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Pete, Auto Service Technician
Category: Chevy
Satisfied Customers: 24140
Experience:  14 years GM dealer Technician.
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I have a 2007.5 3500hd LMM duramax. I have replaced cp3

Customer Question

i have a 2007.5 3500hd LMM duramax . I have replaced cp3 pump , installed lift pump by the fuel tank , installed race plug in the left fuel rail and I am pulling a 20000 lb trailer and the poo87 code set
JA: Has the vehicle turned into a gas hog? And how does it start -- same as usual?
Customer: starts same as usual but I noticed tonight I used a 1/4 tank of fuel fast
JA: What is the model of your '18000 Chevy?
Customer: 3500hd
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: I replaced the cp3 pump , removed the factory fuel filter and put a lift pump and filter assy on the frame . it is set at 11psi . I also just put the fuel rail race plug in the left fuel rail, HELP
JA: Anything else you think the mechanic should know?
Customer: it runs great , my wife noticed a little more smoke than usual when I was getting on the interstate , I went about 45 miles and turned around . it starts good and runs smoothe
Submitted: 2 months ago.
Category: Chevy
Expert:  Pete replied 2 months ago.

My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

One of the most common causes for excess fuel use,the fault code that has set here and smoke is one or more of the fuel injectors leaking down into the cylinders.I have had to replace several of these before for this fault here.If you have not had the fuel injectors tested to see if one or more are found to be an issue this needs done.You only need to replace the injectors that are at fault here.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service,your 5 star rating is appreciated.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete