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69 Charger wanting to slowly cut off

Started by JRH LEE3, May 14, 2016, 04:39:20 PM

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JRH LEE3

May 14, 2016, 04:39:20 PM
Any idea's on when my 69 Charger 440 is running in idle it runs great.  When i'm driving it runs great.  When I stop at lights or general stops the motor wants to slowly cut off, but if I put it in netural or park it picks back up idle and runs great????????????

Please HELP!!!

myk

#1
May 14, 2016, 04:41:02 PM
What's your idle speed set at?

crj1968

#2
May 14, 2016, 04:47:07 PM
Power brakes?  (vacuum leak)

JRH LEE3

#3
May 14, 2016, 06:29:13 PM
yes, it has power brakes.  I have no idea what my idle speed is set to???  I have always just fine tuned it to ear.......

Does it sound like it could be a vapor lock or NO ??

daveco

#4
May 14, 2016, 06:40:39 PM
It could be a vapor lock issue, I'd also check fuel pressure at hot idle.
R/Tree

JRH LEE3

#5
May 14, 2016, 08:37:50 PM
How does one check fuel pressure and what is a normal reading??

Patronus

#6
May 14, 2016, 10:30:37 PM
My thoughts were fuel related as well. Do you have metal or rubber fuel line in the engine compartment? It it run down along the manifold by chance?
'73 Cuda 340 5spd RMS
'69 Charger 383 "Luci"
'08 CRF 450r
'12.5 450SX FE

crj1968

#7
May 14, 2016, 11:19:49 PM
Why would a fuel issue only affect the car in gear?   

Check your plug wires.  I had -chug-chug-chug issue at stops today and found my #8 plug wire came off the plug.
Same symptom as yours...running on 7 cyls sounded fine in park or neutral and while moving.


daveco

#8
May 14, 2016, 11:31:19 PM
 Actually not so much fuel pressure, but rather fuel volume. If the fuel pump is weak or has a leaky valve it may have poor delivery at a very low idle (when idling in gear). Just raising the rpm a few hundred is enough to compensate.
Since it's not practical to measure fuel delivery volume on a hot idling engine we extrapolate from fuel pressure. The fact that it is a gradual repeatable decline and recovers with an rpm increase leads one to suspect a fuel problem.

Could also be ignition.
R/Tree

crj1968

#9
May 15, 2016, 01:21:01 AM
Quote from: daveco on May 14, 2016, 11:31:19 PM
Actually not so much fuel pressure, but rather fuel volume. If the fuel pump is weak or has a leaky valve it may have poor delivery at a very low idle (when idling in gear). Just raising the rpm a few hundred is enough to compensate.
Since it's not practical to measure fuel delivery volume on a hot idling engine we extrapolate from fuel pressure. The fact that it is a gradual repeatable decline and recovers with an rpm increase leads one to suspect a fuel problem.

Could also be ignition.

I see- makes sense.  :2thumbs:

myk

#10
May 15, 2016, 03:51:06 AM
Quote from: JRH LEE3 on May 14, 2016, 06:29:13 PM
yes, it has power brakes.  I have no idea what my idle speed is set to???  I have always just fine tuned it to ear.......

Does it sound like it could be a vapor lock or NO ??

I'd check the easy stuff first.  If your idle speed is too low the car will stall.  Why don't you turn it up a bit and see what happens...

JRH LEE3

#11
May 15, 2016, 10:02:07 PM
Is was a vacuum leak......thanks guys!!
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