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-   -   Running on 4 cylinders. (http://forums.pelicanparts.com/porsche-911-technical-forum/474101-running-4-cylinders.html)

911Etarga 05-12-2009 12:45 PM

Running on 4 cylinders.
 
I have yet another problem with my '71 E.
I just fixed a leaking rocker shaft (you guys helped me out with that, big time!) After I set it down (it was jacked up on the passenger side for Cyl. #5 rocker) I started it up and went for a drive. The leak was fixed, but the power was really low.
Long story short, it is running on 4 cylinders. #2 and 3 are the culprits. I shot carb cleaner through the jets, jet holes, adjustment holes, etc(Zeniths). Checked for spark, they are getting spark. Changed plugs. Drove the snot out of it. Covered the intake stacks with my palm to suck fuel through.......no change.
What should I do next?
P.S. It has new wires, distributer, and everything else is re-built.
Random pic of my car....

http://forums.pelicanparts.com/uploa...1242160983.jpg

911mot 05-12-2009 01:02 PM

The only thing I can think of is #2 & #3 plug wires swapped

Zeke 05-12-2009 01:31 PM

It is so easy to get the wires out of order. I think we've all done it at one time or another. Go back, take your time.

jpnovak 05-12-2009 01:58 PM

I was thinking debris in the float bowls since #2 and 3 share the same carb segment. pull the carb top and have look. Also blow through the carb with 80-100 psi compressed air. Carb cleaner is often not enough to get rid of particulate matter.

911Etarga 05-12-2009 04:53 PM

Thanks guys,
I made sure the plug wires were on the right plugs, but I haven't pulled the top of the carb yet, but I will tomorrow and post results. With the car tilted to one side, maybe debris moved around, and into the fuel passages......?

timc 05-12-2009 07:27 PM

I used to run across the same thing with my old long hoods. Remove the carb tops, mixture screws, jets, spray carb cleaner, and blow with compressed air. Then get your trusty unisyn, take some time and readjust.

T77911S 05-14-2009 03:52 AM

i was thinking oil fouled plugs. try cleaning or new ones.

Peter T. 05-14-2009 04:56 AM

Shouldn't this topic be posted in the 912 Forum?

Sorry, couldn't resist!

911Etarga 05-14-2009 08:29 PM

Ha-ha.....I think I would take a well running 912 over this thing right now, it's killing me!

So, I just tor apart, cleaned, and blew out the carbs..........no change, it's still running on 4 cylinders!!!!
What should I do next?
Valve adjustment?
Scotch?
Grenade?

P.S. the plugs are good.

T77911S 05-15-2009 03:59 AM

plugs

ruf-porsche 05-15-2009 04:19 AM

Check your compression in theses cylinders.

911Etarga 05-15-2009 02:28 PM

More info,
It was running well until the last 2 weeks, then it started back firing a little bit when I started it up, but still ran O.K. Then it just started running like crap, on 4 cylinders. The thing is, the problem cylinders are on the left side(2&3) and when I put a hose up to the intakes to listen, #1 sounds like it isn't sparking or firing as loud as the right side(4,5,6). The plugs are not fouled, and it seems to run smoothly, but way under powered. There was, and still is no smoke.

Fishman7 05-16-2009 05:30 AM

I would tend to think you have something in the carbs, it may require taking them off and a rebuild, check fuel pressure, fuel filter, dwell, all of the basics. If it was running well before it should be something minor.

kidrock 05-16-2009 12:22 PM

I don't like to beat a dead horse, but it sure sounds like a plug/plug wire/dizzy issue to me. 1) Check those plugs for cracked insulation or something.
2) Make sure you're getting spark at the ends of those wires.
3) If items #1 and #2 check out fine, check cap for cracks and/or wear. Take a good look at the rotor, too.

Always do the easy checks first. If these checks turn out OK, I'd move on to the carbs. Hell, an easy check for the carbs is to spray into them and around the bases while it's running. If there is a significant change in the way it's running, then you've found yer problem.

Fishman7 05-24-2009 12:48 PM

Any updates?


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