B777 Captain reported a fuel leak and resistance from maintenance personnel when he requested they look into the leak and internal engine puddling. Local maintenance was overridden by System Maintenance controller due to fuel puddling in the engine and removed the aircraft from service.

Narrative

During my exterior walk around I smelled raw fuel as I approached the number one engine. Upon a visual inspection of the interior of the engine from the rear I noticed a large amount of puddling fluid just behind the fixed stator blades. I also noticed a very strong raw fuel odor. I wrote up the leak. Maintenance finally came to the cockpit and said it was signed off and the drips from the bottom of the engine were within limits. I was confused at that point because that wasn't what I wrote up and mentioned that to the mechanic. I also showed him photos. He said he didn't notice the fuel in the engine and would go look. A bit later he returned and said he didn't see any leak and the puddling was gone. I asked where the puddling went. I think his response was we wiped it up. In any case I told him with fuel dripping from the bottom of the engine and puddling internally I wanted to know the source. He said he didn't know the source and it was signed off and that's all he was going to do. I told him I wanted the source located. He said okay and left. Then a maintenance manager" came and said "so what's the issue here? The plane is signed off and good to go" I said there's no issue; I repeated what I told the previous mechanic. His answer was the same. There's no leak and you're good to go. I disagreed and said I wanted the source identified. He again said I don't know what the issue is here; it's signed off. I told him I want the leak sourced. He responded with there's no leak. I asked then where's all the drips and puddling coming from. His response "I don't know but it's signed off and you're good to go". I repeated my desire to source what I know is a leak. He again said there's no leak and he wasn't going to investigate further unless I refused the plane. I said okay and refused it. The ACARS refusal code per the FOM was rejected so I phoned Dispatch and had them accomplish the refusal. They also got maintenance control on the phone. I explained the issue to him and he readily agreed with me. He said "they can't sign that off with an active fuel leak inside the engine". I told him they did and he said he'd look into it. In the meantime we accomplished a five minute engine run after coordinating with the Chief Pilot. I was at the engine after the run when they opened it up. It again had a very strong raw fuel odor. Once open it was quickly apparent that the same area was this time soaked in raw fuel. The plane was removed from service for repair. This is the third time I've had engine fluid leaks in ZZZ and had to push quite hard for the needed repair. Each time when the leak was sourced the aircraft were removed from service. The maintenance manager was polite but quite forceful in his attempt to get me to take the aircraft. My First Officer (F/O) commented as such and also said a lot of Captains would've given in under that pressure.My concern is two fold. One; there should be absolutely no pressure from maintenance to take an airplane a Captain questions a maintenance issue on especially an unairworthy one such as my three in ZZZ. Two; as this is my third occurrence for the same type of write up at the same location it goes beyond coincidence and I believe is a systematic problem in ZZZ. I believe; at least in my three occurrences; ZZZ maintenance was reluctant to pursue known engine problems until added polite verbal pushing from me was applied to get them to accomplish the inspections. I'm very concerned that this is a systemic problem there and needs to be addressed by the appropriate higher level management; regulatory and safety individuals."