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crosser

cant get engine to run.. HELP !!

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When you say "full tank of fuel", do you mean you filled/checked it yesterday, or it was full 8 weeks ago?  Could someone have siphoned off most of the tank, leaving just the crud in the bottom?  (Agree this doesn't explain the Ezy-start issue)

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Have you got it started yet?

I think there is enough info on this thread to start half a dozen reluctant diesels!

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54 minutes ago, Mad Harold said:

Have you got it started yet?

I think there is enough info on this thread to start half a dozen reluctant diesels!

Except some contributions in my view are misleading.

 

All the injectors I have ever bled only produce drips or a very small spit from a loosened injector union and in no way what I would describe as a "slug".  At full throttle a typical diesel injects something like a pinhead worth of fuel on each injections and that is not a "slug".

 

Trouble is we do not know exactly what the OP is seeing.

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2 minutes ago, Tony Brooks said:

Except some contributions in my view are misleading.

 

All the injectors I have ever bled only produce drips or a very small spit from a loosened injector union and in no way what I would describe as a "slug".  At full throttle a typical diesel injects something like a pinhead worth of fuel on each injections and that is not a "slug".

 

Trouble is we do not know exactly what the OP is seeing.

Which is why I said spurt rather than drip Tony. A spit is a better description, thank you.

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13 minutes ago, Tony Brooks said:

At full throttle a typical diesel injects something like a pinhead worth of fuel on each injections and that is not a "slug".

 

As DMR posted, the volume of each slug is tiny. Dave estimates 10 cubic millimetres.

 

Easy to work out. A three cylinder engine engine turning at say 1,500 rpm is injecting 1,500 x 3 / 2 x 60 times an hour. 135,000 slugs of fuel per hour. 

 

Let's assume its running at full power and burning say 3 litres of fuel an hour. 3 litres is 100 x 100 x 100 cubic mm. One million cubic millimetres.

 

1,000,000 / 135,000 = 7.4 cubic mm per injection stroke. 

 

A diesel starting cold is probably injecting the maximum possible size of droplet so Dave's calculation of the size of the injected droplet appears broadly correct. 

 

 

 

 

 

 

Edited by Mike the Boilerman
Delete some stray words

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4 hours ago, Mike the Boilerman said:

 

As DMR posted, the volume of each slug is tiny. Dave estimates 10 cubic millimetres.

 

Easy to work out. A three cylinder engine engine turning at say 1,500 rpm is injecting 1,500 x 3 / 2 x 60 times an hour. 135,000 slugs of fuel per hour. 

 

Let's assume its running at full power and burning say 3 litres of fuel an hour. 3 litres is 100 x 100 x 100 cubic mm. One million cubic millimetres.

 

1,000,000 / 135,000 = 7.4 cubic mm per injection stroke. 

 

A diesel starting cold is probably injecting the maximum possible size of droplet so Dave's calculation of the size of the injected droplet appears broadly correct. 

 

 

 

 

 

 

As an engineer I think I rounded my calculations to one decimal place. I had worked with 1 litre per hour and 800rpm, its all a bit arbitrary with these "fag packet" calculations. You are likely correct that the pump will try to deliver pretty much its maximum fuel when cranking, probably even more as I believe most pumps have some sort of "excess fuel" mechanism for starting. I still think its quite hard to estimate 7 cubic millimetres when its spilt all over the engine.

 

If the pump is producing fuel then its hard to see why this engine won't start, or at least try to start. Any injector nozzle failure or stuck piston ring is unlikely to happen on all three cylinders.

 

.............Dave

 

 

................Dave

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wow..  thankyou everyone for your help and ideas....   hopefully i will get down to the boat tomorrow to have a better look at the fuel system .. would of looked today but her indoors needs to help with my wheelchair down to the boat...   the stop lever was fully closing ok but not sure how the internals of it works incase something went wrong inside it...  will post how it goes...

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Unlike a petrol engine a diesel engine employs what is called a Stratified Charge.
Note also that a diesel engine always works on a wide open throttle, power is controlled by the quantity of fuel injected at any instant.

At maximum output the air/fuel ratio will be about 20:1, at tickover it might be as little as 70:1. This is where this stratified charge business enters the fray, the highly compressed and thus very hot air is made, by engine design, to rotate at speed, the fuel is sprayed into the rotating mass in tiny droplets where it spontaneously burns.


At anything less than maximum output this means that only the oxygen required to burn the fuel injected gets used hence the variable air/fuel ratio. The remaining air simply gets heated by the burning fuel, expands and helps push the piston down the bore.

 

A word of warning here, if checking the action of an injector out of the engine be warned that you are dealing with pressures around 2,000 psi (13.8 MPa) and droplet sizes around 10 microns, so stay well clear, it'll go straight through skin, blood in the circulation is good, diesel not so much! .

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8 hours ago, Man 'o Kent said:

Unlike a petrol engine a diesel engine employs what is called a Stratified Charge.
Note also that a diesel engine always works on a wide open throttle, power is controlled by the quantity of fuel injected at any instant.

At maximum output the air/fuel ratio will be about 20:1, at tickover it might be as little as 70:1. This is where this stratified charge business enters the fray, the highly compressed and thus very hot air is made, by engine design, to rotate at speed, the fuel is sprayed into the rotating mass in tiny droplets where it spontaneously burns.


At anything less than maximum output this means that only the oxygen required to burn the fuel injected gets used hence the variable air/fuel ratio. The remaining air simply gets heated by the burning fuel, expands and helps push the piston down the bore.

 

A word of warning here, if checking the action of an injector out of the engine be warned that you are dealing with pressures around 2,000 psi (13.8 MPa) and droplet sizes around 10 microns, so stay well clear, it'll go straight through skin, blood in the circulation is good, diesel not so much! .

 

Agree with all but the words "always works". Some older boats may well use pneumatically governed injection pumps. The BMCs larger than 2.5 litres come instantly to mind but I am sure there are others. These diesel engines do have a throttle butterfly so do not tend to vary the air to fuel ratio. the injection pump rack is moved by the depression caused by the the throttle butterfly. Nowadays these engines must be rarer and probably more easily found in vintage tractors or trucks but they exist. If you ever come across one do not be tempted to disconnect or damage the thin pipe(s) running between the throttle area and the diaphragm chamber on the injection pump. If they leak air the engine is likely to run at full throttle. The vast majority of diesels and the OP's are exactly as the above piece states but to avoid misinformation I feel its best to give the caveat.

 

Edited to add: Actually early BMC2.2s had pneumatic pumps and I think I have seem them on smaller, early Perkins as well.

 

I await the outcome of this saga with great interest.

Edited by Tony Brooks

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9 hours ago, Man 'o Kent said:

 

A word of warning here, if checking the action of an injector out of the engine be warned that you are dealing with pressures around 2,000 psi (13.8 MPa) and droplet sizes around 10 microns, so stay well clear, it'll go straight through skin, blood in the circulation is good, diesel not so much! .

I have read this many times and worried about it disproportionately.  The high pressures and tiny droplets are created more by the injector nozzles themselves than by the injection pump, so this warning really only applies when testing injectors for spray pattern. With an injector pipe disconnected the fuel does little more than a fast dribble/gentle squirt. There is perhaps a tiny risk of having an injector pipe just a tiny bit loose and so creating enough flow resistance to give a very high power tiny jet of fuel.

 

..................Dave

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2 hours ago, dmr said:

I have read this many times and worried about it disproportionately.  The high pressures and tiny droplets are created more by the injector nozzles themselves than by the injection pump, so this warning really only applies when testing injectors for spray pattern. With an injector pipe disconnected the fuel does little more than a fast dribble/gentle squirt. There is perhaps a tiny risk of having an injector pipe just a tiny bit loose and so creating enough flow resistance to give a very high power tiny jet of fuel.

 

..................Dave

Agreed but I think someone did suggest taking an injector out, inverting it on the pipe and spinning the engine. That's the bit that one needs to be very wary of. I think that with a very slightly loose union the nut itself would shroud the leak so where the fuel appears should be an all but zero pressure.

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well i managed to get down to the boat and zilch...  glow plugs all good..  fuel all clean and no water ...  took pipe of injector and turned engine over and fuel drips out of the pipe in time with the engine so i gather thats ok...    turn engine over with no throttle and half and full and nothing, no white smoke or anything...  tried the cheapy easystart again and nothing...     stop start mech seems to be working fine...   

 

but i now think it could be head gasket as i thought i would check the oil and there was water in the dipstick hole..  not creamy oil.. oil is still black but with water aswell...  only thing i can think is water is going into the head chamber and then seeping past the rings then into the sump...  

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19 minutes ago, crosser said:

well i managed to get down to the boat and zilch...  glow plugs all good..  fuel all clean and no water ...  took pipe of injector and turned engine over and fuel drips out of the pipe in time with the engine so i gather thats ok...    turn engine over with no throttle and half and full and nothing, no white smoke or anything...  tried the cheapy easystart again and nothing...     stop start mech seems to be working fine...   

 

but i now think it could be head gasket as i thought i would check the oil and there was water in the dipstick hole..  not creamy oil.. oil is still black but with water aswell...  only thing i can think is water is going into the head chamber and then seeping past the rings then into the sump...  

There is something not right here. If the engine was running fine previously then head gaskets don't just fail like that, and it would have to be a major failure to remove the compression on all cylinders.

Did the engine make any bad/unusual noises the first time you tried to start it?  Is there any way that water could have got into the engine? Are you in a marina or some remote spot? Is it possible the boat has taken on a lot of water into the engine bay and somebody else has pumped it out?  Has somebody stolen your cylinder head and loosely put their knackered one on in its place (it has been known!!!!!)

 

...............Dave

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Water in the oil soon goes creamy coloured oil. Could it be a small amount of unburnt diesel which has ended up in the sump due to none start via rings? Think you need some assistance with locating fault if you feel it is outside your comfort zone and knowledge it could be something quite simple. If it was running ok before it was turned off cannot see it being anything that bad.

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You need to do a compression test, its easy to do a basic check, rotate the engine by hand using the front pulley if you can, otherwise with suitable spanner. It should turn quite easily for a little way then get really stiff as it comes up to compression, you might even feel a bit of "spring" as the air is compressed, keep trying to turn and it will go as the compression leaks away, a little later it goes all hard work again as the next cylinder comes up to compression. With a bit of skill you could even deduce if you have one very bad cylinder etc.

 

.................Dave

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Sorry to see you are having problems with your engine-alot ot good suggestions on here already so cant really add alot to that but hasnt your boat got a wet exhaust ? Its been a while but I seem to remember it (my memory is crap though).

So the water may well not be coming from the head gasket as you have been turning it over alot without exhaust pressure to blow it all out..Just thought I would add at least a bit of optimism for you ☺️

 

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Bit of a long shot, has any work been done on the engine recently?

Servicing, tappets adjusted, oil changed, fuel filters changed, etc.

 

Bod

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If I may offer my tuppence worth: A cracked block or failed core plug would fit the above description. We did have that cold snap a couple of weeks ago: did you have coolant or water in the system? Sorry to be alarmist but as everyone else has said...it has to run....unless there is no compression. If the core plug lets into the cooling jacket then under these circumstances there would be very little of a tell tail. Has the oil level risen noticeably?

Sorry other way round. Does the core plug let into the crank case?  Same result a significant raise in the oil level

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Continuing with that theme. You would be able to check for a cracked block etc. by opening the oil filler then cranking the engine. If you get loads of pressure coming at you through the filler hole then you are probably on the right track.  P. S. Hope I'm wrong!

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A head gasket ring blown between two cylinders will allow an engine to crank , all the valves ect move as usual but it will not start, the compression just passes from one cylinder to the next. It would be unlucky for all three cylinders to be involved but not impossible. Test for such faults or valve faults by placing flat fingers over the intake and feeling for suction when cranking. Do not use your palm or other body parts cover it unless you want a hard to explain love bite.

 

Edited by Narrowboat Nimrod

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ive found a few videos on utube of kubota fuel pumps and there squirting more fuel than mine is so im going back to the boat later to see whats going on...  hoping it is a fuel issue..  if its just the pump itself ive seen a video where they just use a 12v pump instead so might go that route as the pump is a pig to get to on the engine...   will update later when i get back..  feeling confident now...

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7 minutes ago, crosser said:

ive found a few videos on utube of kubota fuel pumps and there squirting more fuel than mine is so im going back to the boat later to see whats going on...  hoping it is a fuel issue..  if its just the pump itself ive seen a video where they just use a 12v pump instead so might go that route as the pump is a pig to get to on the engine...   will update later when i get back..  feeling confident now...

I cannot see how a 'fuel issue' would stop in firing when using Easy-Start.

 

Are you sure it was actually Easy-Start you tried ?

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12 minutes ago, crosser said:

ive found a few videos on utube of kubota fuel pumps and there squirting more fuel than mine is so im going back to the boat later to see whats going on...  hoping it is a fuel issue..  if its just the pump itself ive seen a video where they just use a 12v pump instead so might go that route as the pump is a pig to get to on the engine...   will update later when i get back..  feeling confident now...

 

 

Does it have two fuel pumps?

 

IE a LP one and a HP one?

 

 

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i used a cheapy easystart so might just be rubbish....  yes has a normal pump then then the high pressure injector pump...  

 

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From what I am reading it sounds like the engine is not turning over fast enough you have every thing you need to start it

is the starter lazzy ?  

Graham

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