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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), GMC Mechanic
Category: GM
Satisfied Customers: 29427
Experience:  GM Grand Master Technician 2007. 14 years experience.
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fuel relief valve on a 2003 duramax 6.6 diesel?..engine stalls..seams

Resolved Question:

Where is the fuel relief valve on a 2003 Duramax 6.6 diesel? When I increase speed fast the engine stalls. If I increase speed slowly it gains speed but seams lazy. Already replaced the fuel and air filter.
Submitted: 4 years ago.
Category: GM
Expert:  GM Tech (Cam) replied 4 years ago.
Hello, I'm Cam. Please include all the details about your issue so I can accurately advise you. I cannot see your vehicle so please be detailed.
This is not usually the relief on this series. So let me ask this. Does the engine seem to crank lots when trying to start?
Customer: replied 4 years ago.

It may have a little extended cranking but it starts every time. This is a 2003 GMC extended cab 4X4 with a 6.6 Durmax 6.6 diesel with a automatic trans. The fuel mileage seems to be ok but it is does seem to be lazy.

Expert:  GM Tech (Cam) replied 4 years ago.
If you pump the plunger of the fuel filter and primer, does fuel leak out anywhere?


the relief valve is on the drivers side of teh fuel rail, center under the turbo inlet area.
Customer: replied 4 years ago.

No. I have replaced to fuel filter and the air filter. If I steadly increase te speed it does ok, but when the throdle is open quickly It stalls but does not die out.

Expert:  GM Tech (Cam) replied 4 years ago.
Ok. So the test that Is easiest is to watch on a scan tool what the pressure is doing. Even better is to use the scanner to watch the actual fuel rail pressure as you manually increase pressure to see if it holds and stays with in 2 MPA. IF it does. If it does drop then look at the calculated fuel rate. 800-900 is normal and more than this could be injectos that are notorious for failing.
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