Question-------------------------
Followup To
Question -
My wife is experiencing occasional stalling on her truck. The engines stalls while driving, but starts up again easily. We had this same problem a few years back and had it checked by a GM truck service center. They said they never found anything wrong, yet it never happened again????? The injector pump has been replaced (under extended warranty) since the first stalling episodes. She said it doesn't sputter and just quits without warning. She rolls to a stop and it starts back up. Any suggestions?
Thank You,
Pat Cassidy
219 473-5190
Answer -
Pat,
Unfortunately, many of the electronic GM diesels have this problem.
The problem is twofold: A diesel is supposed to use excess diesel fuel to cool its injection pump. This is accomplished by use of an electric fuel transfer (lift) pump that is inline with the fuel line running from the fuel tank. Since this is the accepted standard, GM elected to locate the Pump Mounted Driver (PMD) which is also called the Fuel Solenoid Driver (FSD) on the side of the injection pump. It is about the size of a deck of playing cards and is black in color. This device controls the fuel injection pump.
The other part of the problem is that GM, in its infinite wisdom, decided that the diesel fuel flow would not shut down in an accident and they routed power for the transfer pump through the oil pressure switch (OPS). The problem with this design is that the oil pressure switch contacts are good for about half of an Amp of current but the transfer pump needs about four Amps. This causes the contacts to burn out and stop power to the transfer pump.
Ironically, most 6.5s will still start and run with a bad OPS. The reduced fuel flow, however, causes the PMD/FSD to run hotter and that is bad for the electronics inside of it.
Cure?
Two parts.
First, the transfer pump needs to work properly. In my opinion, this should simply be power run directly to the transfer pump when the key is in the "Run" position. In other words, do not use the OPS.
Second, remote mount the PMD/FSD to a location where it can stay cool. There are kits available for this purpose. You do not need to remove your old PMD/FSD (which is likely bad anyway) but you must disconnect the harness leading to it to plug in the extension harness. The PMD/FSD often winds up near the front bumper or in the intake air stream to the air filter. Needless to say, it stays cooler and does not cause the stalling issues that you are experiencing.
Where can I get a remote mount kit? Are there different types?
AnswerThey are available on eBay from time to time under "6.5 diesel."
www.kennedydiesel.com and www.heathdiesel.com sell them.
There are different types. Some just provide a heat sink that mounts on the intake manifold. Others provide a heat sink and a remote cable.
Generally, moving the PMD/FSD as far away as possible from the engine heat is the best choice.
