carb question
Thread Starter
|
Senior User
Joined: May 2006
Posts: 107
Likes: 0
carb question
I have a 78 f-150 with a 400 and stock carb, motorcraft 2150, my question is about where a wire goes. Right in front of where the throttle is there a round looking thing where the throttle piece rests against is a round piece and a wire comes out of the front part of it. This wire isn't connected to anything on mine, where should this wire connect to? It has a long flat piece of metal on the end of it.
Thanks in advance of any help you can give me
Thanks in advance of any help you can give me
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Yep, that is for sure the idle stop solenoid. The wiring pigtail is missing the plastic casing. Originally it would have gone to fused 12 volts hot-in-RUN, but you shouldn't connect it to anything until you can cover the bare wiring. The solenoid grounds through its mounting bracket, into which it threads.
On carburetors that are so-equipped, the idle stop solenoid is responsible for maintaining the curb idle speed when the engine is running. The idle speed is adjusted by a long screw which moves the idle stop solenoid closer and farther away from the carburetor. When the engine is shut off, the solenoid retracts, and the throttle plates are allowed to (almost) shut. This was used to prevent dieseling, which was a common problem on smog engines that ran at higher combustion chamber temperatures.
On carburetors that are so-equipped, the idle stop solenoid is responsible for maintaining the curb idle speed when the engine is running. The idle speed is adjusted by a long screw which moves the idle stop solenoid closer and farther away from the carburetor. When the engine is shut off, the solenoid retracts, and the throttle plates are allowed to (almost) shut. This was used to prevent dieseling, which was a common problem on smog engines that ran at higher combustion chamber temperatures.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
On my '79, the idle stop solenoid was (I run a 4-barrel now) powered from a 12 volts hot-in-RUN signal coming from a 2-connector pigtail at the firewall. The other connector in the pigtail was the stator signal for the electric choke assist. The hot-in-RUN signal for the idle stop solenoid was protected by a 7.5 amp fuse at the fuse panel labeled "ENG. SOL." for engine solenoid. I'd try and see if the same setup exists on your '78. I'm not up-to-speed on the year-to-year differences.
Thread
Thread Starter
Forum
Replies
Last Post
lazzarruss
1973 - 1979 F-100 & Larger F-Series Trucks
3
Sep 15, 2018 11:13 PM
rauto13
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
3
Nov 17, 2013 09:07 AM
jaspirr
1973 - 1979 F-100 & Larger F-Series Trucks
4
Apr 18, 2010 01:07 PM
BigBody
Big Block V8 - 385 Series (6.1/370, 7.0/429, 7.5/460)
2
Sep 25, 2005 05:32 PM
