Throtle stop solenoid
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
The throttle solenoid does not serve for fast idle or AC. The only purpose of the throttle solenoid is to prevent dieseling. On carburetors equipped with this solenoid, the solenoid holds curb idle while the motor is running. When you cut power, the solenoid retracts, and the throttle plates shut completely. This cuts off any path of air and fuel to enter the engine, to eliminate dieseling. The throttle solenoid power is sourced from hot-in-run power.
Fast idle is controlled by a mechanical fast idle linkage. If your engine will not idle with AC engaged, you have a vacuum leak, improper idle fuel mixture, or too low of a curb idle speed.
Fast idle is controlled by a mechanical fast idle linkage. If your engine will not idle with AC engaged, you have a vacuum leak, improper idle fuel mixture, or too low of a curb idle speed.
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
Likes: 787
From: Simi Valley, CA
Without the carburetor tag number, looking up the correct parts is impossible.
There are two possible solenoids:
9S520: Solenoid and Dashpot Assy: 1977, there are THREE different ones.
9D856: Emission Control Solenoid: 1977, there are SIX different ones.
The carb differences: CA, non CA / Before/after serial numbers / High-Altitude, non High Altitude. In NM, you may have a High-Altitude carb.
IF the DSO code on your Warranty Plate is either 71 or 72, you have a sold new in CA vehicle.
There are two possible solenoids:
9S520: Solenoid and Dashpot Assy: 1977, there are THREE different ones.
9D856: Emission Control Solenoid: 1977, there are SIX different ones.
The carb differences: CA, non CA / Before/after serial numbers / High-Altitude, non High Altitude. In NM, you may have a High-Altitude carb.
IF the DSO code on your Warranty Plate is either 71 or 72, you have a sold new in CA vehicle.
Thread Starter
|
Lead Driver
Joined: Nov 2000
Posts: 6,646
Likes: 352
From: Albuquerque
Regardless of intended use I use mine for an idle bump when the AC compressor is on and on a switch for winter fast idle help (cold natured). I don't really care what the original ap was. There were some that had two positions which might be nice.
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
Likes: 787
From: Simi Valley, CA
Throttle Emission Control Solenoid, depending on the carb ID number:
D7DZ9D856A (Motorcraft CS4) / Obsolete
GREEN SALES CO. in Cincinnati OH has THREE: 800-543-4959.
LINCOLN OLD PARTS STORE in Clearwater FL has ONE: 727-445-1091.
Or...
D7TZ9D856A (Motorcraft CS24) / Obsolete
KLIMESH AUTO SALES (Ford Dealer) in Calmar IA has ONE: 563-562-3241.
No other Ford Dealer or obsolete parts vendor has either one.
Application: 1977/78 F100/350 351M/400 C6 without CA emission.
D7DZ9D856A (Motorcraft CS4) / Obsolete
GREEN SALES CO. in Cincinnati OH has THREE: 800-543-4959.
LINCOLN OLD PARTS STORE in Clearwater FL has ONE: 727-445-1091.
Or...
D7TZ9D856A (Motorcraft CS24) / Obsolete
KLIMESH AUTO SALES (Ford Dealer) in Calmar IA has ONE: 563-562-3241.
No other Ford Dealer or obsolete parts vendor has either one.
Application: 1977/78 F100/350 351M/400 C6 without CA emission.
Post Fiend
Joined: Jul 2004
Posts: 8,786
Likes: 28
From: Northern California
The throttle solenoid does not serve for fast idle or AC. The only purpose of the throttle solenoid is to prevent dieseling. On carburetors equipped with this solenoid, the solenoid holds curb idle while the motor is running. When you cut power, the solenoid retracts, and the throttle plates shut completely. This cuts off any path of air and fuel to enter the engine, to eliminate dieseling. The throttle solenoid power is sourced from hot-in-run power.
Fast idle is controlled by a mechanical fast idle linkage. If your engine will not idle with AC engaged, you have a vacuum leak, improper idle fuel mixture, or too low of a curb idle speed.
Fast idle is controlled by a mechanical fast idle linkage. If your engine will not idle with AC engaged, you have a vacuum leak, improper idle fuel mixture, or too low of a curb idle speed.
Trending Topics
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Do you know what year this started? I was under the impression that this wasn't until later in the application. I thought it was outside of the 73-79 generation but I could be wrong.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 6 Best Deals Available on New Fords & Lincolns Right Now
Brett Foote
This Hennessey Takes the Expedition Tremor's Off-Roading Capability to the Next Level
Verdad Gallardo
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Post Fiend
Joined: Jul 2004
Posts: 8,786
Likes: 28
From: Northern California
Can't be 100%, but from my information my closest guess would be. 1977.
This is the first year when it appears in the wiring diagrams, for this specificly designed purpose. I also notice it matches the year in the part number also.
And just for clarification, not all models had one. This is also apparent in the wiring diagram.
This is the first year when it appears in the wiring diagrams, for this specificly designed purpose. I also notice it matches the year in the part number also.
And just for clarification, not all models had one. This is also apparent in the wiring diagram.
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
Likes: 787
From: Simi Valley, CA
Info source:
1973/79 Ford LIGHT Truck Parts Catalog / Carburetor Section 95 / Parts List #37N.
btw: This parts catalog is available on a CD from hipoparts.com for around 25 bucks.
Thread
Thread Starter
Forum
Replies
Last Post
1977, ac, buy, cs4, d7dz9d856a, diesel, difference, f150, ford, idle, motorcraft, ranger, solenoid, stop, throttle
