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2012 JSW TDI
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Discussion Starter · #1 ·
Does anyone know the lift pump amperage? The plastic on the fuse to the lift pump was melted, but the fuse portion was not burned through or showing signs of being hot. Still, I had no voltage to the pump. I put a new fuse in and the pump started working again. I want to see what amperage the pump is pulling, and need to know what it should be, to determine if it's going bad or I need to look at something else in the circuit.
 

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I can't tell you of hand the current draw of the lift pump in the fuel tank.

Did the fuse blow?

Measure it with a multimeter.

When you turn the ignition on the fuel pump should prime for a couple of seconds.
 

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Discussion Starter · #3 · (Edited)
The fuse didn't blow, just showed signs of heat. The plastic was melted, but the metal fuse portion didn't show signs of heat. This tells me something is loading the system, just not enough to blow the fuse. I haven't measured the current draw yet. Wanted to get and idea of the value I should expect to see. I decided to change the fuse anyway and that reestablished power to the pump. In my opinion, the melted plastic with the fuse portion unblown and still intact should have still worked. Either way something is putting a load on the circuit that got the fuse hot without blowing it.
 

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Heat in an electrical circuit is caused by bad connection or resistance you need to check those out.

The fuse in an electrical circuit only protects the wiring and component. People fit a bigger fuse because it keeps on blowing bad idea it just takes a bit longer to blow.
 

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Back from the dead...

The fuse didn't blow, just showed signs of heat. The plastic was melted, but the metal fuse portion didn't show signs of heat. This tells me something is loading the system, just not enough to blow the fuse. I haven't measured the current draw yet. Wanted to get and idea of the value I should expect to see. I decided to change the fuse anyway and that reestablished power to the pump. In my opinion, the melted plastic with the fuse portion unblown and still intact should have still worked. Either way something is putting a load on the circuit that got the fuse hot without blowing it.
Did you identify the root cause?

I just had an identical failure on my car. I've replaced the fuse, but am worried that the issue will return. As a precaution I replaced the fuel filter and did not note any significant debris present in the filter media, so no reason to have caused excessive current draw. I do not know if the in-tank pump has a screen which could be clogged.
 

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Back from the dead, again...

I believe I may have found the root cause of my issue: the sunroof drains were blocked, allowing water to drip into the fuse panel. I have cut the drain nipple on all four drains of my panoramic sunroof, and water now drains as it should.
 
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