Fuel problem - Perkins 4108

[neil1967]

This morning I left our marina under motor, but after no more that 5 mins the Perkins 4108 surged a couple of times and then stopped and would not restart - classic fuel starvation or air in fuel symptoms. I quickly dropped anchor, but at first sight I couldn’t see any problems. I then switched on an electric fuel pump that is in line before the lift pump and left it running for a few minutes and then successfully restarted the engine and returned to the Marina (leaving the electric pump running). On closer inspection I found a small fuel leak coming from the joint between the fuel return line and the top of the engine fuel filter. I tightened the banjo bolt and there is now no leakage and the engine has now run for about 30 minutes using the normal lift pump, with no problems. Now for the question - Is it likely that the small leak at the top of the fuel filter was the cause of an air leak which stopped the engine, or is this just an unfortunate coincidence and so I need to look deeper for a problem?

 

[38mess]

Any leaks in the fuel system doesn't help, but you seem to have answered your question.
A friend of mine got back to harbour when his engine stopped for seemingly no reason by by passing the filters with a jerry can of fuel and rubber pipe straight to the injector pump.
Ok in an emergency

 

[rogerthebodger]

I had issues with banjo bolts on my fuel system that tool some finding. eventually replaced all the copper washers with Dowty washers which fixws the problem

 

[yotter]

Glad its all sorted now, but said the leak was
between the fuel return line and the top of the engine fuel filter. I think that the fuel return line is under positive pressure, meaning that it may leak diesel out and into your bilge but the engine would still run. Perhaps the leak was between the fuel filter and the injection pump, that would make more sense to me. I am more familiar with VP but Perkins are not that different.
Angus

 

[neil1967]

Glad its all sorted now, but said the leak was
between the fuel return line and the top of the engine fuel filter. I think that the fuel return line is under positive pressure, meaning that it may leak diesel out and into your bilge but the engine would still run. Perhaps the leak was between the fuel filter and the injection pump, that would make more sense to me. I am more familiar with VP but Perkins are not that different.
Angus

Angus, that was my thought too, but I wonder if while the engine was sitting unused for about 10 days some air might have leaked in to the top of the filter housing and then been sucked through, hence the engine stopping after 5 mins or so. Running the electric pump might have purged the air from the system?

 

[oldharry]

I found the hard way that if the return line banjo is leaking, in spite of the positive pressure on the return line, it can still draw enough air in to cause running problems. I assume it was because the pulsing of the lift pump was creating sufficient negative pressure on each stroke?. Securing it solved the problem as it seems to have done for OP. I would want to run up under load for 5-10 minutes (i.e in gear while still tied up) before trusting it, as long as the prop wash doesnt disturb the marina neighbours too much!