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Porsche 911

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jackq

jackq

Jedi Knight
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Besides my MGs..I have two Porsche 911s. One is a 70 E model with triple Webers..that ones okay. The other is a 75S..has fuel injection. Strange thing is, a while back I noticed a high pitched squeal..followed by gas dripping from the exhaust port under the engine and of course six fouled plugs?? Dried it out, new plugs..good to go..for a while. Did it maybe three times. Now it screams when you turn the key and gas literally shoots out of the engine. Changed the fuel dist..should have used the money for a vaction for all the good it did.If you pull all six injectors and turn the key..not crank, just turn the key till the ign. is on and all six injectors shoot gas across the room. All six injectors are supposed to be on all the time, thats normal on this system, but the amount of gas is tremendous. Anyone out there have a Porsche, or heard of this problem?? Have been to numerous Porsche sites but I think most of these guys just own them...maybe can open the engine compartments(with help) Thx.
 
Don't know much about them, Jack...but if you'd like, I'll come take it off your hands so you don't have the worry (what with a new MGB & redoing the MGC)! hehehehe
 
Had a 67 with dual webbers, there were no triples. Sorry can't help. Sold it because it was an expensive PITA.
 
Jack, You said distributor, and by the year this is a CIS car, yes? The center "pin" in the fuel head should regulate the pressure to the injectors. The round "swashplate" under the intake boot may be crudded up on the underside and can cause what you describe, too. I would assume you've cleaned all that tho. The alignment of that plate (centering) is CRITICAL, as the clearance is in thousandths of an inch, and if it "hangs" the fuel head is sending pressure to the injectors. With the plate/arm at rest (the "zero" position, engine off) there should be no pressure thru the center valve on the head. When you lift the plate you should hear that "tea-kettle" scream... kinda like a lobster being tossed into the pot. Gimme more detail and we can work thru this. The system is kinda neat, IMO. Simple.
 
In answer to GB1....these are trible barrels on the 70E model. Had Zeniths, upgraded to Webers..Overhaul kits have six of everything, a Porsche spped shop said its like buying six seperate carbs...kinda just hooked together. I've tried everything on the fuel dist. even manually pressed the throttle plate to the totally rest position..screams like a banshee. Every day that I walk into my shop and see it I want to hang a sign on it"A dollar a hit with a hammer" Its a shame as its a beautiful car. At the moment, I'm having a blast putting around in the (new) B. Wife loves it, went to dinner in it last nite. Yesterday I drove the C, handles well at 90...didn't even use overdrive.
 
I had a '70 911T -- my impression was that in 1970 only the T had carbs from the factory, and the E and S had injection. (This is the sound of Sam going to his books to check, because his memory ain't as good as he'd like...)
Yup, books confirm that the '70 911E was indeed originally fuel injected.

Many people ripped the FI units off for the T's carbs -- especially racers. In '70 the Ts had Zeniths (they had Webers previously.)

Very fun cars -- although I've never liked the gearshift in early cars. It's like a secret handshake to get into 2nd rather than 4th!
 
sammyb wrote: [ QUOTE ]
Very fun cars -- although I've never liked the gearshift in early cars. It's like a secret handshake to get into 2nd rather than 4th!

[/ QUOTE ]

heh, very true about the shift linkage. New bushes and bobbins help some, but it's still vague if you're used to something like an Elan.
 
It was changed from F/I to carbs many years before I got it. I worked on the thing most of yesterday and the day before. I've about decided this car is destined to become alot of parts for sale, Im sure I can get more for it in parts than as a complete non-runner.
 
Too bad Jack,

In one of my books by Scott Fragher - Porsche the Utimate Guide (2005 publication I think) there's a price guide scale based on vehicle condition 1 (Excellent) through 6 (Parts Car).

According to the price guide a 1970 911E a 6 "parts car" (running or not) would bring about ~$1010. While a "restorable" 5 level car might bring $3100+.

So you're right it's probably worth more parting it out if you really don't want to deal with it anymore.

Good luck,
 
This is frustrating. CIS is usually as reliable as a house-brick. Gotta be a checkvalve malfunctioning or the center pin sticking. Have you checked system pressure?
 
I popped the fuel dist. and the center pin slides free and easy. All the books I have say"take it to a certified mechanic blah...blah...nowhere can I find a fuel pressure...or anything about check valves or fuel regulators. As soon as you turn the key...not to start..just to ignition...the thing screams. I know I'm missing something and its probaly simple. I just saw a 911 idenical to mine except mine is nicer. Its selling for 11k. I love my and my CGT...but **** this 911 is a blast to drive.
 
Does it have a vane type flow air meter? It may be binding and not closed all the way. On my 80's bosch injected alfa (and also on my toyota which is a japanese copy of the bosch), the fuel pump will only come on with the key in ON, and the vane open a bit by the engine pulling in air(theres a microswitch in there to turn it off if the vane is closed all the way). Might be a place to check anyway. If it has one, wouldn't hurt to clean the inside of it anyway, and make sure it opens and closes correctly.
 
This is a CIS car, Kenny. EFI is what you are thinking of.

The pumps run at ignition position for (IIRC) a few seconds to build delivery pressure. The system pressure should be about 32~38 PSI. What is not sent thru the fuel head to the cylinders should be recirculated back to the tank. The "screaming" shouldn't start unless/until the vacuum demand raises the plate. I'll dig around and try to find my CIS training manuals this weekend. Are you sure the throttle plate is centered and not "hung" at an edge? It sounds like there is something holding it in the "open" position.

They ARE a fun car to drive.
 
No problem, I thought I'd throw my little bit of knowledge around and see if it helped. /ubbthreads/images/graemlins/thumbsup.gif
 
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