Perky's Perplexity Part 2

Greetings all!  We just got back to La Paz this morning following a 5 day tour of the Sinaloa region of Mexico – including the Copper Canyon of the Sierra Madre.  Stay tuned for April’s post on that wonderful trip!

Many of you have left some very insightful comments and questions concerning Perky’s health condition.  And most of your thoughts are right along ours – which at least gives us some consolation that we’re not simply crazy!

Let me first give you a current update….

As Dave Steffens posted in the comments section, we decided to give our fuel supply a closer inspection.  To rule out a constriction in the fuel supply side (i.e. tank, fuel line, Racor 500FG filter or lift pump), we hooked up a temporary fuel supply using a 5 gallon Jerry Can of San Diego’s finest diesel, new fuel line hose, and an electric fuel pump we had purchased back in San Diego.  We then connected the Jerry can/fuel pump hose directly to the inlet on the engine mounted lift pump – just upstream of the engine-mounted secondary fuel filter.  If Perky’s power problem was coming from the fuel supply side, this temporary system should give us a boost in power.   As usual, Perky started without difficulty, but the problem of poor power under load remained the same.  Satisfied that the fuel supply (at least up to the high-pressure injector pump) was adequate, we reconnected the tanks and hoses. 

To clarify my prior post regarding the to the Racor Filter, the vacuum gauge mounted just after the filter reads a negative (i.e. suction) pressure of 0 to -5 inches mercury.  Other than one instance (when it read as high at -17”Hg vacuum) it has always been in the 0 to -5” Hg range.  Yes, the high suction reading did take place during the problem period, but I haven’t seen a reading like that since. 

With regards to the engine load, here are a few other details of note:

1. Propeller
1. Max Prop, 17” diameter, three-bladed, right-handed, feathering prop.
2. Current pitch setting – unknown, but hasn’t been adjusted since original installation.  Upon visual inspection, blades feather easily and prop turns easily both in neutral and in fwd gear.  All three blades appear to be set at same pitch with no discernible damage.
2. Transmission
1. Hurth HBW 150, new in 1999.
2. Ratio 1.88:1
3. Fwd/neutral/reverse
3. Shaft
1. Dripless rotary seal
2. Turns easily by hand in neutral/forward and reverse

Tom Davison asked some important questions as well regarding the history of the present illness (HPI).  Couldn’t help from throwing in a good medical term.  The previous max RPM before the onset of the problem was never purposely tested, but we certainly had no problem reaching engine speeds of 2500 RPM.  We usually ran the engine at 1800-2000 RPM to maintain a boat speed of 6-7 kts and fuel consumption of 1 – 1.2 gallons per hour.

With regards to engine exhaust, when we do the dock-side power test (aft spring line holding the boat stationary and transmission engaged in forward) the smoke output does increase, but it’s never black (only grayish).   From what I’ve read from Nigel Calder’s book on diesel engines, black smoke means unburnt fuel, blue smoke means burning oil, and white smoke means water in the engine.  But what does gray smoke mean?

I’ve uploaded a short video with this post, which shows the color and amount of exhaust both in neutral and in gear to give you an idea of what I’ve been trying to describe.

At this point, I’m still thinking that the Perky is starving for fuel.  There doesn’t seem to be any indication that we’ve overloaded her or that anything has changed with regards to the drive train (transmission, shaft or prop).   Nor does there seem to be a problem with compression or blow-by because the engine always starts promptly and sounds great.

Next proposed steps:

1. Disconnect rigid fuel supply tubing from secondary filter to fuel injection pump.  Flush with diesel both forward and backward to ensure that no restriction is present up to the injection pump.
2. Consider having fuel pressure measured at the connection to the injector nozzles to verify a properly functioning injection pump.
3. ?

We'd also like to thank Rob from China Doll (Passport 51') in La Paz who paid us a visit last week, looked over the engine and gave us his thoughts, which were very helpful.  Then, he even gave us a ride to the ferry, where we embarked on our journey to the Copper Canyon.  What a community!

Thanks again for your thoughtful comments, and continue posting because the T-shirt is still up for grabs! 

Peace and Happiness,

John