Lister Petter Generator Fuel Return Line Repair

The generator onboard Encore is a 10kW three cylinder Lister Petter. It was not original to the boat and was installed at some point during the mid ’90s. It had 1400 hours on it when Encore was purchased. During the last nine months since the boat has been back in the water, we have put a little over 500 trouble free hours on it. The oil and filters have been changed every 150 hours, and we replaced a faulty water temperature gauge. Other than the gauge replacement, no other non-planned maintenance has been necessary. The generator has performed very well.

The Problem

In early March 2021 while getting ready to head out on a two day fishing trip, I went through my normal pre-departure routine checking the oil, coolant, filters, and sea strainer. All of the levels were correct, filters were tight, and visually everything looked as it should. I started the generator and planned to let it run for a few minutes to let it warm up before switching from shore to ship’s power.

After a few minutes of getting things ready on deck, I returned to the engine room and was greeted by the strong smell of diesel. A quick glance at the generator and it was easy to see diesel pooling near the injectors.

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The Diagnosis

I immediately shut down the generator and cleaned up the fuel with some absorbent pads. Once everything was clean, I tried to determine where the fuel was coming from, but with the generator off, there was no active leak. After a few minutes of discussing the issue on the phone with Encore‘s lead mechanic (my father), I restarted the generator.

With some close observation during the next few minutes, I was able see the source of the leak. A one inch branch hose (non-pressurized) connecting the forward injector to the main fuel return line had developed a small hole.

The Repair

I did not have any spare 1/8″ hose onboard, so I removed the damaged one inch piece and gave it to my wife and father and law to see if they could match it with a new hose at the hardware store across the street. They pulled up to store at 4:01, and it of course closed at 4:00.

There was a small amount of play/excess in the main fuel line return hose. I knew that I could probably cut a piece out of it and use it for the branch hose that I needed. If it didn’t work, no big deal. We were still at the dock on shore power and we would just have to wait until the next day to purchase a new hose when the hardware store opened. With the goal of salvaging the fishing trip, I decided to cut out of the main hose the length that I needed. Luckily, it worked. The hose was still long enough to reach the fitting where I made the cut, albeit very snug now. The generator then ran for the next 40 hours with no leaks in the fuel return lines.

The Replacement

During the week following the fishing trip, the three branch hoses and the main fuel return hose were removed and replaced. 1/8″ rubber hose was used for the replacement. The nylon three way hose barbs, which are used to connect the hoses leading from the injectors to the main return line, were still in good condition and were reused.

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