What is the mileage of your truck? If your getting up there in mileage your CP3 could be getting tired. This is common in Duramax trucks. GM Duramax trucks are the only diesels that do not use a lift pump. They use the Injection pump (CP3) to deliver injection pressure to the rail and also suck fuel from the tank through the filter and up to the pump sitting at the motor. That is a long way to suck fuel. If you have any minor air leak you will get a loss in vacuum and starve for fuel. With any fuel maintenance you have to be extra extra clean. I can not stress this enough. Here are the steps I would take.
1...The easiest thing to check is a new filter. If you are using factory style filters you need to clean and maybe replace all seals along with it. This includes the water sensor gasket and the bleeder screw.
2...Is you are reasonably mechanically inclined you can rebuild the filter housing. Autozone, KOI, NAPA will all have filter housing rebuild kits for less than $50. It is all the o-rings and seals for the housing. The housings are very susceptible to dirt and debris at the primer plunger. If you are worried about the work involved you can buy a new housing also. If you get a new housing make sure it is for your year truck. GM slightly changed the hose routing somewhere in 2005-08.
3...Get a NICKTANE filter housing adapter and a Donaldson filter.
http://nicktane.com/osc/product_info.php?cPath=22&products_id=63
http://nicktane.com/osc/product_info.php?cPath=22&products_id=51
This will not always fix the problem. But if you have a week CP3 the larger filter will allow the pump to suck through the filter a little better.
4...The best solution is to install a Lift Pump back at the tank with a good water separator and filter built into one. These are expensive but once done are wonderful. AirDog 2 165 or FASS 150 are great options.
http://atptrucks.com/airdogii165-2001-2010-gm-duramax.html
Feel free to PM me with any questions. I will do my best you help.
good luck
Tony
2008 Silverado 2500HD DMax LTZ cc sb 4x4 EFILive tuned, Blocked, Deleted, Rerouted and removed ;)B&W Turnover ball and 5th Companion
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