CarburetorsCarb discussion and questions. Upgrading a Third Gen carburetor, swapping TBI to carburetor, or TPI to carburetor? Need LG4 or H.O. info? Post it here.
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i have a 87 trans am lg4 carb non cc. there is a plug on top of the carb with two wires comin out of it. one goes into the harness and one is just hanging there. whats it for? whats it do? what do i need to connect the one wire too?
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It's to increase the size of the accelerator pump shot when the engine is cold (or when it's hot... I can't remember which way it works). It's supposed to be plugged into a TVS on the water neck. When the wires aren't plugged in, it behaves like a normal M4ME.
sorry whats a tvs? yes there are two holes on my water neck. bolts in them now. i bought a temp sensor that i was told goes on the water neck. do i plug that wire into that sensor?
Its probably for the idle speed control solenoid.Mostly used when the A/C is running.
No, it's the dual capacity accelerator pump like aperion said.
Quote:
Originally Posted by jaygt
sorry whats a tvs?
Thermal Vacuum Switch.
I'm trying to get a picture of the system in my mind (never seen one in person, just pics on this Board), but I believe this uses a thermal electrical switch (could be wrong).
It's to increase the size of the accelerator pump shot when the engine is cold (or when it's hot... I can't remember which way it works). ... When the wires aren't plugged in, it behaves like a normal M4ME.
Bigger shot ("normal" for any other q-jet) when cold, reduced shot (for reduced emissions) when warm and assumedly not as much needed.
I'm trying to get a picture of the system in my mind (never seen one in person, just pics on this Board), but I believe this uses a thermal electrical switch (could be wrong).
im soo confused. i could use a picture of where to plug this wire in. its just hangin there. its one wire. the other wire from the plug is pluged into the harness on drivers side. i bought the temp sensor for the water neck but its two wire. what do i do. this is crazy how i cant get an awnser to where to plug one single wire.
so this thermal vacume switch. is it also called a temp sensor? all gm could tell me is that there is a temp sensor on my water neck so i got one. its two wires though and i bought the plug and two wires with it. where does this wire up too? i must sound like a newbie. a picture would help soo much. basically where the two wire go from the plug on top of the carb on all lg4,s and the temp sensor on the water neck.
A thermal vacuum switch uses water temperature to control vacuum to a component. Some thermal vacuum switches allow vacuum to the component when cold, some thermal vacuum switches allow vacuum to the component when warm. These can be found both on the thermostat housing and the intake manifold.
A thermal electrical switch uses water temperature to control an electrical signal to a component. Some allow the electricity to the component when cold, some allow electricity to a component when warm. The thermal electrical switch that is the topic of this thread is in the thermostat housing. It is not found on computer controlled 3rd gens. Some 3rd gens have an electric radiator fan and use a thermal electrical switch in the passenger side head. It is a different switch, however.
A thermal sensor, or as they're called on 3rd gens, "coolant temperature sensor", tells the computer what the coolant temperature is so the computer can properly alter fuel and spark control for the temperature the engine is at. It is in the thermostat housing. Your car doesn't have a computer or a CTS.
There is also a temperature gauge sending unit. It is in the driver side head between the #1 and #3 cylinder exhaust ports. On cars that have a temperature light and not a temperature gauge, it is a temperature switch (either on or off).
It appears to me that the solenoid in the carb gets 12 volts in one of the wires, and the other wire goes to the thermal electrical switch. When cold, the switch grounds the wire to complete the circuit and allow the full shot from the accelerator pump. When warm, the switch opens the path to ground and limits the accelerator pump to a lesser shot.
great thanks for all the help. i bought a temp sensor for the water neck but it now has two wires. i have to figure that out. i found an old picture of my engine showing the wires. its the green wire thats not pluged in. i will try to ground it and see what happens
