If your 6.5L diesel with the DS4 electronic injection pump is showing symptoms of stalling, hard starting, and hesitation, you may not need to replace the injection pump just yet!
The PMD (Pump Mounted Driver) is prone to failure from constant heating and cooling when mounted inside the engine compartment and needs to be moved out in order to assure maximum performance and long service life. The PMD Isolator mounts on the front skid plate, below the radiator. This is a very nice, tidy installation and provides much cooler and more consistent temperatures that will keep the PMD from failing. It is fully assembled and ready to install.
GM Technical Service Bulletin #77-63-06Ab states that: "stalling, hard starting, and hesitation are symptoms of a failing PMD (Pump Mounted Driver) module." These symptoms usually (but not always) set a code 35 or 36 in the 1994 - 1995 models, or a code 1216 in the 1996 - up models. Often when this problem is diagnosed at a dealership or repair shop, the customer is told that the injection pump needs to be replaced. But in most cases, the PMD module can simply be replaced for a fraction of the price.
The PMD module, (also referred to as the "Fuel Solonoid Driver") has been a major problem for Chevy / GMC 6.5L diesel owners since the introduction of the 6.5L electronically controlled DS4 fuel injection pump. It has been determined that heat is the primary cause of PMD failures. The PMD is mounted to the side of the fuel injection pump from the factory. But the injection pump does not provide adequate cooling to keep the PMD functional. Once the engine begins showing symptoms of hesitating, stalling and hard starting, the problem will only worsen with time. The problem only becomes more serious when considering the potential danger of your engine stalling in a situation such as pulling into heavy traffic or descending a steep hill and losing the use of power brakes and steering. It is recomended that the PMD is replaced.
Tests show that when using the PMD Cooler, PMD temperatures will drop considerably depending on driving conditions. These temperature drops will seriously increase the life of the PMD and can save you money from towing and costly repairs. Installation is quick, simple and does not require any modifications or special tools. The PMD Cooler kit comes with everything needed to mount the assembly to the intake manifold of your truck.
