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vwnewton, VW Owner,ASE Master and L1 Advanced
Category: VW
Satisfied Customers: 660
Experience:  25 years of VW obsession turned into a job, last 15 years as a VW Tech.
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2003 Jetta: replaced relay..key turned on, but still no start

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No start 2003 Jetta, 1.8T;no juice at pump- check fuse, ok; replaced relay. Now we get an instasnt flash at pump when key turned on, but still no start.
Hello, Jason here to help.
Do you hear or feel the pump run when the car is cranked, or the key cycled?
If not, try this : BE CAREFUL in any auto repair!
Set the park brake, place in park or neutral with manual. Have someone apply the brake and try to start the car with you tapping the passengers side bottom of the fuel tank with a chunk of wood. This will jar the fuel pump in the tank, freeing the stuck brushes. This is a common problem.
If the car starts then the pump is failing. This is caused by running the fuel tank lower than a 1/4 tank. The fuel pump uses fuel for cooling, it is submerged in fuel inside the tank...
Let me know if it started. Jason
vwnewton and 2 other VW Specialists are ready to help you
Ok, smacking the tank didn't help. At the Blue/Red wire at the tank, is there 12v when cranking the car?
Did this just happen overnight, or did it die while driving?
Please hit reply, Jason
Customer: replied 7 years ago.
Tried thumping the tank b4 with no success.
If there is just the quick flash of power when turning on the key, but none when turning the car over on the blue/red wire at the pump, there are other possible causes.
Remove the oil cap and see if you can see the camshaft spin when cranking, or remove the upper timing cover to see the cam belt turn. Timing belts can shed teeth and cause the engine to go out of time. The cam sensor is used by the computer to command the pump on. The quick flash is a prime pulse to prime the fuel system for starting.

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