Idle Only With Full Choke?

Jared Zecchel

New Member
Oct 20, 2015
Hey everyone, in need of a little advice.

My engine was running fine (maybe a little too rich) until I swapped the spark plugs. All of a sudden the engine starts misfiring and running terribly even after i checked the gaps.

I watched the mechanic down the street tweak the carb a little and he seemed to set everything strait.

Maybe a week later it starts running crappy again. I took it back and he said that the engine was flooding and to rebuild/buy a new carb.

Now it wont idle unless the choke is fully on which makes me think that the engine isn't flooding but rather it has a vacuum leak.

I rebuilt the carb to be on the safe side but still nothing.
I tried the WD40/Carb cleaner spray trick but still nada.

I pumped a bit of smoke in there and there seemed to be a pinhole leak by the opening for the throttle rod but not enough that i would suspect it to make such a drastic difference in the car's performance.

Any idea's?
  • Sponsors(?)

horse sence

That $5 hooker turn out to be a guy
Mod Dude
Nov 29, 1999
Wile Coyote's stunt double
If it is a automatic check the vacuum line to the modulator on the trans it may have a split the rubber line of even off .
Check it at the back of the carb. also . Also check for a missing rubber nipple that should be capping off an un used vacuum port .

Jared Zecchel

New Member
Oct 20, 2015
Vacuum lines are fine. Just replaced them.
All signs point to a fuel delivery problem.
Apparently I didn't clean the jets as well as I thought.
Took it out and did a whole new number on them and now she idles nicely.

Vacuum is 20Hg's idling but 15 when I slip it in gear.
Is it normal to drop so significantly?
Thread starter Similar threads Forum Replies Date
D Poor idle after full intake install SN95 4.6L Mustang Tech 3
M RPM Drops to idle intermittently when fuel tank is 1/4 full 1996 - 2004 SN95 Mustang -General/Talk- 2
danielhv Bad Idle Air Control Valve? Digital Self-tuning Forum 1
J Idle Adjustment Issues 2.3 Turbo fuel injectedto 2.3L (N/A & Turbo) Tech 1
0 4.6 2v SOHC 2k rpm Idle, help reading engine data SN95 4.6L Mustang Tech 1
I Microsquirt idle after clutch engagement Digital Self-tuning Forum 1
africansnowowl Engine Another rough idle thread Fox 5.0 Mustang Tech 7
J Looking for 2005 GT OBD2 idle sensor reading 2005 - 2014 S-197 Mustang -General/Talk- 2
J Engine New Manifold nightmare idle and stall 2005 - 2009 Specific Tech 4
C 2013 GT low oil pressure at low RPMs or idle 2010 - 2014 Specific Tech 0
R Engine Remove the Idiot from the equation. Idle/hesitation issue. Fox 5.0 Mustang Tech 3
C 2014 Mustang Gt/Cs Idle and dying issue 2010 - 2014 Specific Tech 2
T MS3 AC Idle Up Settings Digital Self-tuning Forum 1
93silverlx50 Engine Car in limp mode, fuel spitting out of tailpipes, missing rough idle Fox 5.0 Mustang Tech 9
markinms Engine Should Auto Trans Be in Drive When Setting Base Idle Fox 5.0 Mustang Tech 7
R Fuel Throttle body idle screw 1994 - 1995 Specific Tech 2
darryl paarman A/C idle up control- Low input or High. ? Digital Self-tuning Forum 2
C Engine Gray smoke from exhaust. Smells like gas. Fox 5.0 Mustang Tech 15
lamrith New MSPnP2 in 94 Mustang, need help getting stable idle once warmed up. Digital Self-tuning Forum 1
J Idle issue still!! Replaced several parts.. looking for more ideas!! Fox 5.0 Mustang Tech 12
G 1998 3.8L V6 overheating at idle, gauge doesn’t go up. SN95 V6 Mustang Tech 3
bmgstang Need help with tune high idle Digital Self-tuning Forum 7
S Another Idle surge post with microsquirt Digital Self-tuning Forum 5
H Engine Tach goes to zero,engine goes to idle on 87 GT Fox 5.0 Mustang Tech 10
D 1994 Mustang Gt erratic idle 1994 - 1995 Specific Tech 1
A New fox owner, idle issues need some advice Fox 5.0 Mustang Tech 20
Mixveez Bad idle and dying in neutral. Fox 5.0 Mustang Tech 5
C Microsquirt tuning and surging idle problems Digital Self-tuning Forum 7
L High Idle and Hanging RPM. Tried everything, still no fix. SN95 4.6L Mustang Tech 0
J 2000 GT Idle/Running Issues SN95 4.6L Mustang Tech 6
9 Air Condition Idle up with 2-speed fan (MSPNP Gen 2 V1.2) Digital Self-tuning Forum 8
maisonmays22 Cannot figure out why my engine dies at idle Digital Self-tuning Forum 11
R Engine My 95 gt idling rough 1994 - 1995 Specific Tech 5
MSTNGGRL1995 Rough, loping idle and random attempts to die 1994 - 1995 Specific Tech 1
T Engine Foxbody idling surging and stalling Fox 5.0 Mustang Tech 10
B Slight surging idle issues Digital Self-tuning Forum 14
K Engine New Built Engine - Rough Start and Idle Surge Fox 5.0 Mustang Tech 3
G Engine Idle fussy only when 1st starting Fox 5.0 Mustang Tech 7
S Megasquirt PNP2 460SBF startup/idle issues Digital Self-tuning Forum 9
W 97 Mustang GT to 2011 Crown Vic Swap 95k Miles (Knock at idle) 1996 - 2004 SN95 Mustang -General/Talk- 1
Michael sommers 02 mustang gt auto knock only at idle in gear. SN95 4.6L Mustang Tech 2
Michael sommers 02 mustang gt auto knocking only when warm at idle in gear. 1996 - 2004 SN95 Mustang -General/Talk- 0
darryl paarman After revision - now hanging idle - Digital Self-tuning Forum 30
8 Plz Help! ‘88 Mustang will not idle and runs poorly Fox 5.0 Mustang Tech 4
F Idle Fluctuation Issue 98 GT SN95 4.6L Mustang Tech 0
D Engine Idle issues Fox 5.0 Mustang Tech 23
wolfheads Irratic idle 2005 - 2009 Specific Tech 3
H Idle problem 2005 - 2009 Specific Tech 9
paddyrk Engine Hot idle oil pressure Fox 5.0 Mustang Tech 7
S 2000 Mustang GT surging idle/cruising SN95 4.6L Mustang Tech 3
Similar threads