Troubleshooters...help! '74 ignition switch blues.

[bigchillcar]

Hey gang,

Here's the problem:

For the last week or two my car has been troublesome at times on start-up. The ignition switch has 4 positions if you include 'cranking'. Position '0' is 'off', so that leaves the other two. In the first of those, kind of like 'accessory' I suppose, I get power as appropriate. The next position (Porsche calls it '2' in the manual) is when I hear the fuel pump, etc. If I don't hear this, it won't start and this position has been intermittent. Yesterday it was dead in this position until I put my hand behind the switch and fumbled around a little, the pump noise came on and it started. This morning, nothing happened in this position for more than 5 seconds and then I heard the pump come on and it started...there should not be this delay of course.

So what should I be looking for exactly? Should I expect to see a loose wire maybe when I have time later to get a good look or is this an indication that it's simply time for a replacement?

Regards,

Ryan

1974 911 2.7 CIS coupe w/sunroof

[Brian Olsen]

Ryan,
The ignition switch has two parts; the tumbler, and the electronic portion behind the tumbler. It is not uncommon for the tumbler to wear to the point where it will not rotate all the way the the furthest position that will engage the starter. It doesn't sound like this is the problem in your case, though. The contacts on the electronic portion can also become worn to the point where they no longer make contact. You can try replacing the electronic portion of the starter. It's not an expensive part (by Porsche standards), but it is a PITA to get to. Another possibility in your case might be intermittent wiring to the fuel pump. I'm not familiar with the wiring for a '74, so I can't provide any specifics.

Regards.

Brian Olsen

[bigchillcar]

Brian,

Terrific! Thanks for the good leads. I agree with your assesment about the tumbler probably not being the culprit. The electrical portion's contacts were my suspicion as well. It shouldn't be too difficult a problem for me to determine the intermittent wiring to the fuel pump possibility. Of course, when I don't hear the fuel pump in position '2', continuing to try to crank doesn't hear the starter engaging either. Does not getting power in pos. 2 preclude being able to at least turn the starter? Thanks!

Ryan

1974 911 2.7 CIS coupe