One of the ways engineers have been able to help an engine start on those cold winter days is with a part called the cold start valve. This valve is really an extra injector within the air intake distribution valve in in the fuel rail line. This cold start valve works to inject fuel into the air intake stream when it is too cold to start through normal fuel delivery. This is controlled through a thermo time switch. Locating, and then replacing, the cold start valve is something that will take the use of a repair manual, mechanics tools and patience.
Step 1: Be Familiar with Repair Manual
Replacing the cold start valve can be a little bit tricky. There are some steps in the process that may be taken for granted, but do require great care. The best way to find out all of the small, but very important tips, is to read through a repair manual on your specific vehicle. The cold start valve, while does the same job in all engines, is installed a little differently.
Step 2: Purchase Correct Cold Start Valve
Many times the aftermarket parts that are available are not exactly like the original. Check to make sure that you can purchase an original part for your vehicle before buying an aftermarket product. It may cost you a few more dollars, but will be well worth the extra expense as it will fit properly and work more efficiently.
Step 3: Locate Cold Start Valve
In most makes the cold start valve will be located within the air intake distributor. Remove the air intake cover, and the air filter. You should notice a small valve that looks like a fuel injector within the assembly. If you have problems locating the cold start valve, refer to the specific repair manual for your engine.
Step 4: Disconnect Battery and Valve
Using a ratchet or the appropriate wrench, loosen the bolts on the battery terminals. Remove the battery terminals and set them in a safe area. Set up your drop light so that you can work with plenty of light. Locate the cold start valve again and disconnect the electrical lead from the outside terminal. A screwdriver should be used as a lever to pry up the plastic tab. Work carefully so you do not break the small tab. Pull the wiring harness out from the valve.
Step 5: Remove Cold Start Valve
Look for some small screws that hold the cold start valve to the air intake assembly. Remove the screws very carefully as they can easily break from too much pressure. Once they are removed, unscrew the cold start valve from the fuel rail.
Step 6: Install New Valve
Once the old cold start valve is removed you will need to use a clean shop rag to clean out the threads and surrounding area. Set the new valve in place and screw it into the fuel rail. Make sure that you line up the threads right and do not cross thread the part.
Step 7: Connect Wiring and Start
Connect the wiring harness to the valve and replace the battery terminals. Turn the key to 'On' and let the fuel pump start and bring in fuel before starting the engine.