Bmc 1.8 bleed issue

[Sam T]

Hi,

 

I've changed my fuel filter on a bmc 1.8 this morning, which I 've done before no problem at all.

 

Today I undid one of the screws on the filter top and started pumping the lift pump for about 20 pumps before realising I hadn't opened the cocks on the fuel lines again. Guess this was a mistake but not sure of the consequences or how to resolve. 

 

Having reopened the fuel lines I cannot get anything to come out using the lift pump. Have opened screw on the filter top and nothing happening (have rechecked by taking the filter off again and there is no fuel in there) so think I must have created an airlock before the fuel filter.

 

I've tried opening the screw on the fuel pump for the pipe that goes to the filter, but not getting anything out of there using the lift pump either.

 

Would anyone have any suggestions as to what my next step should be/where else I can bleed it from to sort this out?

 

I haven't cranked the engine at all yet as i

Know I won't always need to bleed the high pressure side just from changing the fuel filter if I don't.

 

I only got to my current spot yesterday, so have 2 weeks to sort it out before I need to move. Grateful for any tips though!

 

Thanks in advance.

[Tony Brooks]

40 minutes ago, Sam T said:

Hi,

 

I've changed my fuel filter on a bmc 1.8 this morning, which I 've done before no problem at all.

 

Today I undid one of the screws on the filter top and started pumping the lift pump for about 20 pumps before realising I hadn't opened the cocks on the fuel lines again. Guess this was a mistake but not sure of the consequences or how to resolve. 

 

Having reopened the fuel lines I cannot get anything to come out using the lift pump. Have opened screw on the filter top and nothing happening (have rechecked by taking the filter off again and there is no fuel in there) so think I must have created an airlock before the fuel filter.

 

I've tried opening the screw on the fuel pump for the pipe that goes to the filter, but not getting anything out of there using the lift pump either.

 

Would anyone have any suggestions as to what my next step should be/where else I can bleed it from to sort this out?

 

I haven't cranked the engine at all yet as i

Know I won't always need to bleed the high pressure side just from changing the fuel filter if I don't.

 

I only got to my current spot yesterday, so have 2 weeks to sort it out before I need to move. Grateful for any tips though!

 

Thanks in advance.

Try it with the filler cap off just in case the tank breather is blocked.

 

If the engine stopped in an odd position you may only have only a fraction of the lift pump's stroke. This will show by a lot of slack and little resistance on the priming lever at first. Try turning the engine over one full turn to get the eccentric away from the pump lever.

 

Does your installation have any form of filter or water separator between the tank and lift pump. If so make sure that is clean.

 

Then make sure the gauze strainer in the top of most BMC lift pumps is clean, ditto the sediment trap below it.

 

Then try blowing back into the tank. It may be the fuel cock is still off. You may have two, one for the return pipe.

 

Once you are sure the cock is open and if you can't blow back into the tank it means you have a blockage in the pipe or a mat of bug floating around in the tank.

 

 

[Tony Brooks]

If the pump is ejecting air form the bleed point the you may have ruin out of fuel, got an air leak into a pipe union or the fuel tap, or the pickup pipe in the tank has split.

[Sam T]

Thanks for the suggestions. I have tried will the fill cap off and that made no difference.

 

I definitely have plenty of fuel, can see it to quite a high level in the tank.

 

There is no filter between the tank and the fuel pump so nothing to clean there.

 

The lift pump feels as it always did, it's definitely not lacking it's usual resistance. I haven't cranked the engine yet. Won't this suck air into the injector pump and mean I'll have more bleeding to do later on than is necessary? Obv if I need to then I need to, but from what you're saying the lift pump doesn't indicate that this is the problem.

 

There are 2 fuel cocks and both are definitely now open.

 

I don't think the pump is ejecting air from the bleed points, or certainly not a noticeable amount, it appears to just be doing nothing.

 

In terms of cleaning the strainer and tray on the pump, would this be done by removing the top screw on the pump? I've read in other posts that bleeding through this one is most risky for a novice, and adjusting it incorrectly can lead to issues or something along those lines? I'm definitely not an expert in this stuff so only really want to try things if there's little/no risk involved, otherwise will call a mechanic.

 

When you say blowing back into the tank, is it possible to clarify what you mean by this? I.e. what would I actually be physically doing. A novice as I say!

 

Blockage in the pipes or diesel bug sound far more worrying. Is it naive to assume that because the engine was all working absolutely perfectly before I messed with the fuel filter that this is unlikely to be the case?

 

Would it be a stupid thing to do to loosen the nut where the fuel pipe from the tank joins the pump to check whether diesel is coming down that and definitely getting into the pump in the first place?

 

Thanks again, and apologies if I'm asking stupid questions.

[Boater Sam]

34 minutes ago, Sam T said:

Thanks for the suggestions. I have tried will the fill cap off and that made no difference.

 

I definitely have plenty of fuel, can see it to quite a high level in the tank.

 

There is no filter between the tank and the fuel pump so nothing to clean there.

 

The lift pump feels as it always did, it's definitely not lacking it's usual resistance. I haven't cranked the engine yet. Won't this suck air into the injector pump and mean I'll have more bleeding to do later on than is necessary? Obv if I need to then I need to, but from what you're saying the lift pump doesn't indicate that this is the problem.

 

There are 2 fuel cocks and both are definitely now open.

 

I don't think the pump is ejecting air from the bleed points, or certainly not a noticeable amount, it appears to just be doing nothing.

 

In terms of cleaning the strainer and tray on the pump, would this be done by removing the top screw on the pump? I've read in other posts that bleeding through this one is most risky for a novice, and adjusting it incorrectly can lead to issues or something along those lines? I'm definitely not an expert in this stuff so only really want to try things if there's little/no risk involved, otherwise will call a mechanic.

 

When you say blowing back into the tank, is it possible to clarify what you mean by this? I.e. what would I actually be physically doing. A novice as I say!

 

Blockage in the pipes or diesel bug sound far more worrying. Is it naive to assume that because the engine was all working absolutely perfectly before I messed with the fuel filter that this is unlikely to be the case?

 

Would it be a stupid thing to do to loosen the nut where the fuel pipe from the tank joins the pump to check whether diesel is coming down that and definitely getting into the pump in the first place?

 

Thanks again, and apologies if I'm asking stupid questions.

No, but it may be better to loosen the outlet side of the lift pump and see if it will prime. If not take the top off and check the strainer in there. Care needed not to cross any threads in the aluminum body.

Edited August 17, 2019 by Boater Sam

[Sam T]

I'd tried loosening the outlet side of the pump but no joy.

 

I have v carefully taken the top off as suggested which I've never done before. As far as I can see there doesn't appear to a strainer in there. Appreciate this probably isn't great but hoping I can  worry about this at a later date.

 

It was full of fuel up to the point where the top comes off, so there is fuel in there, just doesn't seem to be being pumped.

 

However with the fuel lines from the tank open, should I not have been expecting the pump to overflow with new fuel coming in with the top off? If the pipes weren't blocked that is?.....

[Tony Brooks]

1 minute ago, Sam T said:

I'd tried loosening the outlet side of the pump but no joy.

 

I have v carefully taken the top off as suggested which I've never done before. As far as I can see there doesn't appear to a strainer in there. Appreciate this probably isn't great but hoping I can  worry about this at a later date.

 

It was full of fuel up to the point where the top comes off, so there is fuel in there, just doesn't seem to be being pumped.

 

However with the fuel lines from the tank open, should I not have been expecting the pump to overflow with new fuel coming in with the top off? If the pipes weren't blocked that is?.....

1. Not all BMC pumps have strainers, I think the Indian ones did away with them and there is a different design of pump on some engines

 

2. Not if air got into the pipe when the filter was off. If you can try putting your mouth around the breather and blowing hard to see if you can force fuel from the lift pump with the top off it.

 

 

47 minutes ago, Sam T said:

Thanks for the suggestions. I have tried will the fill cap off and that made no difference.

 

I definitely have plenty of fuel, can see it to quite a high level in the tank.

 

There is no filter between the tank and the fuel pump so nothing to clean there.

 

The lift pump feels as it always did, it's definitely not lacking it's usual resistance. I haven't cranked the engine yet. Won't this suck air into the injector pump and mean I'll have more bleeding to do later on than is necessary? Obv if I need to then I need to, but from what you're saying the lift pump doesn't indicate that this is the problem.

 

There are 2 fuel cocks and both are definitely now open.

 

I don't think the pump is ejecting air from the bleed points, or certainly not a noticeable amount, it appears to just be doing nothing.

 

In terms of cleaning the strainer and tray on the pump, would this be done by removing the top screw on the pump? I've read in other posts that bleeding through this one is most risky for a novice, and adjusting it incorrectly can lead to issues or something along those lines? I'm definitely not an expert in this stuff so only really want to try things if there's little/no risk involved, otherwise will call a mechanic.

 

When you say blowing back into the tank, is it possible to clarify what you mean by this? I.e. what would I actually be physically doing. A novice as I say!

 

Blockage in the pipes or diesel bug sound far more worrying. Is it naive to assume that because the engine was all working absolutely perfectly before I messed with the fuel filter that this is unlikely to be the case?

 

Would it be a stupid thing to do to loosen the nut where the fuel pipe from the tank joins the pump to check whether diesel is coming down that and definitely getting into the pump in the first place?

 

Thanks again, and apologies if I'm asking stupid questions.

I did not say crank the engine, just turn it over slowly with a spanner. Anyway once the  low pressure side is bled the high pressure side is a breeze. Loosen injector pipe unions, spin on starter, when the unions spit or  dribble tighten them.

 

That is the bleed screw on top of the injector pump, not the lift pump. As long as you are not ham fisted and ensure you do not move the bolt that bleed screw fits into you can use it but you need to get fuel flowing from the filter head first. 

 

It can be very difficult to start the pump union threads so use the flexible if you can, maybe your flexible goes straight into the pump and if so the flexibility makes it far easier to start the thread.

 

Have you tried blowing back into the tank yet? If not you really don't know if the pick up pipe is blocked or cracked.  I would split the fuel supply pipe at the end of the flexible I hope you have between hull and engine. You may find fuel leaks by gravity from there. Stick your mouth around the end of the pipe and blow but if diesel runs out steadily the pipes are probably clear to there.

 

I certainly could not totally rule out bug but it is less likely than other causes.

[Alan de Enfield]

1 hour ago, Sam T said:

There is no filter between the tank and the fuel pump so nothing to clean there.

 

2 hours ago, Sam T said:

I've changed my fuel filter on a bmc 1.8 this morning, which I 've done before no problem at all.

 

Where is this filter that you have changed ?

 

The principle idea of a filter is to avoid 'muck' getting into your pump and the rest of the system. It would be unusual to have no filter between the fuel tank and the pump.

[Sam T]

Thanks again.

 

Sorry I misunderstood what you were saying about blowing into the breather. I have now done that which caused diesel to flow freely out the top of the fuel pump. Didn't really think that through so now have quite a lot of diesel on the floor of my engine bay

 

So good that there is no blockage and was just an airlock in that pipework.

 

Even still, I cannot get the lift pump to do anything for now.

 

Still reading through the rest of the suggestions and will see where I get to.

Quite likely posting in here again in half hour or so.

 

Thank you so much

Edited August 17, 2019 by Sam T

[Sam T]

Still a bit stumped by it all. There is definitely fuel flowing to the pump now, but the lift pump just doesn't seem to do anything. Loosening the outlet pipe directly from it and pumping there's still nothing coming out and definitely none getting to the filter.

 

I cranked the engine a little as wasn't 100% confident how to turn it manually, and that's made no difference to the lift pump operation.

 

I didn't 100% follow what you were saying about disconnecting the feed pipe and blowing down there. Would that only have been necessary if blowing down the breather hadn't worked?

[Boater Sam]

Have you turned the engine with a spanner on the crank pulley for a full turn yet? Your calor spanner may fit.

I reckon the fuel lift pump is on the peak of the cam and that's why it wont pump.

[Sam T]

I have now but didn't seem to make any difference

 

However I also disconnected the filter top input from the pump to see if anything was actually coming out there while I pumped it. And it now is, but at a very very slow rate. Maybe a drop or two per pump, so will take forever to fill the fuel filter at that rate, though should be doable.

 

What kind of rate might you expect the lift pump to move fuel?

[Tony Brooks]

6 minutes ago, Sam T said:

I have now but didn't seem to make any difference

 

However I also disconnected the filter top input from the pump to see if anything was actually coming out there while I pumped it. And it now is, but at a very very slow rate. Maybe a drop or two per pump, so will take forever to fill the fuel filter at that rate, though should be doable.

 

What kind of rate might you expect the lift pump to move fuel?

 

With the conventional BMC lift pump the flow rate from the pump with the cap off should be zero because the diaphragm will just suck air.

 

If the cap on the lift pump is not 100% airtight it will not pump. The airtightness includes the rubber O ring    that may have swollen and is retained in the cap  and whatever form of soft washer that is on the centre cap bolt.

 

Put everything back together and then totally take out the banjo bolt that holds the leak off pipe(s) to the filter head. Then try pumping the lift pump.

[Sam T]

Everything is back together. I did as you said taking the banjo bolt out and pumped but still nothing. What was supposed to happen? I've put it back on now anyway as didn't want to lose washers etc.

[Tony Brooks]

28 minutes ago, Sam T said:

Everything is back together. I did as you said taking the banjo bolt out and pumped but still nothing. What was supposed to happen? I've put it back on now anyway as didn't want to lose washers etc.

If the pipework and pump head were airtight lots of fuel should have EVENTUALLY flowed from the open hole. I assume that you have put a bubble of spit across the hole to see if any air is being expelled.

 

If you have free flowing fuel to the pump inlet when you blow into the breather but nothing from the top of the filter with the bolt removed it implies that you have an air leak into the suction side of the system (tank to lift pump outlet, the flit pump has failed by falling apart inside or the diaphragm has split but why now I have no idea (see below), the pump operating lever is still on the top of the drive eccentric (but it should still pump a little) or you have not pumped properly -  long slow full travel strokes, not pump as  fast as you can.

 

The DPA injector pump does have a vane type transfer pump in side it and although it is not supposed to I think that with a narrowboat, a fullish tank of fuel in the normal position and  no air leaks that transfer pump just might hide a faulty lift pump until you need to bleed it.

 

To test the lift pump but beware that the rigid metal pipes can make it hard to refit the pipe unions.

 

1. Remove both the inlet and outlet pipes on the pump.

2. Make sure you can feel spring pressure for almost all the priming lever's full stroke. If not turn the engine over until you can.

3. Thumb over pump inlet and prime for about 30 seconds & release thumb - you should have a good suction under your thumb.

4. Repeat but this time keep your thumb in place for a slow count to 20 - there should still be suction when you release your thumb.

5. Repeat 3&4 but this time with your thumb over the outlet - this time you are looking for air pressure.

 

If you get no air pressure, no suction or neither pressure or suction then either the pump is faulty or there is an air leak, typically from the cap seal or centre bolt.

 

In that case any motor factors should be able to supply you with a Facit electric fuel pump and some fuel hose& clips so you can temporarily bypass the mechanical lift pump. Alternatively you may be able to rig a temporary high level "day tank" and bleed it by gravity to see if it will bleed OK. If yes it again suggest a problem in the lift pump area.

 

Edited August 17, 2019 by Tony Brooks

[Sam T]

Thanks Tony.

 

I'm getting there and you were dead right about the pump not being airtight when I put it back together.

 

I took it apart again, wiggled the seals around and then maybe did it up a bit tighter and that side of things is all working now. Have bled the filter top so squirts out fuel and no air.

 

Of course now having trouble with bleeding the high pressure side.

 

I've loosened the bolt on the injector pump which squirted out a lot of fuel when I cranked the engine.

 

Having tightened that back up it still won't start.

 

Loosened a few of the bolts on the injectors and cranked again, but no fuel coming out of those. There should be right? Is there something I'm missing here or another point I need to bleed first? Of course conscious of draining my starter battery now.

 

Thanks.

[Tony Brooks]

9 minutes ago, Sam T said:

Thanks Tony.

 

I'm getting there and you were dead right about the pump not being airtight when I put it back together.

 

I took it apart again, wiggled the seals around and then maybe did it up a bit tighter and that side of things is all working now. Have bled the filter top so squirts out fuel and no air.

 

Of course now having trouble with bleeding the high pressure side.

 

I've loosened the bolt on the injector pump which squirted out a lot of fuel when I cranked the engine.

 

Having tightened that back up it still won't start.

 

Loosened a few of the bolts on the injectors and cranked again, but no fuel coming out of those. There should be right? Is there something I'm missing here or another point I need to bleed first? Of course conscious of draining my starter battery now.

 

Thanks.

 

Of course it won't - you bled the low pressure side, you should bleed the injector pump bleed points by using the priming lever on the lift pump if you want to try to avoid bleeding the high pressure side. When bleeding from the injector pump always keep bleeding for at least 30 seconds after you think  you have all the air out. You can get slugs of air in the pipes.

 

Now loosen about half to one turn the four LARGE nuts on the injectors. Then get someone to crank the engine on the starter until those unions start to drip or spit. As they do tighten the applicable nut and the engine will be running before you get the last one done up.

 

I think there is still air in the system. What you got out was probably the fuel that was in the body of the injector pump as you pumped air into it. Bleed the pump again but this time use the priming lever and keep pumping well after you think its done. Then bled the injector unions. The same probably applies to the filter head.

 

Edited August 17, 2019 by Tony Brooks

[Sam T]

Thank you. Will try again now

[Sam T]

It's up and running and all looks to be perfect.

 

Thank you all so much to everyone that advised today and for being so patient with me, I realise it's probably a bit frustrating when you know exactly how to do it yourselves.

 

It's massively appreciated

[Alan de Enfield]

2 minutes ago, Sam T said:

It's up and running and all looks to be perfect.

 

Thank you all so much to everyone that advised today and for being so patient with me, I realise it's probably a bit frustrating when you know exactly how to do it yourselves.

 

It's massively appreciated

 

 

[Sam T]

3 hours ago, Alan de Enfield said:

 

 

Where is this filter that you have changed ?

 

The principle idea of a filter is to avoid 'muck' getting into your pump and the rest of the system. It would be unusual to have no filter between the fuel tank and the pump.

Realise I never responded to this question. There is definitely no fuel filter between the tank and the fuel pump. The one I have changed previously and today is after the fuel pump.

 

When I first got the boat a few years ago I had a mechanic come and service the engine for the first time and talk me through everything as he did it so I could do myself in future. As he never mentioned that there was anything odd about the set up or there should be another filter it's not something I'd ever given thought to.

 

The principle of what you're saying makes complete sense. When you say it would be uncommon not to have an initial filter, is that to say that some boats don't and its fine or that I really ought to be getting one fitted for the sake of my engine?

[rusty69]

10 minutes ago, Sam T said:

 

The principle of what you're saying makes complete sense. When you say it would be uncommon not to have an initial filter, is that to say that some boats don't and its fine or that I really ought to be getting one fitted for the sake of my engine?

Our boat has only ever had the one filter connected after the lift pump.I have always known this isn't really ideal, so a few weeks ago fitted one of these, before the lift pump (thanks @gazza):-

 

 

 

https://www.ssldieselparts.co.uk/aluminium-sedimenter-double-dfas1-p-722.html

 

 

Edited August 17, 2019 by rusty69

[Sam T]

Thanks, will look into it

[rusty69]

If nothing else, it will prolong the life of the smaller filter.

 

If you haven't already found it, Tony B's excellent website describes how these things work:-

 

http://www.tb-training.co.uk/13bfuel.htm#bmn48

[Alan de Enfield]

19 minutes ago, Sam T said:

The principle of what you're saying makes complete sense. When you say it would be uncommon not to have an initial filter, is that to say that some boats don't and its fine or that I really ought to be getting one fitted for the sake of my engine?

I can only relate to 

1) My experience

2) Engineering practices.

 

 

1) I have had 18 boats and helped many friends sort out things and I have never seen a boat without a filter before the pump.

 

2) The idea of having a filter is to 'catch muck' before it can get anywhere that 'muck' can cause a problem (blocking pumps, etc etc). You catch it early and it ensures that only clean fuel gets where it should.

 

In an ideal world you would have an agglomerator to remove the water from your fuel, as well as filtering the fuel. Water gets in to the tank either from the seller not keeping the fuel 'well', from condensation due to having your tank less that 'full', or even rain bouncing up and going down the vent. Water in fuel is BAD.

 

An example :

 

https://www.ebay.co.uk/itm/273858137582