The Saga of the Port Engine

Those of you who are interested in engine problems and diagnosis have been trying to figure out what is going on with our engine, just as we have. I finally have time to write a blog and thought that it would be interesting to recap what we've learned.

Everything was fine with both engines until May 30, 2012, at 0900, where the log entry says "Port engine now having fuel filter replacement surgery." This was on our leg from Turks & Caicos to Georgetown. Georgiana says that Tom and Linda must have poisoned the engine because they had to leave. Maybe they hid the missing Bimbos in the tank.

When LUX was in charter, the fuel tanks probably never held less than 3/4 of a full tank. Even a week of motoring in the BVIs would result in only using about 1/4 tank of fuel and the tanks would be topped off after each charter. But with our long segments, we ran them down to 1/4 of a tank (using 3/4).

On the T&C to Georgetown segment, the port engine started to periodically lose RPM. When run at 2200 RPM, it would slow to 500-1000 RPM for about 5-10 seconds, then speed back up to 2200. It would repeat this cycle every 20-30 seconds. If we set the throttle at 1800 RPM, it would run fine. We had not taken on any fuel at the Turks & Caicos marina, so bad fuel couldn't have been the problem. And we didn't think that we would have run through 3/4 of a tank of fuel without any problems, then start experiencing problems, particularly since the passage wasn't totally smooth and the fuel tank should have been mixed up from the boat motion.

Experiment 1: Replace the primary fuel filter. The engines have two fuel filters, a Racor primary filter and a Volvo spin-on engine filter. The primary filter is typically either 30 or 10 micron while the engine filter is 2 micron. I had included four Racor 10 micron filters and two engine filters in our engine spares. Since the problem looked like fuel starvation, we decided to change the filters, starting with the Racor. The old filter looked fine. We pulled fuel from the bottom of the tank to top off the Racor filter canister and the fuel looked fine. The Racor canister had a lot of air in it, so maybe it was a gasket leak. No such luck. It initially sounded like it was fixed, but a few minutes later, it started the same symptoms.

Experiment 2: Replace the secondary filter. Next, we replaced the secondary filter - the 2 micron filter. Our luck changed for the worse, and the engine would not run even at 1800 RPM. We had to throttle back to about 1500 for it to run smoothly.

At this time, all sorts of speculation starts about the possible cause of the problem and potential solutions. Fuel pump? Fuel? Something blocking the fuel line?

To Be Continued…