BMC 1500 cutting out. Video

[Fergalb]

Hi all new here and new to BMC's hopefully someone can help me out, my engine runs fine on low revs but on the higher revs it cuts out, sometimes it seems like I have to wait till the engine cools down before it will restart and other times it starts back up. In the video you can see it trying to cut out at 3:43 min  and then at 7:30 min's it cuts out, after a bit of work I took out the thermostat to see if was because of overheating but it made no difference, getting 250 compression on all cylinders. This boat was under the water for 7 weeks but I'm not sure if that caused any damage.  Any help would be most welcome thanks.          

 

[Tony Brooks]

I am not running a video on mobile broadband.

The normal thing to suspect is a fuel problem, especially if it revs a sit stops.

Is the tank breather free? If blocked it will make a vacuum in the tank and stop the engine.

How much fuel is there in the tank. The bottom portion should be below the pick up point so I would suggest anything below 6" be considered as empty.

When were the the fuel filters last changed/checked? If a long time they could be blocked if a short time a seal may be displaced - ditto the strainer under the lift pump cap.

Then its check all fuel pipe  joints and make sure you can blow back down the pipe into the tank.

 

 

 

[Eeyore]

3 minutes ago, Tony Brooks said:

I am not running a video on mobile broadband.

The normal thing to suspect is a fuel problem, especially if it revs a sit stops.

Is the tank breather free? If blocked it will make a vacuum in the tank and stop the engine.

How much fuel is there in the tank. The bottom portion should be below the pick up point so I would suggest anything below 6" be considered as empty.

When were the the fuel filters last changed/checked? If a long time they could be blocked if a short time a seal may be displaced - ditto the strainer under the lift pump cap.

Then its check all fuel pipe  joints and make sure you can blow back down the pipe into the tank.

 

 

 

Have watched the video for you Tony ;-)

At 3:43 min the engine can be heard to increase in revs before spluttering and then regaining revs.

At 7:30 min the engine dies from high revs with no preceding rise in revs; almost as though the stop control had been operated.

Steve

[Fergalb]

Thanks for the reply Tony, I ran it with the fuel cap off and it still stoped, 3/4 of a tank of fuel and all new filters, not sure about the strainer under the lift pump cap where would I find that, I just want to check everything before I take off any pipes as I found it a bit of a pig to bleed.  

[Tony Brooks]

Left hand side of the engine below the manifolds and about 1/4 way back from the front. There are variations but usually thee is a domes cap held on with a  single bolt.

 

Turn the fuel tap off before taking the cap off and turn it back on fully when done and before bleeding the system

Do NOT remove the rubber seal from the cap. They swell and can be impossible to get back in.

Make sure you clean the sediment trap that is below the stainer.

"All new filters" - I bet its a misplaced, twisted, or left out seal - especially if its one with an O ring around the centre bolt.

Any centre bolt on the fuel system that uses a soft washer to seal should have a new soft washer fitted when it has been distured.

 

[bizzard]

Was the tank and its filler and breather submerged for 7 weeks too ? If so  all sorts of muck and perhaps fuel bug in the tank now. It would probably need steam cleaning out.  I'd fix up a jury rig tank or can of diesel hung above the engine and connect it to the the lift pump inlet port.  Under the lift pumps domed top is the filter gauze, remove centre bolt lift off the dome and pick the filter out to clean it. Below the filter gauze is a compartment which catches the muck that the filter filters out, blow it out with compressed air or with a tube by mouth. Don't touch the rubber seal under the domed top unless you have a new one to replace it with. There should also be a tiny O ring or fibre washer under the bolt head. Go easy, don't over tighten it when reasembling.

[Fergalb]

Thanks for the replies guy's, The tank was fully cleaned out and new fuel added " I did use road diesel not sure if the lack of sulphur would be a problem" I changed the filters on the left and right of the engine maybe I'll check them incase I missed something, a rig tank is a good idea should tell me if the problem is between the tank and the injector or the injector itself.

 

   

[bizzard]

Looks nice and clean now. Looks like the bleed screw is missing on that filter unit. Yes, as you say a jury rigged tank would by-pass the pipework to and the fuel tank.

[RLWP]

55 minutes ago, Eeyore said:

Have watched the video for you Tony ;-)

At 3:43 min the engine can be heard to increase in revs before spluttering and then regaining revs.

At 7:30 min the engine dies from high revs with no preceding rise in revs; almost as though the stop control had been operated.

Steve

Sounds like an air leak into the fuel line. That increase in revs is what happens

Richard

[Fergalb]

14 minutes ago, bizzard said:

Looks nice and clean now. Looks like the bleed screw is missing on that filter unit. Yes, as you say a jury rigged tank would by-pass the pipework to and the fuel tank.

 

14 minutes ago, bizzard said:

Looks nice and clean now. Looks like the bleed screw is missing on that filter unit. Yes, as you say a jury rigged tank would by-pass the pipework to and the fuel tank.

Yep she looks a bit better now compared to when I got her.

 

[croftie]

That's a difference and a half, well done.

[Chop!]

We got exactly the same symptoms, caused by water and diesel bug in our tank, when we ran straight from a five litre container, we had no problem, had the diesel 'polished' except they left over 18 litres of sludge in the bottom of our tank. Cleaned it out properly and the problems stopped. Good luck!

[Mikexx]

I'm wondering about the lift pump if this is still the original.

Does the lift pump have a mechanical lever? After stalling can you manually pump more fuel through? It takes a bit to get used to the feel of it, but I'm wondering if this is fuel starvation low pressure side? Which changing filters might help and/or the pump.

The fact it starts OK after stall suggests there isn't air in the HP side or it would never restart without bleeding. Air can accumulate on the LP side and I would be tempted to release the banjo on the main filter to see if any bubbles come out after pressurising the LP side by operating the lift pump. If not then I don't believe any air is getting in.

I'm puzzled it restarts so easily.

[Fergalb]

It has a manual pump on it thats how I bled it after changing the filters and cleaning the tank it took a  hell of a lot of pumping to fill it up so maybe it is sucking in air somewhere. Sometimes it takes up to half an hour before it will start up and other times it starts first turn of the key. At the end of the video you can see the temp jump up I thought that might be affecting the injector pump or the temp might just be going up because no water is being pumped when it's stoped.   

[Tony Brooks]

Are you aware that you also have primary filters (agglomerators) of water traps (sedimentors) as well as the engine filters. from what I can see they are sedimetors with no filter in them, just a cone.

[Mikexx]

2 hours ago, Tony Brooks said:

Are you aware that you also have primary filters (agglomerators) of water traps (sedimentors) as well as the engine filters. from what I can see they are sedimetors with no filter in them, just a cone.

I would hope the sedmimentor would have been dismantled and cleaned. The OP does mention "filters"?

Do you think this is a water in fuel problem? I feel changing the filter/taking the filter assembly apart and looking what's in it might be a wise move?

[Tony Brooks]

I think checking the seals on the filter and sedimentor would be a wise first move as well - after checking the lift pump strainer!

[Fergalb]

Thats sounds like a plan just not looking forward to priming the system again  is there a way of pressure testing it and then look for leaks or listen for air escaping, would pumping the manual  pump build up compression or would it just force it into the injection pump, sorry for the silly questions this is my first diesel engine  I'm more used to outboards and V8's 

[Tony Brooks]

You could seal the tank breather and cobble a tyre valve onto the breather and pressurise the tank but the problem is not anything leaking out, it is likely to be air leaking in and that is much harder to find..

The maximum the lift pump will produce is about 6psi, then it just stops pumping.

If the priming lever on the lift pump has lots of slack and very little pump when starting bleeding  then turn the engine over about  one full turn, then it should be lot of pump and little slack. If it goes slack while bleeding stop pumping so fast or open the bleed screw more. My students always primed too fast at first so I advised that they get mum to make them wear boxing gloves at night.

First bleed point is the banjo union on top of the filter that holds the leak off pipe.

Second bleed point is the 8mm hexagon on the SIDE of the pump body. Keep priming for at least 30 seconds after you think you have got rid of the air.

Third belled point is the large unions on the injectors and spin the engine on the starter until they drip or spit. Only loosen a turn or less, no more

[Fergalb]

7 hours ago, Tony Brooks said:

You could seal the tank breather and cobble a tyre valve onto the breather and pressurise the tank but the problem is not anything leaking out, it is likely to be air leaking in and that is much harder to find..

The maximum the lift pump will produce is about 6psi, then it just stops pumping.

If the priming lever on the lift pump has lots of slack and very little pump when starting bleeding  then turn the engine over about  one full turn, then it should be lot of pump and little slack. If it goes slack while bleeding stop pumping so fast or open the bleed screw more. My students always primed too fast at first so I advised that they get mum to make them wear boxing gloves at night.

First bleed point is the banjo union on top of the filter that holds the leak off pipe.

Second bleed point is the 8mm hexagon on the SIDE of the pump body. Keep priming for at least 30 seconds after you think you have got rid of the air.

Third belled point is the large unions on the injectors and spin the engine on the starter until they drip or spit. Only loosen a turn or less, no more

Thanks again Tony for the tips I bet thats why I was pumping for so long lots of slack with little pump 

[Paul T]

Have you sorted this problem out, if not this may be something to check, i bought a boat with a 1.8 BMC that would not run for more than a few seconds, the revs would increase and it would die and would not run.

Eventually i found the problem to be what looks like a reducer from your fuel filter at the back of the rocker cover (from the picture i can't tell if you have one or not). It was actually a non return valve with a spring loaded ball bearing inside that had seized shut with rust and preventing a full fuel flow. My tank was higher than the lift pump and injection pump so i was able to do away with it all together and the engine ran fine but if your tank is low down and you have one fitted you will have to replace it. Maybe something worth looking at.

 

[Fergalb]

I think it was sucking in air on the low pressure so I fitted an electric fuel pump and now she is running fine.

[Paul T]

Glad you got it sorted, watch out for the non return valve though if you have one. Happy cruising.

P.S. nice roomy boat, did you buy from Richardsons (new Horizon)?

[Fergalb]

No I got her sunk in a local marina here in Ireland.

 

[Paul T]

Must have been a lot of work involved to bring it back to life.