 6v53 detroit one winter and had to start it numerous time b4 we could put it to work. It took about 80 hours for it to seat up good, we were begining to worry, but it came around.
400 psi sounds like good compression.
Ken
I have about 20-30 odd hours up on this one.
The thing that worried me about the compression is my repair manual says they should be around 550 PSI. But i guess as long as it runs its all good.
 

charger

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I have about 20-30 odd hours up on this one.
The thing that worried me about the compression is my repair manual says they should be around 550 PSI. But i guess as long as it runs its all good.
WHAT YOU CAN DO TO SEE IF YOU HAVE PROPER COMPRESSION CC IS REMOVE THE INJECTOR AND SLIDE IN A THICK STRAND OF RESIN CORE SOLDER (MAKE SURE YOUR VALVES NO NOT CONTACT THE SOLDER,TURN THE ENGINE UNTIL IT COMPRESSES THE SOLDER,PULL IT OUT AND MEASURE IT WITH A CALIPER,IN MOST KUBOTA MANUALLS IT GIVES YOU THIS FIGURE FOR HEAD GASKET SHIMMING.
 

Tazza

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WHAT YOU CAN DO TO SEE IF YOU HAVE PROPER COMPRESSION CC IS REMOVE THE INJECTOR AND SLIDE IN A THICK STRAND OF RESIN CORE SOLDER (MAKE SURE YOUR VALVES NO NOT CONTACT THE SOLDER,TURN THE ENGINE UNTIL IT COMPRESSES THE SOLDER,PULL IT OUT AND MEASURE IT WITH A CALIPER,IN MOST KUBOTA MANUALLS IT GIVES YOU THIS FIGURE FOR HEAD GASKET SHIMMING.
Yeah, that was an option but i don't want to do that and find out its wrong :) If it is not rite, there is nothing i can do about it now.....
 

Tazza

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Yeah, that was an option but i don't want to do that and find out its wrong :) If it is not rite, there is nothing i can do about it now.....
I got time to have a fiddle today after work.
I ended up downloading and printing out a printable protractor off the net. I had to extend the graduations a little but it worked a treat!
The injection is 3 degrees early.
I think adding the 2 needed shims will have to wait for the weekend so i can take my time and re-check the timing before adding 515 to the shims and bolting it down to stay. Last time i didn't put loctite on the shims and the rotten thing was always wet around the injection pump. The things you learn!!!
 

dkveuro

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I got time to have a fiddle today after work.
I ended up downloading and printing out a printable protractor off the net. I had to extend the graduations a little but it worked a treat!
The injection is 3 degrees early.
I think adding the 2 needed shims will have to wait for the weekend so i can take my time and re-check the timing before adding 515 to the shims and bolting it down to stay. Last time i didn't put loctite on the shims and the rotten thing was always wet around the injection pump. The things you learn!!!
Tazza...the 'crackle' noise is from the engine coming under load quickly from idle...should sound sharp. .. . . . . . . . . . . This indicates engine timing pretty close. . . . . . . . . . . . . . . . . . . You said 3 degrees early ? You sure not 3 degrees late.....spill timing setting or other ? With early timing, most diesels will over heat under load.....especially Mercedes 240/300d's. Also a bad injector pattern will make smoke cold.....on modern diesels the glow plugs run for up to 10 minutes to reduce smoke and noise....although the glows on the 1998 up VW TDI's dont come on at all unless ambient temp's around 40f. . . . . . . . . . . . . . . . . . . You will need half load running of about 15 to 20 hours to bed in rings with modern oils.....suggest you don't use break in oil like a non detergent 30wt, but also never run synthetic oils until 100 plus hours .
 

Tazza

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Tazza...the 'crackle' noise is from the engine coming under load quickly from idle...should sound sharp. .. . . . . . . . . . . This indicates engine timing pretty close. . . . . . . . . . . . . . . . . . . You said 3 degrees early ? You sure not 3 degrees late.....spill timing setting or other ? With early timing, most diesels will over heat under load.....especially Mercedes 240/300d's. Also a bad injector pattern will make smoke cold.....on modern diesels the glow plugs run for up to 10 minutes to reduce smoke and noise....although the glows on the 1998 up VW TDI's dont come on at all unless ambient temp's around 40f. . . . . . . . . . . . . . . . . . . You will need half load running of about 15 to 20 hours to bed in rings with modern oils.....suggest you don't use break in oil like a non detergent 30wt, but also never run synthetic oils until 100 plus hours .
I did spill timing as you said to do.
The fuel cuts off 3 degrees before the pointer points at the FI mark using the spill technique.
The engine has never had a heat problem, i have been watching the temp gauge. I have never really given this machine a really hard run with constant serious load. It has done some hard work, just not constant.
The injectors and pump were both done professionally. New nozzles in the injectors. All tested and set to factory settings.
 

Tazza

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I did spill timing as you said to do.
The fuel cuts off 3 degrees before the pointer points at the FI mark using the spill technique.
The engine has never had a heat problem, i have been watching the temp gauge. I have never really given this machine a really hard run with constant serious load. It has done some hard work, just not constant.
The injectors and pump were both done professionally. New nozzles in the injectors. All tested and set to factory settings.
I'll try and take a short video of it starting and running before i fiddle with the timing then one after. See if my camera wants to work for me.
 

Tazza

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I'll try and take a short video of it starting and running before i fiddle with the timing then one after. See if my camera wants to work for me.
Ok, so i spent about 2 1/2 hrs today removing bits and pieces to gain access to the pump. Took it out and added 2 shims and re-checked timing. Put loctite on the shims and re-installed it again.
Gave me a little scare when it was starting. It started then just died, started again and refused to idle... it had be quite worried but after it purged all the air it ran just fine. I did bleed the tube lines before tightening them at the injectors to remove as much air as possible.
I will know in the next few days if it has fixed the problem or not, i just need to add a diode between the starter and glow solenoids so the 2 machines i have are essentially the same. I will then know if this has helped or not.
Thanks for the info on all this guys
 
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