Still no joy

[Benno 1688]

Hi my BMC 1800 is still reving as if it is searching for fuel. I have changed all the pipe work,and put new fittings and olives on. I have put a new lift pump on and checked the fuel pick up for blockages . It still revs up and eventually cuts out. I bleed it from the bleed nut on top of the pump and it starts any ideas what to do next.

[bizzard]

Hi my BMC 1800 is still reving as if it is searching for fuel. I have changed all the pipe work,and put new fittings and olives on. I have put a new lift pump on and checked the fuel pick up for blockages . It still revs up and eventually cuts out. I bleed it from the bleed nut on top of the pump and it starts any ideas what to do next.

How much fuel in the tank? Its possible that the fuel pickup dip tube in the tank, ''usually steel'' is corroded and has holes rotted in it above the normal pickup opening at the bottom and so drawing in air. It would be worth rigging up jury rig, Say a gallon can of fresh diesel and stand it near the engine and connect a length of fuel tubing to the lift pump inlet port with the other end in the can of diesel. Maybe a little bleed will be needed to start up.

Edited July 20, 2016 by bizzard

[ditchcrawler]

How much fuel in the tank? Its possible that the fuel pickup dip tube in the tank, ''usually steel'' is corroded and has holes rotted in it above the normal pickup opening at the bottom and so drawing in air. It would be worth rigging up jury rig, Say a gallon can of fresh diesel and stand it near the engine and connect a length of fuel tubing to the lift pump inlet port with the other end in the can of diesel. Maybe a little bleed will be needed to start up.

Actually that is a great way to bleed the system if you have gravity on your side. I have the ability to connect mine to the heating day tank which is higher than the engine.

[Tony Brooks]

If a gravity tank does not work and you are absolutely sure there is nothing floating about in the tank blocking the pick up then try this:

 

First remove the banjo bolt from the leak ff union on the top of the fuel filter. Make sure it is a hollow banjo bolt and that the 0.5mm hole in its side is not blocked.

 

Then:

 

Locate the fuel feed pipe from filter to injector pump, it should be the one on the end of the pump's culindrical body. The pipe union screws into a large hexagon.

 

Extreme cleanliness is now required and only use lint/hair free cloths.

 

Remove the fuel pipe and carefully unscrew the large hexagon. This is likely to hav e aspring under it but there should also e a plastic strainer. over the years these can become blocked so make sure it is clean and also that the washers that seal the hexagon are in good order.

[Benno 1688]

Hi Tony I did remove the hexagon fitting , when I put it back I could hear a spring. Do I need to remove the spring to get at strainer, if so how would you recommend removing it. I will look at the banjo first.

[Tony Brooks]

Hi Tony I did remove the hexagon fitting , when I put it back I could hear a spring. Do I need to remove the spring to get at strainer, if so how would you recommend removing it. I will look at the banjo first.

 

To be honest I can't remember but have a look here http://www.bluemoment.com/manuals/Lucas%20CAV%20DPA%20injection%20pump%20instruction%20book.pdf

 

Make sure you look at the hydraulic DPA diagram and not the mechanical one.

 

I am reluctant to suggest this but in the worst case you could take the whole end cap (4 screws) off so you can get at the regulating valve, springs and filter but I stress absolute cleanliness must be observed and swill everything out in clean diesel before reassembling it.

 

PS also look here http://www.solidebolide.nl/downloads/CAV%20Workshop%20Manual%20fuel-injection-pump.pdf Its for the mechanical version but has a better picture of the regulating valve and strainer.

Edited July 20, 2016 by Tony Brooks

[pete.i]

I don't know whether you have done this or not but there is a gauze filter in the top of lift pump. The fuel flows into the lift pump and the through the gauze filter. Mine was so blocked up that it was a wonder that any fuel got throught to the engine.

 

Ah just noticed that you have fitted a new lift pump so forget that.

Edited July 20, 2016 by pete.i

[Benno 1688]

Well I nave checked the banjo on top of the filter that was clear, I removed the hexagon nut and pulled out the spring and the little plastic filter. There was a small amount of dirt so I cleaned it. The pick up from the tank is ok there is a full tank of diesel, I have replaced all the pipes and fittings and it still doing it. I have run out of ideas and I'm slowly losing interest.

[bizzard]

Well I nave checked the banjo on top of the filter that was clear, I removed the hexagon nut and pulled out the spring and the little plastic filter. There was a small amount of dirt so I cleaned it. The pick up from the tank is ok there is a full tank of diesel, I have replaced all the pipes and fittings and it still doing it. I have run out of ideas and I'm slowly losing interest.

Do the the jury rig gallon can thing as I explained. It will eliminate the pipework back to, and the tank. If it still does it its something on the engine doing it.

The pick up pipe in the tank might be rusted and perforated towards the top.

[Tony Dunkley]

Do the the jury rig gallon can thing as I explained. It will eliminate the pipework back to, and the tank. If it still does it its something on the engine doing it.

The pick up pipe in the tank might be rusted and perforated towards the top.

 

. . . . . or cracked where it emerges from the fitting just inside the tank.

[bizzard]

I once had a mean customer with an old York engined 35cwt Transit. He said that the engine started holding back and then stopped when the fuel gauge showed 1/4 full. I diagnosed it as the tanks pick up pipe getting rusted and eaten away at the bottom. Oh! he said in that case I'll always keep more fuel in it to keep it above the quarter marker. As time went on the pipes corrosion gradually crept up, it got to having to keep the tank 1/2 full and then 3/4's full and then almost full and got to the stage where he had to stop at virtually every garage to keep the tank topped up and full to the brim. He eventually admitted that it needed fixing, so I did it. A new tank unit with pick up pipe was only, I think about £11 odd plus fitting.

[Tony Dunkley]

I once had a mean customer with an old York engined 35cwt Transit. He said that the engine started holding back and then stopped when the fuel gauge showed 1/4 full. I diagnosed it as the tanks pick up pipe getting rusted and eaten away at the bottom. Oh! he said in that case I'll always keep more fuel in it to keep it above the quarter marker. As time went on the pipes corrosion gradually crept up, it got to having to keep the tank 1/2 full and then 3/4's full and then almost full and got to the stage where he had to stop at virtually every garage to keep the tank topped up and full to the brim. He eventually admitted that it needed fixing, so I did it. A new tank unit with pick up pipe was only, I think about £11 odd plus fitting.

 

If that was the only problem he had with a York engine, then he wasn't just tight fisted, . . . he was extremely lucky.

[Benno 1688]

Hi tried the jury tank no joy, my thoughts are now with the stop valve .this is because when I pulled the stop the cable snaped and even though it ha a strong return Spring it did nor open again. Any suggestions greatly recieved, could I be barking up the wrong tree with the stop valve.

[Tony Brooks]

Stop valve?

 

The stop control on DPA hydraulic pumps simply lifts the governor valve into the no fuel position. When you return the arm to the run position a spring pushes the valve to maximum fuel.

 

Disconnect the stop cable from the pump lever and move the lever by hand.

 

More thoughts:-

 

On hydraulic DPA pumps the governor valve is moved by fuel pressure in the pump body. This varies with speed of the transfer pump plus the regulating valve position (see Tony's reply to the other BMC topic of today). If the regulating valve is sticky or the springs are faulty it might allow the transfer pump to over pressurise the pump body, closing the governor valve.

 

The same might also happen if the non-return/PRV valve on the return from the injector pump into the filter head is full of muck or jammed shut.

[Benno 1688]

Thanks Tony's, how easy or not is it to remove the pump. Then I could take it to the local diesel specialist to have it tested.

[Tony Brooks]

Don't do that until you rule out everything else.

 

Changing a 1.5 and probably a 1.8 DPA pump is easy as long as you can get access to all three mounting screws. I think I had a special home bent spanner for one of them.

 

Look at the triangular pump mounting flange and one corner, by a mounting slot, should have a line scribed on it. I think its the top right looking down the length of the pump. There is a similar cast steel plate mounted on the engine but in this case there is an adjustable pointer that should line up with the scribed line. Make sure it does or if it is missing use a centre punch to make a witness mark in the cast steel plate that .line sup with the scribed line.

 

Remove all the pipes plus throttle and stop cables.

 

If the pump has a cable mounting plate or brackets fitted to its cylindrical end remove it.

 

Undo the three mounting nuts and the pump will need a good hard tug to pull it out of the engine. If the gasket has stuck it may need a bit of rocking or the CAREFUL use of a lever.

 

Fitting is the reverse, making sure the line and pointer are aligned but make sure the people who overhaul the pump rescribe the line when it is on their test rig.

 

Please look at the other threads (may be in "Others" and involve a Perkins) for links to the DPA "manuals".

[Benno 1688]

Hi Tony I'm not sure what else I can do. A friend who rebuilds race engines for go karts has suggested that when the engine is ticking over spray carb cleaner on all the joints and if it revs then that's where the air leak will be. I will try that however I'm not convinced that it's a Leakey joint as I have replaced them all along with thr lift pump and all the pipes. The non return valve you speak of is that something that I could do if so how.

[Tony Brooks]

Hi Tony I'm not sure what else I can do. A friend who rebuilds race engines for go karts has suggested that when the engine is ticking over spray carb cleaner on all the joints and if it revs then that's where the air leak will be. I will try that however I'm not convinced that it's a Leakey joint as I have replaced them all along with thr lift pump and all the pipes. The non return valve you speak of is that something that I could do if so how.

 

To be honest if you are taking advice from a petrol mechanic on how to find a leak in the FUEL system when the advice seems to be for how to find leaks on a PETROL engine inlet manifold I might as well give up and leave the pair of you to it.

 

Have you disconnected the stop cable and ensured the stop lever is in the run position? If not do it now, that will show if it is the stop control or not.

 

The non-return valve is a long hexagon screwed into the filter head by an arrow pointing into the filter. The return form the pump is screwed into that by a much narrower hexagon.

[bizzard]

The engines fuel filter unit is probably the most tampered with thing on the engine fuel system, what with filter changing, bleeding and so on/ For that reason it might be worth scrutinizing it very very closely indeed for any faults, like correctly fitted filter bowl and sealing ring if not a spin on type, all joints and washers and with a magnifying glass for possible hair line crack in the casting, ''not particularly unusual''.

It might be worth removing it to examine it properly, inside and out.

Edited July 23, 2016 by bizzard

[Benno 1688]

To be honest if someone told me to run around my mooring with some pants on my head singing merry Christmas I would do it as I'm that desperate to fix the problem. I will check the non return valve and the filter also I will have a look at the stop..

[Tony Brooks]

The engines fuel filter unit is probably the most tampered with thing on the engine fuel system, what with filter changing, bleeding and so on/ For that reason it might be worth scrutinizing it very very closely indeed for any faults, like correctly fitted filter bowl and sealing ring if not a spin on type, all joints and washers and with a magnifying glass for possible hair line crack in the casting, ''not particularly unusual''.

It might be worth removing it to examine it properly, inside and out.

 

Take special care to inspect whatever seals the bolt that holds the filter together. Some use a soft washer while other use an O ring and some after market filter O rings are made of "rubber" that is too small in section. maybe buy a genuine Lucas/CAV/Delphi 296 filter and change it while you are inspecting the components. However I seem to recall that you said that you had changed the filter before.

 

If the filter bolt is sealed with a soft washer then a new one could be a good idea.

[Benno 1688]

How would I check the none return valves.

[Tony Brooks]

How would I check the none return valves.

 

Take it out, make sure no muck is lodged in it,poke it with a bit of wood or plastic to make sure the valve will actually move. Then try blowing through it to make sure it seals.

[mross]

TB Kudos for your endless patience and courtesy. So many repeated queries and never a cross word.

[Benno 1688]

Been down to the boat this morning done the stop disconnected the cable and checked it I'm happy that it's ok. Put a new non return valve on the filter and a new rubber o ring on the filter bolt. Ran it for about five minutes and it started to rev up again. It ticks over with no problems as soon as I put some revs on it starts.