GMC Chev 6.5L Stalling
- SYMPTOM: Your 6.5L Diesel stalls just as if someone had reached over and turned off the ignition switch.
- CAUSE: There are two main causes. The first and most common is the PMD (also called FSD). The other possibility is the Optical Sensor located in the pump itself.
- DIAGNOSIS: OR "How do I know what to replace?" Simply put, if your check engine light is not on and you experience stalling, it is a 95+ percent certainty that you need a new PMD. If your check engine light is on, you need to get your codes checked. Gillett Diesel Service will do this for free. If you ONLY have codes P1216, P1217, 35, 36 or any combination of those, you need just the PMD. If you have codes P0251 or PO370, 17, 18, or any combination of those, you should consider the injection pump suspect.
- Tech Tip: If your truck stalls and will not re-start you can often get it going again by putting a cold wet rag on the PMD, or by carefully pouring a cup of cold water on it.
- So what is this PMD? PMD stands for Pump Mounted Driver. The same part is also called an FSD or Fuel Solenoid Driver. (One is GM terminology, the other Stanadyne terminology). It is a "black box" about the size of a pack of cards mounted on the driver's side of the injection pump.
- Is there anything else I should check before I buy ? YES!
- Check to be sure your lift pump is running. The lift pump delivers fuel to the injection pump and is located on the frame rail under the driver's seat. The lift pump will NOT cause stalling, but when it goes bad, the injection pump runs hotter which shortens PMD life. See lift pump under products for instructions on checking the lift pump.
- Make sure you have good clean fuel with no water
- For the very thorough individual: Check all electrical connections - battery terminals, engine and body grounds, and all fuel injection pump wiring including the multiple grounds on the intake manifold. With the batteries disconnected open up all connections (including those at the bulkhead) and look for loose or corroded connections, but do not spread open the terminals. Take your time and look carefully for chafed wiring. One connector of particular interest is the large15-way connector near the back of the intake manifold where the main engine harness meets the fuel injection harness which then runs forward under the intake to the injection pump. This connector is commonly the site of severe corrosion, especially in northern states and may cause a variety of intermittent problems.
- Those who are technically oriented and equipped with the proper tools, or who have a hard to solve no-start issue, can follow our in depth "6.5L No-Start Guide"
- If your truck over-responds to the throttle and revs up very rapidly at only light throttle application, or revs up on its own, internal injection pump wear is almost certainly the cause.
- In 99% of cases if you have the classic 6.5L stalling (and no optical sensor codes) the problem is the PMD.
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