Alivreal

A little help and advise please.
83 SC, the fuel pump runs when the key is put in the ignition and set on the first turn before the startup. If I forget to go direct to startup I flood the engine which I have done a couple of times. Any reason why this would have been done to this car by the previous owner? Any way of reversing to stock? Or shall I leave it as it is.

Alivreal

any ideas guys?

Mark Salvetti

I'll take a shot with some ideas.

The fuel pump shouldn't run with the ignition in the On position. You can make it run for testing by pulling the red relay and putting a jumper between terminals 87 and 30a. So I would take a look at the wiring at your fuel pump relay to make sure a previous owner hasn't messed with it.

There is also a safety switch behind the air box. If this switch is disconnected, the fuel pump will also run. I couldn't quickly find a thread here on Rennlist with a photo, but there is a good photo of the switch and the location here:
http://forums.pelicanparts.com/porsc...ml#post6718582

But I don't think either of these are your problem, because you mentioned the engine flooding. Normally if you jumper the fuel pump, the fuel just circulates back and forth between the fuel tank and the fuel distributor, and does not feed the injectors. However, I'm wondering if you might have a problem with the CIS throttle plate (visible in the air box behind the air filter). The throttle plate is connected to the fuel control plunger in the fuel distributor. If this is not seated properly, it could allow the pump to run and allow fuel to get to the injectors.

Here is a link to the Bosch CIS manual. I think you should also be able to search for throttle plate inspection and adjustment threads.
http://members.rennlist.org/vilhuer/...p%20Manual.pdf

Hope this helps. I'm sure someone with more experience than me will chime in soon.

Mark

Alivreal

Thank you so much Mark. I will give this a go. If anyone else has any ideas it will be greatly appreciated. The issue is intermittent so unsure if it's me on start up making the fuel pump run for a longer time before cranking or if there is another problem altogether when I have a no start issue.

rc 82nd

Thanks Mark!

Mark Salvetti

What part of the problem is intermittent? Does the fuel pump always run when the key is in the On position, and only the flooding is intermittent? Or does the fuel pump only sometimes run when the key is On?

If the car is off, the fuel pump is only supposed to run when you turn the key to Start. That bypasses the safety switch. After the engine starts, the throttle plate lifts (due to air flow). This also overrides the safety switch and allows the pump to keep running even with the key in the On position. If the engine stalls, the throttle plate drops, triggering the safety switch and turning off the fuel pump. At least that's how it is all supposed to work.

Mark

Alivreal

The intermittent problem is the non starting which I am assuming is caused by the flooding as the fuel pump is on when the key is in position 1 rather than cranking. The fuel pump is always running at position 1 and thats not the intermittent issue. Thank you for all your help. Any more ideas would be greatly appreciated.

Mark Salvetti

Ah, I understand. So you really have two problems. The first is the fuel pump is running when it is not supposed to, and the second is an occasional non-start.

They could be two totally separate and unrelated issues. Start with getting the pump to run only when it is supposed to, then see where that leaves you.

Mark

Alivreal

Thank you Mark. We will tackle in the order you have suggested.