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Not starting, power to fuel pump issue


New member
27 Jun 2022
Hi everyone, I am new to the scene after recently purchasing my 1999 996.1 c4
I got to the car as a non runner. I was talking to a chap and I mentioned what was happening (wont run off the key but will if there is a live to the pump)
He pointed me in the direction of his forum and said to look into the ignition switch as these can be a common problem. Can anyone point me in the direction of a quality replacement? Also any thoughts on the matter? It's had a new pump fitted.

Many thanks,

If the car runs with a seperate 12 volt feed to the pump then the pump is ok .. your issue is with the feed supply to the pump ..

You have a fuse , a relay and some wiring .. Images below of the wiring , fuse and relay locations .

I kinda doubt an ignition switch issue as its not just the pump that would have no power but half of the sensors on the engine as they are all interlinked via splice points .. ie 1 feed wire is split into several feed wires for different items .

Check the fuse .. always a good start .. then pull the relay .. bridge term 30 with 87 .. does the car run .. yes .. the relay is at fault or the switch feeds to energise the relay are at fault .

If no then check there is a 12 volt supply at term 30 .. yes and there is a wiring issue from relay to the pump .

No and trace back the feed wire .

Workshop manual including wiring diagrams for your car can be downloaded from here ..


relay support 1 is above the fuse box .. pay careful attention to the numbers on it and make sure you get the correct relay .. easy to get the wrong one .


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Thanks deMort, i will look into this when i get a day back on the car.
thanks again :thumb:

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