Why does your fuel pump leak water?

Answer 1

My fuel pump leaks water because the fuel pump gasket is bad. The gasket itself is quite reasonable but the labor bill can be stupendous, depending on the make and model of vehicle. Especially newer models with sideways mounting, usually frontwheel drive are the most expensive as many parts have to be removed to get to the water pump. If the vehicle is not too old one can use black pepper to slow down or stop the leak and there are leak stoppers sold at your local fast parts store. Some times they work, sometimes they don't. First, we'll assume you mean an automotive fuel pump. Also, this question is not particularly applicable to modern electric pumps that are mounted inside the gas tank. We will assume that the question was asked about an old-fashioned, engine-mounted, mechanical pump.

Generally, these would never leak water. It is very likely that the fluid is coming from somewhere else, flowing down, and only appearing to be coming from the pump.

If the pump had a true leak, it would most likely spray out under pressure when the engine was cranking. A leak like this would be gasoline unless the car had somehow accumulated a lot of water in the gas tank.

A leak around the seal where the pump mounts would normally be oil. Cooling water channels are usually not too close to the pump mount.

So, more investigation is in order:

# First, identify the fluid. Is it really water, or oil, or gasoline, or a mixture?

# Is there water or gasoline in the engine's oil?

# Is the leak just a few drops? It could just be harmless condensate.

# Or does the leak stream or spray? Especially when the engine is cranking or running. Warning: If the fluid is gasoline, do not run the engine until the problem is fixed!