Thursday, September 17, 2009

An update!

So while Stephanie was writing and uploading her post below, she was ignoring her phone that was telling her I'd called and left a message.

Note to self: Don't leave phone on silent mode in different room.

If she'd picked up my message, her post may have been a little different.

Yesterday, Neil performed a test on the injectors, that deliver fuel into each cylinder. Unlike gas engines, diesel engines do not burn all the fuel they take from the tank and some fuel is returned back to the tank. The test involved measuring how much fuel was being returned from each injector. He has this nifty little rig that has a hose connected each injector to a small measuring cup. You can then measure how much fuel is being returned by each injector. This should be a certain amount at idle and a differing amount, either too low or too high, indicates various injector issues.

We turned the engine on and watched the fuel slowly creep it's way up the hoses to the measuring cups. All, that is, except on the injector furthest aft. In it's hose, the fuel was barely moving, indicating that the injector wasn't taking any fuel at all. The problem was obvious and a new injector called for. When Neil pulled the injector it's tip was dry. As it should have been wet, it was definitely malfunctioning. A few calls later and a replacement was found in Michigan and overnighted.

By the time I had arrived at the boat this morning, Neil had replaced the injector and had both engines running. Fuel consumption on the port engine was now slightly lower than the starboard, rather than 20% higher. A good sign! There was no vibration in neutral, so we went out into the river to check with the drives engaged. No vibration with the drives engaged, either! So things are looking really good!

Neil advised going out on a full sea trial today. There were still a few things needing attention. The fuel delivery tubes needed to be replaced and they'd sent the wrong type. These steel tubes connect the common rail, a cylinder containing diesel fuel pressurized to some ridiculously high amount - 36,000psi or so - to the injectors and should be replaced whenever changing any injectors. Having the fittings blow at speed would be really bad. Neil also noticed that the priming cap above the secondary fuel filter wasn't priming. This could cause air to leak into the fuel line which could also cause performance issues.

So we'll do the full trial tomorrow. I'll post up when we're done, but it's looking really good!

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