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Old 02-03-2016, 01:06   #16
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Re: How to Bleed my Yanmar GM30 fuel line

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Originally Posted by four winds View Post
G2l,
I believe the return spring on your lever is not functioning. It should rise to the top of its travel when released.

Indeed the pumping part of the stroke is near the bottom of the total movement of the lever. About a quarter inch or so to my eye.
Rotate the crankshaft a little bit to move the fuel pump crank off the top of the lobe on the camshaft and the lever action on the pump will pump more fuel.
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Old 02-03-2016, 05:09   #17
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Re: How to Bleed my Yanmar GM30 fuel line

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Originally Posted by four winds View Post
G2l,
I believe the return spring on your lever is not functioning. It should rise to the top of its travel when released.

Indeed the pumping part of the stroke is near the bottom of the total movement of the lever. About a quarter inch or so to my eye.
Thank you,

Appreciate your insights. I think that we are onto something here.

G2L
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Old 02-03-2016, 05:52   #18
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OK, Understood, but ...

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Originally Posted by Badsanta View Post
Did you replace the filters? Wont start? The fuel pump only moves fuel to the high pressure injector pump. Once fuel is bled to the injector pump you MUST crank the engine to get fuel through the injector pump and then bled at each injector. This CANNOT be done without cranking the engine. Did you replace the banjo washers at the lift pump? Common problem lots of info here.
To clarify: I replaced the old electric fuel pump and added an inline fuel filter situated before the new electric pump. Both of these are only about a month old and precede the mechanical pump attached to the engine and the fuel filter that follows it. The new, inline filter, has a hand pump that is used to bleed air from the line, but, obviously, this will not eliminate air trapped further down the fuel line.

From my understanding of your post above, you think that just bleeding the line at the mechanical fuel pump will not suffice to clear the fuel line, and that air could be trapped in the injectors, themselves. Correct?

If so, if air in the line is actually the problem, I wonder why it seems to have taken so long for the air to reach mechanical fuel pump and/or the injectors. That may sound like a dumb question, but we replaced the items noted above and used the new inline filter to pump out any air that it might help get rid of. The diesel ran fine for a number of days and for, perhaps, 12 hours in total.

A few weeks later, we were able to start the engine, but it conked out after about 15 minutes. There is fuel in the tank, and it looks clear, (no milky fuel). Also, the fuel line, which is see-through chem hose, looks clear (no milky fuel or air bubbles). But we have not been able to start the engine after the moment it died.

Seems to me, that if there is air in the line, it must have got in when we were replacing the old fuel pump and adding the in-line filter. But, that was weeks ago, and the engine ran well until just a few days ago. If air got into the later, how did that happen? Not sure what to make out of any of this; so any input from you more experienced folks would certainly help.

Thanks for your comments.

G2L
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Old 02-03-2016, 06:38   #19
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pirate Re: How to Bleed my Yanmar GM30 fuel line

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Originally Posted by Badsanta View Post
Yeah that wont work. Lol
Seeing as I've been doing it for 30yrs.. I guess it must be down to you screwing up somewhere down the line..
Or your a 'Call the engineer' type...


PS: Another 'Won't Work' thing I do is fit car type in line filters at 1euro each.. extends the life of my expensive separator filters greatly and can be changed in less than a minute..
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Old 02-03-2016, 07:17   #20
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pirate Re: OK, Understood, but ...

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Originally Posted by Gone2long View Post

Seems to me, that if there is air in the line, it must have got in when we were replacing the old fuel pump and adding the in-line filter. But, that was weeks ago, and the engine ran well until just a few days ago. If air got into the later, how did that happen? Not sure what to make out of any of this; so any input from you more experienced folks would certainly help.

Thanks for your comments.

G2L
Have you cleaned out your tank recently.?
A boat I was delivering ran low on fuel by the time I reached Nuku Hiva.. so knowing that US Samoa has the cheapest fuel in the S Pacific I just got enough to keep the generator going and serve the engines for the 1500 odd miles getting there.. however after filling the tank I then started getting the same problem.. which is basically fuel starvation.. changed/checked everything.. no joy.. run a while then cough and die..
So as I had time to kill while waiting for the owner to fly out and 'Crew'.. I broke into the pipe linking the 2 tanks P - S and fed direct from there to the pump and on to the engine and generator.. never had another problem..
Conclusion.. crap had been sucked into the pick-up tube and was partially blocking it.. fine for tick over but the minute load came on the feed could not keep up and the engine would die..
Man that boat was a succession of disasters spread over 5-6mths.. including an engine room fire..
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Old 02-03-2016, 07:39   #21
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Hmmm ... Sounds familiar ...

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Originally Posted by boatman61 View Post
Have you cleaned out your tank recently.?
A boat I was delivering ran low on fuel by the time I reached Nuku Hiva.. so knowing that US Samoa has the cheapest fuel in the S Pacific I just got enough to keep the generator going and serve the engines for the 1500 odd miles getting there.. however after filling the tank I then started getting the same problem.. which is basically fuel starvation.. changed/checked everything.. no joy.. run a while then cough and die..
So as I had time to kill while waiting for the owner to fly out and 'Crew'.. I broke into the pipe linking the 2 tanks P - S and fed direct from there to the pump and on to the engine and generator.. never had another problem..
Conclusion.. crap had been sucked into the pick-up tube and was partially blocking it.. fine for tick over but the minute load came on the feed could not keep up and the engine would die..
Man that boat was a succession of disasters spread over 5-6mths.. including an engine room fire..
Hah, you been readin' my mail (Kris Kristofferson). My newly purchased boat has kept me duly busy for the last year, since all of my past experience has been as crew, never having to suffer the pangs of actually owning a boat.


Consequently, I am relying on the manual, and advice from experienced hands like you. The manual keeps talking about various forms of fuel delivery/blockage problems as the cause of my issues. Correlates closely what you and others have suggested.

Have not cleaned the tank and that will be pretty hard to do for a number of reasons. However, I will consider some type of obstruction to the fuel supply as the most likely culprit, and investigate further.

Thanks, for your help,


G2L
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Old 02-03-2016, 07:43   #22
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Re: How to Bleed my Yanmar GM30 fuel line

We might be chasing wild geese, here. It seems that this installation uses an electric fuel pump, so trying to bleed the system using the mechanical feed pump won't help. This system uses a low-pressure pump to feed fuel to the high-pressure side. The low-pressure side fills up the injection pump so the high-pressure side has a supply of fuel. This is the low-pressure side of the system that you bleed using the bleed valves. At the injector-pump end of each high-pressure line leading to the injector is a fuel delivery valve. See #3




A cutaway view here



The discharge valve opens when a high-pressure shot is pushed past it as the plunger travels upward. The discharge valve closes after the shot of fuel kicks the injector open at each cylinder. A small amount of fuel is kept under some pressure in the pipe and injector after the injector nozzle comes back down to it's seat.



If the discharge valve isn't opening and closing as it is designed the injector plunger can't keep up at low engine speeds. The injector pipe must be refilled by the injector pump after every firing event. There is supposed to be a small amount of fuel trapped in the injector pipe between firing events.

Many times the symptom is 'hard to start' or 'runs rough at low speeds'.

When servicing the discharge valve, unscrew the nuts on both ends of the high-pressure pipes. Be careful with them because they can be brittle. So not bend them out of the way.

You can take the discharge valve apart and use WD40 to clean it without messing up any of the adjustments, but when you put it all together again you will have air in the pipes. Then, you guessed it, you have to bleed the air from the high-pressure side. Use the compression releases to let the engine spin over freely. While cranking the engine, one at a time, loosen the nut at the injector to allow air and air-mixed fuel to escape. Do not crank the engine for more than 15 or 20 seconds at a try. After all three injector pipes are free of air, engage the decompression valves and start the engine.

I see this happen with more often with modern fuel formulations, especially after the engine is unused for a few months. Even a microscopic piece of debris will keep the discharge valve from working correctly.
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Old 02-03-2016, 07:56   #23
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Thanks - Re: How to Bleed my Yanmar GM30 fuel line

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Originally Posted by guyfromiowa View Post
We might be chasing wild geese, here. It seems that this installation uses an electric fuel pump, so trying to bleed the system using the mechanical feed pump won't help. This system uses a low-pressure pump to feed fuel to the high-pressure side. The low-pressure side fills up the injection pump so the high-pressure side has a supply of fuel. This is the low-pressure side of the system that you bleed using the bleed valves. At the injector-pump end of each high-pressure line leading to the injector is a fuel delivery valve. See #3




A cutaway view here



The discharge valve opens when a high-pressure shot is pushed past it as the plunger travels upward. The discharge valve closes after the shot of fuel kicks the injector open at each cylinder. A small amount of fuel is kept under some pressure in the pipe and injector after the injector nozzle comes back down to it's seat.



If the discharge valve isn't opening and closing as it is designed the injector plunger can't keep up at low engine speeds. The injector pipe must be refilled by the injector pump after every firing event. There is supposed to be a small amount of fuel trapped in the injector pipe between firing events.

Many times the symptom is 'hard to start' or 'runs rough at low speeds'.

When servicing the discharge valve, unscrew the nuts on both ends of the high-pressure pipes. Be careful with them because they can be brittle. So not bend them out of the way.

You can take the discharge valve apart and use WD40 to clean it without messing up any of the adjustments, but when you put it all together again you will have air in the pipes. Then, you guessed it, you have to bleed the air from the high-pressure side. Use the compression releases to let the engine spin over freely. While cranking the engine, one at a time, loosen the nut at the injector to allow air and air-mixed fuel to escape. Do not crank the engine for more than 15 or 20 seconds at a try. After all three injector pipes are free of air, engage the decompression valves and start the engine.

I see this happen with more often with modern fuel formulations, especially after the engine is unused for a few months. Even a microscopic piece of debris will keep the discharge valve from working correctly.
A daunting task for a diesel amateur like me, but, I might be able to get a friend to assist, and we will start from the easiest to the hardest to accomplish task, the one you note above being a bit down the line right now.

Thanks for the detailed and potentially invaluable post.

Sincerely appreciate your input.

G2L
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Old 02-03-2016, 08:11   #24
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Re: How to Bleed my Yanmar GM30 fuel line

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Rotate the crankshaft a little bit to move the fuel pump crank off the top of the lobe on the camshaft and the lever action on the pump will pump more fuel.
Yes of course this is correct. But not the reason I posted the comment.

There is always some free play in the priming lever regardless of lobe position. Apparently to lift it clear during normal operation.

My comment was to show a possible indication of the general condition of the lift pump. And not to suggest this symptom was the sole source of the OP's issue. Should have made that clear earlier.
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Old 02-03-2016, 08:18   #25
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Re: How to Bleed my Yanmar GM30 fuel line

With all the installing filters and pumps it would be very easy to bump and loosen a fuel line connection and let air get sucked in. If any air gets to the injector the air keeps getting compressed and keeps the injector from poping open. With the problems I have had with my yanmar 3gm30f I would do the following.
Make sure the battery is fully charged as you need a quick solid fast crank to get the pressure to create the heat to start combustion.
Check to make sure the stop lever is fully pushed in. I had mine left part way out after a shut down and wasted hours till I pushed it back a half inch.
After doing the above I would bleed the fuel lines from the tank all the way to the injectors. I have found it impossible to force fuel through the high pressure injecton pump with out cranking the motor. I know some motors are diffrent.
Also remember that excessive cranking keeps pumping raw water and will fill your exaust system up with water and back up into your engine causing hydraulic locked. If that happens turn your through hull seacock off drain your exaust open the de compression levers to let the water out. Start motor change oil and restart and let run. Check oil color again. You may have to change the oil several times to clear the water out.
I have had to do all the above several times before and this works for my 3gm30f. Imho
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Old 02-03-2016, 09:51   #26
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Thanks - Re: How to Bleed my Yanmar GM30 fuel line

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Originally Posted by Badsanta View Post
With all the installing filters and pumps it would be very easy to bump and loosen a fuel line connection and let air get sucked in. If any air gets to the injector the air keeps getting compressed and keeps the injector from poping open. With the problems I have had with my yanmar 3gm30f I would do the following.
Make sure the battery is fully charged as you need a quick solid fast crank to get the pressure to create the heat to start combustion.
Check to make sure the stop lever is fully pushed in. I had mine left part way out after a shut down and wasted hours till I pushed it back a half inch.
After doing the above I would bleed the fuel lines from the tank all the way to the injectors. I have found it impossible to force fuel through the high pressure injecton pump with out cranking the motor. I know some motors are diffrent.
Also remember that excessive cranking keeps pumping raw water and will fill your exaust system up with water and back up into your engine causing hydraulic locked. If that happens turn your through hull seacock off drain your exaust open the de compression levers to let the water out. Start motor change oil and restart and let run. Check oil color again. You may have to change the oil several times to clear the water out.
I have had to do all the above several times before and this works for my 3gm30f. Imho
Thanks,

More stuff to ponder/check out. I'm starting to get overwhelmed, and it's 1am where I am, so I'll check out for the time being, try to sort some troubleshooting priorities, and proceed from there.

Appreciate all the great experience and advice,

G2L
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Old 02-03-2016, 09:55   #27
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Re: How to Bleed my Yanmar GM30 fuel line

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Or.. you could be lazy like me and perma fit a rubber bulb pump into your line at a handy spot then crack open the furthest injector and start squeezing..
Those levers are terrible. Do this^^^^^ or get an elelctric fuel pump for this purpose. Also, I've always found that just bleeding at the injectors will work fine, but then I never had a big problem either.... Usually the engine will start in a few seconds of bleeding by cranking the engine.
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Old 02-03-2016, 10:26   #28
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Re: How to Bleed my Yanmar GM30 fuel line

Actually, that's more or less how I bleed mine. Squeeze bulb to Racor filter to engine, open each injector in turn. That little lever takes forever to do it.
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Old 02-03-2016, 13:21   #29
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Re: How to Bleed my Yanmar GM30 fuel line

The bleed screw on the engine filter is the inboard one. Of course that's the one you can't get at easily. The lever action priming pump seems to only be pumping on the very bottom of the lever stroke. Seems like it can't be moving much fuel at all and even thought it was broken the first time I primed the engine. On my boat it seems to create a syphon from the tank and after a bit of cycling of the lever fuel flows to the bleed screw without pumping. Don't know if that would be the case on anyone elses boat.
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Old 02-03-2016, 15:35   #30
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Re: How to Bleed my Yanmar GM30 fuel line

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The bleed screw on the engine filter is the inboard one. Of course that's the one you can't get at easily. The lever action priming pump seems to only be pumping on the very bottom of the lever stroke. Seems like it can't be moving much fuel at all and even thought it was broken the first time I primed the engine. On my boat it seems to create a syphon from the tank and after a bit of cycling of the lever fuel flows to the bleed screw without pumping. Don't know if that would be the case on anyone elses boat.
FWIW, I measured the volume pumped by the stock fuel pump on the 2GM20. On the bench it moved about 3cc per full stroke. This is many times more than the engines uses but I am pretty sure the pump does not complete a full stroke when fitted to the engine. It looks like the cam lobe only moves the pump maybe a half or less of the full stroke distance.

I endorse the use of a flexible blub pump as suggested by Boatie and others; certainly makes the job 10 times easier
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