4100SCR fuel leaking -Tanks Pressure tested OK

[georges]

One Friday I half filled the tanks for the 1st time in months. On Wednesday there's a fuel odor in the bilge and an apparent leak. We vacuum out the bilge and I call a remediation service (RS) for the spilled fuel. Six hours later when the RS shows up there's more fuel in bilge. My mechanic notices an improperly seated injector with signs of fuel leaking. The engines have not been started since Friday so we agree that it is doubtful that it was the injector because we don't see how the fuel could defy gravity to get to the injector through the supply panel and fuel filters. We're certain it's the tanks and the RS vacuums the tanks dry. I have the expert in Miami to come out and pressure test the tanks. He puts in 3+ PSI and the tanks and lines to the supply panel hold. I'm relieved it's not the tanks. But we're baffled how it could be leaking with all engines (and fuel pumps) off.

The initial fuel was about 15 gallons, then about 3-4 gallons 6 hours later.

BTW the insurance covered everything without deductible including the diagnosis of the leak, but not the repair.

[mmwjr]

georges first welcome to the site.

For this size boat I am assuming these are not gas engines.

How long did they leave the tank pressirized for? Should have been several hours to overnight.
Did they inspect the fill hose/s?
Is there a tranfer hose between the tanks?
I find it hard to believe that the engine fuel system would hold that much fuel to leak .

May be time to just replace all the hoses.

[georges]

Mike

These are 330 Cummins. From the tanks all the fuel feeds to a panel which controls shut off and supply and return to/from port/stbd tanks, it's a 3 by 3 panel of levers for each engine and the genset. Form the panel fuel goes to the Racor fuel filters and then the engines. The "expert" was satisfied with a 1 hour test of pressure. The fill cap on one side wasn't flush, the other was. We switched caps on the test so that there would be no leak through the caps. Since the caps were pressurized this test would have included the fill hoses. He sealed the screws in the senders with teflon tape to get a good seal. The senders were removed to vacuum the fuel. That is the fuel was not sucked out like the waste tank as that might have collapsed the aluminum tanks.

The "expert" closed the levers to the engines putting them in a shut off position. He said not being a mechanic, he didn't want to send the pressure beyond the panel.

All the fuel transfer would go through this panel.

Thanks for welcoming me. I was here years ago and just could not find my old login info.

It's quite a mystery. We're taking the boat to a yard this week for more tests. I'm trying to get some thoughts from the forum as what the cause could be.

[mmwjr]

I will yield to your mechanics knowledge as these big boats are beyond my experience.

Hope it works out and let us know the final solution as there a few others here with this model.

[Phillbo]

Any leak putting 15 gallons of fuel in to the bilge should be obvious.