Well today I cleaned up a few connections. Tried to source some original porsche fuse box screws without any luck, wrecker said they would only let any go if they had a damaged fuse box. Hmmmmm... sourcing parts in Australia is a pain. There is definitely more that I can do further down the track but what I did today did not hurt.
While playing around with my friend tonight, we noticed a bleedingly obvious lack of power to the fuel pump during cranking. I've had starting problems that have necessitated 'priming' the k-jet virtually every time I drive it and I suspected the fuel pump wasn't working during cranking, but never knew a good way to investigate it as I found this car honestly a bit daunting.
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Originally Posted by E Sully
Look for a Red/Green wire on the fuse panel in the front trunk of the car, this is the feed to the pump in the rear. Normaly if is connected to the unprotected side of the fuse, and the fuse does not protect it. The power is normaly from a Red/Black wire under the same terminal that comes from the ignition switch.
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Yep, the red-green wire does the fuel pump. If I disconnect it with the fuel pump running, the fuel pump shuts off. If I give it 12V at any time, it starts up. But if I REMOVE the fuse, the fuel pump will continue running. Is the power coming from behind that terminal of the fuse box?
Quote:
Originally Posted by ossiblue
Your 75S does not have a fuel pump relay
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Awesome, thankyou.
Quote:
Originally Posted by ossiblue
that's why it comes on with the ignition switch although it should not start until the switch is "on", not "accessory" as you have pointed out. IIRC, the pump is powered from fuse #7 in the upper fuse block in the front of the car. If you look closely, you should see the red/green striped wired going to the fuse.
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The
red-green wire is there, but it goes into what I would call #6. It gets power during 'Acc' and 'On'
A
red-black wire is in the same position of what I would call #7. It gets power during 'On' and 'Start', which is when my fuel pump
should be getting power, but is not. It is either getting nothing or suffering a huge voltage drop during cranking. This red-black wire seems to go to the ignition system.
Just to clarify:
If you put 12V from the battery onto the red-green wire, the fuel pump runs. If you remove the wire from the fusebox with the fuel pump on (Acc on or Ign on), the fuel pump stops. But when you remove the fuse from the fusebox, the pump keeps going! So it definitely is not receiving its power from the fuse, there is another connection behind the fuse box into that terminal I imagine?