67 ranchero will not run at idle speed

Hello Larry,

Without the car running... You should be able to open
the throttle.. and literally DROP it back to idle...

Observe the action of the THROTTLE RETURN
DASH-POTT should visibly SLOW the RETURN
of the throttle linkage like a door closer...

If you do not SEE the slowess... the dashpot
should be replaced (they are getting SCARCE).

SIX CYLINDER (EXAMPLE (only))
http://www.ebay.com/itm/NORS-65-67-MUSTANG-64-67-MERCURY-COMET-FORD-FAIRLANE-FALCON-DASH-POT-C2DZ9B549A-/142309387430?hash=item21224ceca6:g:kE8AAOSwo4pYmKnd&vxp=mtr


You will need to have the THROTTLE RETURN DASH-POT
on your (unspecified) carburetor
tested and adjusted... and the IDLE SPEED correctly set.

Idle Speed and a slow rate of RPM reduction is
critical to the proper function...

Some LESSOR "mechanics" will attempt to raise the
IDLE SPEED to compensate for a malfunctioning
DASHPOT... This will PROFOUNDLY exacerbate
the problem.

Throttle return dashpot (various pictures)
Go to Bing homepage

example DASHPOT (six cylinder)
NORS 65 67 MUSTANG 64 67 MERCURY COMET FORD FAIRLANE FALCON DASH POT...

example 1968 302/5.0L: Falcon, Mustang 2BBL carb
Carter 202 737 Carburetor Dashpot Ford 2 BBL Carburetors Replaces D7ZZ...

Hope this helps

Carnac the Magnificent

Disconnect the fuel line from the carb. Put the fuel line in a container and crank the engine for 4 or 5 seconds. You should see good squirts of fuel. Better yet put a fuel pressure gauge in line just before the carb. You should have 4-7 psi. It might be quick to get a gas jug a start a syphon to the carb. Dont forget to catch the fuel from the disconnected fuel line. If it starts right up its probably the fuel pump. If not the carb may need a good cleaning and rebuild. Check float bowl level. Check idle air screw adjustment.

carb settings such as idle mixture screw, choke settings, vacuum leaks at base or vacuum lines.Does it stay running off idle?

A 1967 Ford would have a carb, so no control valve would be used.
The cam under the choke would provide a fast idle when the engine is cold.

Idle speed control valve stuck(clean with carb cleaner), possible split in vacuum pipe or one has come off. Check all vac pipes, spray around vac pipes with the carb cleaner with the engine running, see if engine speed changes, if it does you have a vac leak.

fast idle speed screw, works off the fast idle cam which the choke adjustment sets, it works together by linkages. This is the raised idle speed setting you need to keep a cold engine running. First you set the idle speed by the idle speed screw with engine at normal operating temperature. Then you set the linkage up so the cam is on a raised step, throttle will be held on that raised step. then you can turn the idle speed screw to get idle at about 1500-1800 rpm. Now when you start engine cold, choke will set the fast idle cam on that raised step- when engine starts and runs it should be running at your fast idle setting. That's how it supposed to work, you just have to get everything adjusted right. I hate carburetors, they never stay adjusted right. Considering their complexity and small mechanical parts, no wonder.

carb problem or vacuum leak at carb base gasket or intake manifold

it's on the throttle body. Here's a Quest with same 3.0L engine. These often need cleaning with carb or throttle body cleaner

Idle Air Control (IAC) Valve When the engine (6007) is running but not at idle, the throttle valve controls the amount of air admitted into the engine. The powertrain control module (PCM) (12A650) increases the fuel injection output in proportion to the increased airflow to achieve the appropriate air/fuel ratio. During idle, the throttle valve is almost fully closed. It is therefore necessary for the idle air control system to supply air for combustion during idle. The idle air control (IAC) valve allows a metered amount of air to enter the intake manifold (9424). The camshaft position (CMP) sensor detects engine speed and sends a signal to the PCM. The PCM sends a duty cycle (On/Off) signal to the IAC valve which allows additional air to enter the intake manifold. Air is added by the IAC valve to maintain the set lowest idle speed at which the engine can operate. The idle speed adjusting screw allows adjustment of the airflow into the intake manifold.


Fast Idle Control (FIC) Solenoid The fast idle control (FIC) solenoid helps maintain a constant idle speed while the air conditioning is operating. When the air conditioning is turned on, the front climate control panel sends out two signals. One signal is sent to the powertrain control module (PCM) (12A650) to engage the A/C compressor (19703). The second signal is a ground signal sent to the FIC solenoid relay, to engage the FIC solenoid. The FIC solenoid supplies additional air to adjust the increased engine load.

Here is the most common cause of surges and stalls at stops and low erratic idle speed and rough idle, it is the idle speed control air-bypass valve and throttle valve (IAC for short), they get full of gunk over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.

Check your Ignition timing before anything
check your plugs see what color they are
red or orange means carb is to lean , black
or oil means to rich then you can go from there
and set mixture screws on carb , let me no how you make out .