Height of fuel pick up?/engine cutting out…

[hector]

Hi everyone - we’ve been stuck with an engine cutting out after about half an hour yesterday and the day before (stationary boat, cuts out quicker under load). This is actually after having the fuel cleaned so assumed that we just had some crud kicked up into the pipes that needed worked through, or air trapped.

 

the problems persisted through several attempts though, since Sunday afternoon.

 

the fuel cleaners actually took about thirty litres of filthy fuel away though  and I’ve been running the engine for a while… so it suddenly occurred to me to actually check the level. At first I thought it was fine as a good four inches left but after some further research it seems like the take up pipe could be that high? I had thought maybe an inch or two at most… 

 

so I guess the question is, have I solved the gunk/air in pipes issue and run out of fuel in the process 🫣

 

Thanks for any thoughts!

h. 

[Tony Brooks]

15 minutes ago, hector said:

Hi everyone - we’ve been stuck with an engine cutting out after about half an hour yesterday and the day before (stationary boat, cuts out quicker under load). This is actually after having the fuel cleaned so assumed that we just had some crud kicked up into the pipes that needed worked through, or air trapped.

 

the problems persisted through several attempts though, since Sunday afternoon.

 

the fuel cleaners actually took about thirty litres of filthy fuel away though  and I’ve been running the engine for a while… so it suddenly occurred to me to actually check the level. At first I thought it was fine as a good four inches left but after some further research it seems like the take up pipe could be that high? I had thought maybe an inch or two at most… 

 

so I guess the question is, have I solved the gunk/air in pipes issue and run out of fuel in the process 🫣

 

Thanks for any thoughts!

h. 

 

I always say allow 6" of unusable fuel, so you may well have done, but if you have not changed/cleaned your fuel filters/water traps/ any gaizes in the lift pump it would be wise to do so.

 

We don't know what engine so you may not have a gauze in the lift pump, but if Vetus you may have a filter in the end of it.

[Rob-M]

We had an issue where below half a tank of fuel it started cutting out and then after a couple of days failed to start.  This was eventually diagnosed as a failing fuel pump on our Vetus engine, with a nearly full tank the pump didn't have to do much to draw fuel through but as the tank got lower the pump started struggling until eventually it couldn't draw fuel through.

[hector]

Thanks both - that’s interesting it was doing this below half tank… Our engine is a Barrus Shire 40.

 

It’s a brand new filter, which I’ve since checked is seated properly and have bled that, and the injection points a few times.

 

there’s no independent water trap just a drip point on the bottom of the filter.

 

I’ll put 40L in in the morning and see where I get to if I bleed and prime the whole thing again.

 

in terms of fuel pumps what am I looking for? Bit of a novice with engine stuff. I don’t think there is a pump in the fuel line to the engine… but is there always one? The filter needs primed by hand on the filter header, and the engine needs turned over to check if the injection points are spitting (as opposed to just having the ignition on… which I gather is sometimes the case). 

 

h. 

[Tony Brooks]

I will defer to someone with a Shire engine, but I doubt its lift pump has a strainer in it, but I have known far eastern lift pump valves clog with diesel bug. That could give similar symptoms.

 

I find it very strange that a Shire that is generally thought of as a quality engine was not fitted with a water trap on the pipe that runs from tank to engine.

 

If an engine has an electric lift pump then usually just turning the ignition of does all the filter priming and low pressure bleeding for you. The fact you have a manual priming provision suggests that you do have a lift pump.

[Tonka]

15 hours ago, Tony Brooks said:

 

I always say allow 6" of unusable fuel, so you may well have done, but if you have not changed/cleaned your fuel filters/water traps/ any gaizes in the lift pump it would be wise to do so.

 

We don't know what engine so you may not have a gauze in the lift pump, but if Vetus you may have a filter in the end of it.

Our fuel tank is under the boatmans cabin floor. Would you still alow 6 inch of unusable fuel

[BWM]

One thing that is worth doing whilst you may be at the low fuel mark is to get a smooth piece of dowel, or other suitable material, and make a dip stick (marking the level of the fuel as it is now). You can then make another mark when 40 litres is added, giving you a useful guideline for the future. 

[Tony Brooks]

11 minutes ago, Tonka said:

Our fuel tank is under the boatmans cabin floor. Would you still alow 6 inch of unusable fuel

 

No, but you have, by modern standards, a non-standard boat so it behoves you to properly understand it. Depending upon tank depth you may have less than an inch for water build up and that makes for very regular bottom of  tank cleaning

[dmr]

1 hour ago, Tonka said:

Our fuel tank is under the boatmans cabin floor. Would you still alow 6 inch of unusable fuel

 

We got one like that on a Colecraft trad-trad. Its an integral tank.

Fuel pickup is just under 1.5" from the tank bottom but obviously yours might not be the same.😀

 

Tank is 8" deep so a 6" "reserve" would not be a good thing.😀

[n-baj]

I’ve had fuel starvation issues on a barrus shire a couple of months ago, randomly cutting out at any load (in idol, under load, didn’t matter), persisting after lift pump replacement and fuel/tank cleaning (which wasn’t the best of cleans as there was still gunk they didn’t shift). 
 

what cured it was I simply connected a hand pump to the intake pipe going into the tank and blow/suck through many times over. I surmised that there’s a sintered end on the pick up pipe and that was clogged.

[hector]

2 hours ago, n-baj said:

I’ve had fuel starvation issues on a barrus shire a couple of months ago, randomly cutting out at any load (in idol, under load, didn’t matter), persisting after lift pump replacement and fuel/tank cleaning (which wasn’t the best of cleans as there was still gunk they didn’t shift). 
 

what cured it was I simply connected a hand pump to the intake pipe going into the tank and blow/suck through many times over. I surmised that there’s a sintered end on the pick up pipe and that was clogged.

Yeah this was a first thought of mine too after having gunk stirred up… but I figured that would affect the filter priming process if it was jammed on the intake. I must have drawn a couple of litres through there over last couple of days.

 

I’ve just put 60 L in and it seems to draw into the filter with the primer very easily. 
 

Engine not yet run long enough to know if problem gone though 😕 

3 hours ago, BWM said:

One thing that is worth doing whilst you may be at the low fuel mark is to get a smooth piece of dowel, or other suitable material, and make a dip stick (marking the level of the fuel as it is now). You can then make another mark when 40 litres is added, giving you a useful guideline for the future. 

I have just done this, excellent idea! 

4 hours ago, Tony Brooks said:

I will defer to someone with a Shire engine, but I doubt its lift pump has a strainer in it, but I have known far eastern lift pump valves clog with diesel bug. That could give similar symptoms.

 

I find it very strange that a Shire that is generally thought of as a quality engine was not fitted with a water trap on the pipe that runs from tank to engine.

 

If an engine has an electric lift pump then usually just turning the ignition of does all the filter priming and low pressure bleeding for you. The fact you have a manual priming provision suggests that you do have a lift pump.

I’ve had another look and pretty sure there isn’t a lift pump. Fuel line seems to go from side of tank to the filter, then on a flexi hose to what I think is the throttle, then the distributor. 
 

something that I’ve taken for granted but someone pointed out is anomalous is that the feed to the heating is not on its own pipe from the tank, it branches off the same supply as the engine, between tank and filter (it has its own cartridge filter). I’ve currently got that line switched off on a stopcock though, as I figured it might be drawing rubbish or air backwards out of the heating system filter?

 

weirdly, though, there is a second copper pipe coming out of the tank, which meets a flexi hose and then disappears under the engine… (but doesn’t seem to be hanging loose, I just can’t see where it goes). Any thoughts what this is? Would a diesel tank have an overflow outlet into the engine bilge? 

[Tracy D'arth]

33 minutes ago, hector said:

Yeah this was a first thought of mine too after having gunk stirred up… but I figured that would affect the filter priming process if it was jammed on the intake. I must have drawn a couple of litres through there over last couple of days.

 

I’ve just put 60 L in and it seems to draw into the filter with the primer very easily. 
 

Engine not yet run long enough to know if problem gone though 😕 

I have just done this, excellent idea! 

I’ve had another look and pretty sure there isn’t a lift pump. Fuel line seems to go from side of tank to the filter, then on a flexi hose to what I think is the throttle, then the distributor. 
 

something that I’ve taken for granted but someone pointed out is anomalous is that the feed to the heating is not on its own pipe from the tank, it branches off the same supply as the engine, between tank and filter (it has its own cartridge filter). I’ve currently got that line switched off on a stopcock though, as I figured it might be drawing rubbish or air backwards out of the heating system filter?

 

weirdly, though, there is a second copper pipe coming out of the tank, which meets a flexi hose and then disappears under the engine… (but doesn’t seem to be hanging loose, I just can’t see where it goes). Any thoughts what this is? Would a diesel tank have an overflow outlet into the engine bilge? 

It will not be an overflow.

 

I would expect you to have a feed and a return to the tank. Have you been looking at the return rather than the feed?

[hector]

2 minutes ago, Tracy D'arth said:

It will not be an overflow.

 

I would expect you to have a feed and a return to the tank. Have you been looking at the return rather than the feed?

I’ve definitely been looking at the feed - but if there’s a return that would make sense. I didn’t realise there would be a return (or a reason for one). Thanks! 

[Tony Brooks]

1 hour ago, hector said:

I’ve definitely been looking at the feed - but if there’s a return that would make sense. I didn’t realise there would be a return (or a reason for one). Thanks! 

 

The return allows a small amount of fuel plus any air trapped in the fuel to return to the tank, rather than stopping the engine.

[Alan de Enfield]

1 hour ago, hector said:

I’ve definitely been looking at the feed - but if there’s a return that would make sense. I didn’t realise there would be a return (or a reason for one). Thanks! 

 

The pump provides more fuel than the engine can use so there is a return (usually to the tank, but occasionally to the 'big' fuel filter) for the excess fuel.

[David Mack]

7 hours ago, hector said:

I’ve definitely been looking at the feed - but if there’s a return that would make sense. I didn’t realise there would be a return (or a reason for one). Thanks! 

There will be a return pipe that is connected to the top of each of the injectors, and usually* goes back to the fuel tank.

 

*On some vintage engine installations it drains into a baked bean can strapped to the side of the engine which periodically has to be emptied back into the main tank.

[Tony Brooks]

18 hours ago, Alan de Enfield said:

 

The pump provides more fuel than the engine can use so there is a return (usually to the tank, but occasionally to the 'big' fuel filter) for the excess fuel.

 

For total accuracy that is not really true because the majority of mechanical lift pumps will "free wheel" if the engine needs less fuel than they will deliver, while electric ones don't draw the solenoid back for the next pump stroke until the fuel in the pumping chamber no longer holds the armature back. I am sure it is true for some though.

 

In the majority of cases the return is to vent any air in the fuel back to the tank.

 

 

 

[Chewbacka]

Something to consider.  On my boat the filler (and dipstick hole) is on the opposite side to the engine take off point.  If the boat lists a bit, then the fuel flows to one side, if it’s the dipstick side it can add an inch to the level and conversely drop the level on the ‘engine’ side.  Gives the impression there is a couple of inches more fuel for the engine than there really is.

[hector]

4 hours ago, Chewbacka said:

Something to consider.  On my boat the filler (and dipstick hole) is on the opposite side to the engine take off point.  If the boat lists a bit, then the fuel flows to one side, if it’s the dipstick side it can add an inch to the level and conversely drop the level on the ‘engine’ side.  Gives the impression there is a couple of inches more fuel for the engine than there really is.

Yeah I think this could have been a factor for sure. I need to stand on the same side as the take off point in order to change the filter and prime it, so I could have been sucking up fuel then, and then standing across from it, or levelling off, to leave the engine running.

 

At the moment we seem to be running (only one cut out since, dropping to idle when mooring, and it restarted straight away)... however immediate investigations after led to another issue I'd better restart a new thread on 😕 Thanks for you help everyone!