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dweymer's Avatar
 
Join Date: Nov 2004
Location: Tucson, AZ
Posts: 2,355
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CIS fuel injector??

1974 911, freshly rebuilt 2.7 ran fine but had an oil leak.
Re-used the old injectors.
I removed CIS to get to the oil pressure switch and thermostat.
tightened them and put CIS back on.
Now it wont run without playing with the throttle, and it seems as though it is starving. It runs like it is on 3 cylinders.
When I back off throttle it will run fine for a second then it runs like it is on 3 cylinders.

Plenty of fuel pumping into the fuel dizzy.

How much fuel should the injectors put out over a specific time period?

I am thinking some crud got dislodged in the fuel dizzy, put am trying the injectors first, they are easier.

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Donnie

Currently Porsche-less.....
Old 11-25-2006, 11:06 AM
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LakeCleElum's Avatar
 
Join Date: May 2004
Location: Lake Cle Elum - Eastern WA.
Posts: 8,417
Pull your injectors, aim them into a glass jar you can see into and raise the senor plate. The should spray a wide, fine mist pattern. If they dribble or shoot straight fuel, it will run the way you describe...If the injector is suspect, there are compaines that clean them..
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Bob S.
73.5 911T
1969 911T Coo' pay (one owner)
1960 Mercedes 190SL
1962 XKE Roadster (sold) - 13 motorcycles
Old 11-25-2006, 12:41 PM
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pulled 4&5 both are good. Then stopped to re-evaluate my troubleshooting.

I did a pressure test: not sure on the terms so feel free to correct:

Setup:
cold engine, gauge hooked up between WUR and fuel dizzy, valve on WUR side.

Turn on fuel pump no electric to WUR, closed valve(system pressure?): 4.75 bar, 69psi

Open valve(control pressure?): 4.75 bar, 69psi

Plug in connector: no change

I manually moved the airsensor plate and can feel the piston move and do get fuel out of at least 2 injectors.

Did not fire the car, my kids are sleeping and I would like it to stay that way!
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Donnie

Currently Porsche-less.....
Old 11-25-2006, 03:37 PM
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Join Date: Nov 2004
Location: Tucson, AZ
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More weirdness:
I found that I have no supply line from fuel dizzy to throttle position pressure regulator (never did, and the car ran, just more strangeness) EDIT: I just figured it out reading Jim Williams' page, I have a 76 CIS system on my 74 engine.


no voltage to WUR with ignition on, checked terminals on wur with buzzer, got signal. The wires here have also been "changed"

What a mess, I try to fix some leaks and my Sunday drive is shot!
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Donnie

Currently Porsche-less.....

Last edited by dweymer; 11-25-2006 at 05:06 PM..
Old 11-25-2006, 05:01 PM
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Join Date: Oct 2006
Location: MYR S.C.
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u may have connected the vacuum to the WUR to the wrong place.
check for power to the WUR
put a vacuum pump on the WUR, see if it will idle with vacuum applied

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Old 11-27-2006, 03:35 AM
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