Cold Start Injector

General Information

Info - V6 models only


"The cold start valve is used to provide additional fuel during the crank mode to improve cold start-ups. This circuit is important, when engine coolant temperature is low, because the other injectors are not pulsed "on" long enough to provide the needed amount of fuel to start. The circuit is activated only in the crank mode. The power is supplied directly from the starter solenoid and is controlled by a cold start switch, which provides a ground path for the valve during cranking, when engine coolant is below 95 F (35 C).
The cold start fuel injection switch contains a bimetal switch, which opens at a specified coolant temperature. This bimetal (switch) is also heated by the winding in the cold start fuel injection switch, which allows the valve to stay "on" for 8 seconds at -5 F (-20 C). The time the switch will stay closed varies inversely with coolant temperature. In other words, as the coolant temperature goes up, the cold start valve "on" time goes down"

The cold start injector injects fuel into the manifold. The rest of the injectors are also in the manifold right above the heads.

From: Scott Backer


I have looked into the operation of the CSV. Here's how it works:

The CSV is powered by a line that's *hot only in crank mode*!!! I.e. once the engine runs, the CSV is shut off because there's no more power!
The CSV-switch that switches the CSV is a simple bi-metal switch. It comes on below 100F coolant temp, but is heated if the starter is cranking. In effect, even if you crank for a longer period of time, the bi-metal will be heated and the switch turns off the CSV.

How to test: Remove the fuel injection fuses. Use a fuel pressure gauge. Turn on ignition (fuel pump will come on). Fuel pressure should remain steady (otherwise you have an injector leak). Crank engine. it won't come on since the CSV injector doesn't provide enough fuel to actually start engine. The pressure should drop by 3 psi until the CSV-switch shuts the CSV off. If pressure doesn't go back up after a few seconds, either the CSV-switch is bad (always on) or the CSV is sticking.

To test the switch, I'd propose to use a test-light instead of the injector. With the engine cold, it should come on for a few seconds (the colder the engine, the longer) and then go off.

No electronic circuit in the CSV-switch! Simple off/on operation.

From: Oliver Scholz

Removal and Installation

Removal - V6 models only

This is the way I took the cold start injector and tube off, taking them off as a unit is definately the easiest way.

  1. Remove the plenum.
  2. Unscrew the fitted end of the cold start tube from the fuel rail.
  3. Unbolt the cold start injector from the intake manifold. (Small bolt, about 8-10mm in size)
  4. It is probably easiest to pull the injector out of the manifold first, and then lift up to pull the tube out of the rail.

NOTE: Be careful with those O-rings, GM doesn't sell them seperately, only in a $15 kit with a whole new tube. I had to replace one, and couldn't find one at any of the local auto parts stores. Luckily, I found one at a plumbing/mechanical supply shop.

From: Sketch

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