Rough idle---Help!!
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Junior User
Joined: Jan 2005
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From: South Carolina
Rough idle---Help!!
1980 f100 I6-300--1 barrel carb--manual trans--idles great--around 500 rpms-- until the weather becomes cool and damp and then it tries to shut off,any ideas, or thoughts on this would be appreciated!
Postmaster
Joined: Jul 2003
Posts: 2,711
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From: Pittsburgh
When was the last time the motor was tuned up? Cap, rotor , wires, whole nine yards? All the 300's i've owned (3 of them now) would idle horribly in cold and wet weather (especially the rain) until i did a full tuneup on it.
Another thing that helps is that I take a can of silicone sealant. With the motor COLD and OFF spray down the entire ignition system from dizzy to plugs. Go eat lunch, give it PLENTY of time to dry. After that, the moisture is sealed out and everything is faine. I say let it dry because that stuff is incredibly flammable until dry. I've seen a car reduced to nearly nothing from a guy trying to start his car immediately after spraying everything down. A plug wire arced and there was no extinguisher anywhere around. It was rather impressive.
Justin
Another thing that helps is that I take a can of silicone sealant. With the motor COLD and OFF spray down the entire ignition system from dizzy to plugs. Go eat lunch, give it PLENTY of time to dry. After that, the moisture is sealed out and everything is faine. I say let it dry because that stuff is incredibly flammable until dry. I've seen a car reduced to nearly nothing from a guy trying to start his car immediately after spraying everything down. A plug wire arced and there was no extinguisher anywhere around. It was rather impressive.
Justin
Postmaster
Joined: May 2004
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There was some recent discussion of carburetor icing when cold and wet.
Do you still have the EGR hooked up? It brings warm exhaust air up to the carb base, preventing icing. Also, check the valve on the exhaust pipe for operation....when cold, it closes off somewhat, keeping the hot exhaust air routed to the EGR, etc. That valve (heat riser) should be able to rotate by hand, and return when released.
Do you still have the EGR hooked up? It brings warm exhaust air up to the carb base, preventing icing. Also, check the valve on the exhaust pipe for operation....when cold, it closes off somewhat, keeping the hot exhaust air routed to the EGR, etc. That valve (heat riser) should be able to rotate by hand, and return when released.
