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Join Date: Sep 2003
Location: madrid, spain
Posts: 13
911 2.4 power failure

Hi I have a problem with my 911 2.4 S (1972).
Sometimes (more usually when engine is cold) is impossible to speed up. It´s occurs when I try to acelerate, RPM is like “enganged” in 1.500 line and do not go up. The car seems to be a power failure.
In this case, pressing the acelerator quickly several times, suddenly acelerate and all works “correctly”. I put “correctly” as the car over 2.000 RPM works, not correctly but not so bad: At least without power failure, but going up 5000 RPM has a a power failure again..
Acelerator linkage is ok. Distributor, rotor, sparking plugs & Ignition cables, are ok. Sparking plugs have 4.000 Km. MFI has been rebuilded a year ago.
Any suggestions to have this problem fixed?
Thx & rgds

Old 09-14-2007, 04:02 AM
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Join Date: May 2005
Location: Belgium/Europe
Posts: 137
Hello, I'm no expert, but it looks like a rotor problem to me.
Old 09-14-2007, 06:12 AM
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Location: Houston, TX
Posts: 895
when you say that the distributor is fine, do you mean that the shaft spins freely and distributes spark, or have you looked at the mechanical advance portion, as well?

if it was a fuel pump starvation problem, i think you would notice the knocking/pinging/popping as you would try to accelerate. since you didn't mention this...

it sounds like the timing is not advancing. if the centrifugal weights and associated springs are stuck, broken, missing, etc, you are most likely not getting the correct advance.

take off the distributor cap and gently turn the rotor by hand. it should be against the stop in one direction, and have spring tension against it in the advance direction. take the rotor off and look at the springs/weights underneath it. anything look amiss?

MFI guys will have to contribute if a similar situation occurs with the MFI pump...
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72 911T Targa - Sold

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Old 09-14-2007, 06:38 AM
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Location: madrid, spain
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Hi boys, thanks.
kucharskimb, you are right. One of the associated centrifugal spring is broken. That is the problem. But I´m afraid would not be easy to find another.
Thx & rgds
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Porsche 911 2.4S & 993 Targa
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Old 09-17-2007, 12:34 PM
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Two things, just buy a whole new rebuilt distributor if you can afford it. Second, How do you have a 5.0 liter in your Grand Cherokee? I have heard of 4.7, 5.2, 5.7, 5.9, and 6.1 liter V8's.
Old 09-17-2007, 01:57 PM
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This is a possibility. Not cheap but a possibility... I will check my budget for next year ;-).
You are right my cherokee has 5.2...It was a failure just fixed;-). A big machine in Morocco dessert.
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Porsche 911 2.4S & 993 Targa
Audi RS2, Ferrari 308
MB 220 Sb
Gran Cherokee V8 & Range Rover V8
Alfa Romeo Junior Zagato
Old 09-17-2007, 11:50 PM
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im having the same problem with my 2.4 could a valve adjustment and maybe some carburator tuning be in order also?
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Old 09-18-2007, 05:28 AM
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cycling has-been
 
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Join Date: Sep 2004
Location: Jersey Shore
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Is the hot air connection to the left heat exchanger in tact?
The MFI pump needs forced hot air when the motor is cold.
Bill K

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Old 09-18-2007, 06:34 AM
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