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spuggy spuggy is offline
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Join Date: Jul 2003
Location: Glorious Pac NW
Posts: 3,477
Originally Posted by Alan L View Post
I have pulled mine completely apart. But be careful, from memory there are a bunch of springs and tricky bits in there. Nothing fatal, but take care when you open it to see how things go back. I spent a looong time reassembling it.
Oooh. Now you've got me thinking... I frickin' hate the start interlock on the later electrical switches (with the 964 part #). But the older 911 part without the interlock is NLA (and was double the price for years before that).

I wonder it's possible to just remove the interlock from the electrical switch? (Some people say their interlock is in the locking portion, but on all 3 of mine, it's only in the electrical part);

Originally Posted by Alan L View Post
but I don't think your pumps should run until the engine does. I suspect you have another problem lurking.
Ditto. Mine always did, but it was a transplant. Even when the plug on the back of the air sensor plate was hooked up, my pumps still ran with the ignition "on" - but it shouldn't have done; apparently some mismatch between the motor harness/car wiring.

You should probably check that the air sensor plug and the CSV plug are both plugged in and not swapped by mistake; they're in the same place and almost identical plugs (from memory, the air sensor plug is more blue-ish, and the CSV valve more green-ish). The car will likely start just fine with the wires swapped - e.g. without the CSV - because the TTV only kicks in at some very low temp. It's pretty common for the air sensor plate to be disconnected for diag or not replaced, for some reason. This is what stops the pumps from running until the motor is started (and the plate pulls off the stop). Assuming that everything is connected/working correctly...

That your pumps sometimes run and sometimes don't would worry me - enough to look into it, anyway. I had a Honda 750 that sometimes wouldn't switch on but mostly did; I pretty much just ignored the problem until the wiring harness released the magic smoke one day..

There's a bunch of other things it could be - but one possibility is that some contacts inside the switch may be worn/arced down inside, or the mechanism could be worn/flopping about and doing things it shouldn't. Yeh - that could be bad...

As Ollie says, the electrical portion can be replaced without touching the lock barrel, but it's a pig to get at the top screw... #1 the most awkward/frustrating job I've ever done on a 911 - and I've done it several times now. Replacing the hood shocks and adjusting the flappy air cables in the frunk - even the one behind the brake booster - pale by comparison...

If needed, bendy screwdriver or a very small ratchet is the hot tip. Once started, you'll probably do most of it with fingertips on the screwdriver bit anyway...
'77 S with '78 930 power and a few other things.
Old 04-22-2018, 12:42 PM
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