New Nanni starting problems

[ColinR]

Hello, I wondered if the collective wisdom could shed any light on this as its driving me to distraction;

I had a new Nanni D21 professionally fitted last winter 2012/13. Apart from a problem with coolant leakage it has run faultlessly, never missing a beat. Starting from cold has been another story. When left overnight or longer it has been a problem to start. It fires, dies; fires, dies; fires and runs for a few seconds then dies and after doing this several times runs perfectly. Clearly air is getting into the system when left for a while. I have checked and tightened the jubilee clips on the fuel lines endlessly, occasionally found a trace of diesel on my fingers when feeling around the connections but no actual leaks.

Lately the engineer has been making repeated attempts to fix the problem. He replaced the primary filter, then disconnected the entire fuel system and fed it from a temporary tank placed higher than the engine to see if there are leaks on the engine side of the primary filter. The engine always started fine during this process. Then he disconnected the Eberspacher which is fed from the primary filter to see is that was causing the problem, then reconnected it and ran it all for a while. No problem with the Eberspacher. In fact he couldn’t find a problem and it always started perfectly when he tried it.

So I have spent the weekend aboard, used the heater a lot in the evenings. First couple of days the engine started on the button from cold, then next day same old problem starting it. Likewise today.

Briefly the system is S/S tank mounted under the cockpit sole so the fuel flows down to the primary filter which is the lowest point in the system, then up to the lift pump and from there up to the secondary filter and injectors. From the primary filter the fuel flows up to the Eberspacher pump and up more to the heater itself which is the highest point in the system. The fuel comes out the top of the tank via a dip pipe or whatever it’s called.

I have assumed that air is getting in when left overnight. But now I am wondering if air can be building up in the pipes when it is running and slowly migrating to the injectors when it’s left for a while. But I’m no engineer so this is speculation. Anyhow I have motored for many hours with no problem at all and it starts perfectly from warm.

Any thoughts much appreciated…

 

[robmcg]

The symptoms sound very much related to the fuel take off for your heating. If at all possible, your Eberspacher fuel supply should be independent of the boats engine fuel supply, ie not drawn from the primary fuel line or filter. Caveat with this is that others will be along to say, no, it's fine to take the supply from the engine primary filter, never did their installation any harm etc. Your symptoms are the same as 3 others I know of, all cured by putting the heating on an independent fuel supply - which is the recommended or preferred way of doing it.

 

[ColinR]

Thanks, this is certainly possible. But I had the same problem all last season and didn't use the Eberspacher at all during the summer. Are you suggesting it can cause problems even when not being used? Also from the primary filter it is uphill to the Eberspacher pump and heater unit so not sure how air could find its way down into the engine fuel line.

The symptoms sound very much related to the fuel take off for your heating. If at all possible, your Eberspacher fuel supply should be independent of the boats engine fuel supply, ie not drawn from the primary fuel line or filter. Caveat with this is that others will be along to say, no, it's fine to take the supply from the engine primary filter, never did their installation any harm etc. Your symptoms are the same as 3 others I know of, all cured by putting the heating on an independent fuel supply - which is the recommended or preferred way of doing it.

 

[robmcg]

If the Eber fuel supply is shared with the engine fuel supply, the engine fuel lift pump will overcome the 'uphill' element (in theory!)

 

[West Coast]

Share robmcg's view that heater fuel supply should be independent of the engine. We had a problem some years ago where the heater fuel supply was taken from the second outlet of the CAV filter unit, but this seemed to allow air to be drawn in somehow to the engine fuel line. Changing this to an independent feed to the heater, and blanking off the CAV filter sorted the problem.