Inboard engine bleeding advice

[hannahcamille]

I have a macwester 28 with a Yanmar 2gm20f engine. I’ve just done a service and everything was going so well until the last bit where I changed the fuel filters. I’ve watched lots of videos of people doing this specifically with this engine and I just can’t get the engine to start. Here’s what happened:
1) Primary and secondary fuel filters changed
2) Primed first using the fuel pump on the engine (which doesn’t really feel like anything is happening when using it)
3) Primed by turning the engine over (someone recommended doing this with the decompression levers turned upwards and the seacock off to avoid flooding the engine with water)
After first attempt, the engine started for a few seconds and the stalled. So I tried to bleed the engine again with the first method.
There are bleed points on both filters and at the injectors, all of which when opened seem to be pouring out fuel with no visible air bubbles.
Now the engine won’t fire up at all.
I know it’s the fuel because it was working fine before I did this part…
Has anyone got any ideas or experience in bleeding this type of engine?
I would be so grateful for any input!
Thanks

 

[sailoppopotamus]

Did you try starting the engine again after the first attempt, or did you immediately try to bleed it again? Apologies for asking the obvious, but did you bring the decompression levers back down after the second attempt to bleed? I've only changed the filters once on mine and didn't have to bleed the injectors, just the first and secondary filters.

 

[hannahcamille]

Did you try starting the engine again after the first attempt, or did you immediately try to bleed it again? Apologies for asking the obvious, but did you bring the decompression levers back down after the second attempt to bleed? I've only changed the filters once on mine and didn't have to bleed the injectors, just the first and secondary filters.

Hi there! Yes I tried to start the engine again after it cut out and since then it turns over but doesn’t fire up. And yes I did put the decompression levers back down after bleeding it that way before I tried to start the engine again

 

[KompetentKrew]

Now the engine won’t fire up at all.

What's the state of the starter battery now? Are you on shore power, keeping it charged between attempts? My shore charger only charges the starter battery at a very low rate (just 1A, I think), so I guess if it's a bit too weak to turn the engine over properly then it could take some time to change back up again.

 

[bignick]

Deleted because I re-read your post.

 

[Plum]

I have a macwester 28 with a Yanmar 2gm20f engine. I’ve just done a service and everything was going so well until the last bit where I changed the fuel filters. I’ve watched lots of videos of people doing this specifically with this engine and I just can’t get the engine to start. Here’s what happened:
1) Primary and secondary fuel filters changed
2) Primed first using the fuel pump on the engine (which doesn’t really feel like anything is happening when using it)
3) Primed by turning the engine over (someone recommended doing this with the decompression levers turned upwards and the seacock off to avoid flooding the engine with water)
After first attempt, the engine started for a few seconds and the stalled. So I tried to bleed the engine again with the first method.
There are bleed points on both filters and at the injectors, all of which when opened seem to be pouring out fuel with no visible air bubbles.
Now the engine won’t fire up at all.
I know it’s the fuel because it was working fine before I did this part…
Has anyone got any ideas or experience in bleeding this type of engine?
I would be so grateful for any input!
Thanks

Couple of comments. 1) if it feels like the primer lever on the lift pump is not doing anything it's probable that the operating lever is on top of the cam, so turn the engine over half a revolution and try pumping again. 2) Do NOT try to bleed from the primary filter as the lift pump is "sucking" fuel through this one so every time you open the bleed screw and operate the pump you are sucking in more air. 3) close all bleed points, ensure the lift pump is not on the top of the cam then operate the pump lots (I assume you have not left the fuel tank isolation valve closed), bleed only from the secondary filter, close it, then try starting again. 4) maybe you have not made a perfect seal at all the o-rings/seals when you changed the fuel filters? especially if one of them is the CAV type of filter housing.

Edit: as pointed out by VicS, I should have said "turn the engine over one full revolution"

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[VicS]

Couple of comments. 1) if it feels like the primer lever on the lift pump is not doing anything it's probable that the operating lever is on top of the cam, so turn the engine over half a revolution and try pumping again. 2) Do NOT try to bleed from the primary filter as the lift pump is "sucking" fuel through this one so every time you open the bleed screw and operate the pump you are sucking in more air. 3) close all bleed points, ensure the lift pump is not on the top of the cam then operate the pump lots (I assume you have not left the fuel tank isolation valve closed), bleed only from the secondary filter, close it, then try starting again. 4) maybe you have not made a perfect seal at all the o-rings/seals when you changed the fuel filters? especially if one of them is the CAV type of filter housing,

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If the lever is on the top of the cam turning the engine 1 full turn will turn the camshaft by half of a turn so that the lever is then on the heel of the cam

 

[penberth3]

If the lever is on the top of the cam turning the engine 1 full turn will turn the camshaft by half of a turn so that the lever is then on the heel of the cam

Yes, but in practice I've never worried about how much to turn, a quick flick of the starter usually does the trick.

 

[bignick]

The order you bleed is specific - you need to go from the tank to the injectors.
Mine was a bit reluctant to fire up following a change of primary fuel filter, so I’d recommend you have another go. It doesn’t take much air to cause the injectors not to open, so even a small air leak can prevent it working. I’d start by refitting the filters - if it worked before then it is most likely a change you have introduced.

keep going and be persistent, but if you need to keep spinning it then it’s worth shutting the inlet seacock to prevent back flooding through the exhaust elbow.

 

[Tranona]

A common source of air on the Yanmar is the seal on the fuel filter housing not seated properly.

 

[zulloboy]

Apologies if I missed it, but you might need to bleed where the line from the secondary filter enters the top of the injection pump.

 

[coopec]

The order you bleed is specific - you need to go from the tank to the injectors.
Mine was a bit reluctant to fire up following a change of primary fuel filter, so I’d recommend you have another go. It doesn’t take much air to cause the injectors not to open, so even a small air leak can prevent it working. I’d start by refitting the filters - if it worked before then it is most likely a change you have introduced.

keep going and be persistent, but if you need to keep spinning it then it’s worth shutting the inlet seacock to prevent back flooding through the exhaust elbow.

I wondered why no-one had mentioned that!

 

[fredrussell]

On my 3GM30 I was pumping away on the manual lift pump thinking I was pulling fuel through. I found out later I wasn’t pushing the lever far enough through its stroke. On mine it’s the last 10mm of its 50mm travel that pulls fuel through the pump - though I now wonder if my cam was in the wrong position as detailed above?

 

[IanCC]

The pump, as has been said, only pumps in the last part if its movement. The first part is just taking up the slack. So you should feel two distinct different pressures when operating the lever. First it feels like it is doing nothing, it isn't, then a firmer pressure.

If you didn't fill the primary filter with diesel it will take a lot of pumping through. Hundreds of pumps. As has been said, don't bleed at the primary but at the secondary. Bleed to injector pump. Then decompress and spin engine for a few seconds. Then it zhould start.

If you have flex hose from secondary filter to pump, you can remove from filter and watch for solid diesel shooting out when you pump.

It won't matter if you haven't got everything supertight it should start. An air leak would manifest itself by needing to bleed before starting on subsequent occasions.

Be careful not to try starting too much or you can back flood the engine by filling the exhaust system with water. Best to keep seacock closed until it starts. Then open immediately. Make sure pump is wet though. I pour a little water in the raw water strainer.

 

[Mister E]

It sounds like you have air in the injectors, I am not sure about bleed points at them. Could that be the leak off rail?
It is normal to have to slacken the high pressure pipes to the injectors to bleed them.
After bleeding the injectors I like to tighten on pipe with the engine being turned over until it starts.
Then tighten the other pipes properly (this is for older engines not electronic controled).

 

[Blueboatman]

All as above..

But , if you then fit an outboard motor type rubber primer fuel bulb in line between the boats fuel tank and the primary filter/water separator unit, you will find that bleeding in future becomes so much much easier and you can ignore the sodding fuel pump lever..

Now, You just open the one 10mm screw/bolt which sits at the top face of the injector pump casting, squeeze the primer bulb until bubble free fuel squires out, nip it tight and spin the motor over on wide open throttle , it will self bleed from there, no need to touch the injector pipes.

It will fire up within 10 or so seconds ..probably on one then both cylinders and settle down normally ..
How easy is that ?

NOTE: Of course you may wish to close the seawater inlet whilst messing around if you are continually spinning over the engine repeatedly.
Otherwise seawater is being introduced and not expelled , you do not want a back flood of sea water into the engine via an exhaust valve! -You prob know this already of course )

 

[snowbird30ds]

Rig an oil vacuum pump to the last bleed screw in the system with any others closed and suck it through till clear fuel in pipe, then bleed injectors with throttle full open, nip up injectors while still spinning over and be prepared to shut throttle quick when it fires up.
No experience of you particular engine but usually works a treat on most old school diesels, sometimes helps if you can shut off fuel return while you use vacuum in case it can suck back that way.
I've not bothered with lift pump levers for years now.

 

[bignick]

It’s worth watching this:

 

[hannahcamille]

Hi everyone, thanks so much for all responses. I’ve managed to get it working! A few things I did based on the above:
1) the primary filter is the CAV style one and I wasn’t sure if the seal was tight from when I first changed it, so I took it off and redid. I stupidly didn’t realise before there was an additional o ring that goes in the upper metal housing, so I replaced the one that was there. Not sure if that was causing a problem. But good to get it all changed and put my mind at rest that this bit was sorted. To bleed this it seemed to just be a case of opening the bleed screw and then opening the fuel line and it filled up and then bubbles until smooth diesel.
2) turned the engine over briefly to move the position of the cam and this seemed to make the fuel pump lever work, but you’re right it’s the last centimetre that does anything so persistence is key. Will definitely look into getting a bulb installed in the fuel line like someone said! Sounds much better and I’ve seen a video since about this.
3) bled from the secondary fuel filter until smooth diesel and no bubbles.
4) then bled from the injector bleed screw and there was a hiss of air and bubbles before smooth diesel.
5) then ran it for a few seconds with decompression levers up and sea cock closed
6) then out decompression levers down and it started straight away, immediately opened sea cock and it ran fine for a few minutes so it all seems back to normal!

Thanks so much everyone I’m a happy girl done my first engine service and it’s working (well until the next problem, as we all know with boats lol)
Cheers

 

[Plum]

Hi everyone, thanks so much for all responses. I’ve managed to get it working! A few things I did based on the above:
1) the primary filter is the CAV style one and I wasn’t sure if the seal was tight from when I first changed it, so I took it off and redid. I stupidly didn’t realise before there was an additional o ring that goes in the upper metal housing, so I replaced the one that was there. Not sure if that was causing a problem. But good to get it all changed and put my mind at rest that this bit was sorted. To bleed this it seemed to just be a case of opening the bleed screw and then opening the fuel line and it filled up and then bubbles until smooth diesel.
2) turned the engine over briefly to move the position of the cam and this seemed to make the fuel pump lever work, but you’re right it’s the last centimetre that does anything so persistence is key. Will definitely look into getting a bulb installed in the fuel line like someone said! Sounds much better and I’ve seen a video since about this.
3) bled from the secondary fuel filter until smooth diesel and no bubbles.
4) then bled from the injector bleed screw and there was a hiss of air and bubbles before smooth diesel.
5) then ran it for a few seconds with decompression levers up and sea cock closed
6) then out decompression levers down and it started straight away, immediately opened sea cock and it ran fine for a few minutes so it all seems back to normal!

Thanks so much everyone I’m a happy girl done my first engine service and it’s working (well until the next problem, as we all know with boats lol)
Cheers

Glad it's running . Thanks for the feedback

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