new engine starting problems

[ColinR]

I had a new Nanni 21 fitted last winter. Nice engine but I have had problems starting it when its been left for a week or two. Its fires immediately then dies and does this quite a few times before getting going. Clearly air is getting into the fuel line but the engineer has checked and rechecked all the connections and so have I . All seems tight and dry, no sign of a leak. It only happens when its not used for a week or so so I suspect a very slow leak but no idea how to find it. Any suggestions? Thanks, Colin

 

[Cymrogwyllt]

Worth trying Vaseline on the connections?

edit: without dismantling them.

 

[sailorman]

what has changed since it was installed.
fuel filter ????

 

[ColinR]

Primary filter was quite new so was not changed and everything on the engine side of that is new. C

 

[pvb]

Clearly air is getting into the fuel line but the engineer has checked and rechecked all the connections and so have I . All seems tight and dry, no sign of a leak.

I'm assuming, from your description, that the fuel tank is below the engine. If that's the case, I'm not sure that you'd see a leak, if the problem is air getting in to the system. It might be worth re-making all the joints, using a diesel-resistant sealant.

You say the primary filter wasn't replaced, but has the filter element been replaced since the new engine was fitted? Might there be an air leak on one of the seals?

Another possibility is that the engine lift pump has a fault, although it's not something you'd expect on a new engine.

 

[ColinR]

The tank is mostly above the engine so I'd expect some sign of weeping if a joint is allowing air in but all seems dry. C

 

[earlybird]

If the actual fuel level in the tank is above the fuel pipework to the engine, including the engine mounted filter, then that's a bit of a puzzler.
Does the fuel pipe connect to the bottom or to the top of the tank. Have you checked that connection, esp. if at the top?
However, I'd see the filters as main suspects, esp. if the primary is the common CAV296 type.

 

[ColinR]

If the actual fuel level in the tank is above the fuel pipework to the engine, including the engine mounted filter, then that's a bit of a puzzler.
Does the fuel pipe connect to the bottom or to the top of the tank. Have you checked that connection, esp. if at the top?
However, I'd see the filters as main suspects, esp. if the primary is the common CAV296 type.

Thanks for that. Filter is HDF296 and was indeed wet with diesel on bottom and top central bolt not tight. I have tightened it up and will monitor it. Hopefully this might be the problem. Thanks for the help. C

 

[Daydream believer]

Thanks for that. Filter is HDF296 and was indeed wet with diesel on bottom and top central bolt not tight. I have tightened it up and will monitor it. Hopefully this might be the problem. Thanks for the help. C

dry the surface really well then wrap the filter in absorbent paper such as ordinary kitchen roll or loo paper
you will see the stain if there is a leak when you leave it so can trace it easier

 

[pdur]

I had exactly the same problem after installing my Nanni 3.21. My tank is also situated above the engine and the advice of the A.R. Peachment was to instal a non-return valve between the injectors and the return feed to the tank - presumably to stop the fuel draining back through the injectors. I was dubious whether or not this would make any difference but an outlay of £5 on a valve has cured the problem. It now starts first time every time but more importantly it doesn't stall once started. Give it a go - it worked for me.

 

[geem]

Thanks for that. Filter is HDF296 and was indeed wet with diesel on bottom and top central bolt not tight. I have tightened it up and will monitor it. Hopefully this might be the problem. Thanks for the help. C

If its got a central bolt then I would swap the whole filter unit for one of the spin on types similar to an oil filter. These are much more reliable and easy to swap filters if you get a blockage. No more fiddly seals

 

[pmagowan]

Yes, I would replace the filter. I now use racors after many problems with the cav types. It is a lot easier than trying to pick all the bits out of the bilges every filter change.

 

[DaveS]

Yes, I would replace the filter. I now use racors after many problems with the cav types. It is a lot easier than trying to pick all the bits out of the bilges every filter change.

I've stuck with a CAV - partly because the filters are a lot cheaper so I don't mind keeping a good number of spares on board, partly because I like the glass bowl. I did, however, invest under £1 in a plastic kitchen measuring jug just a little bigger than the filter and bowl. To change filters I hold this under the bowl, undo the centre bolt, and drop everything into the jug. It then sits vertically on the cockpit sole while I sort out the bits for binning and the bits for cleaning and replacing, and finally it's got a pouring lip to make disposing of the diesel easy.