Possible limp mode???
 

I have experienced this problem about 4 times so far. Here in Tide country the summers are fairly warm, so I will leave my 04 dmax running along with the a/c, sometimes for several minutes. When I get back at get going it acts like it's not taking fuel, then it stumbles, the check engine comes on and the engine runs crappy maybe 2000 rpm 40-50 mph tops. Plug in my programmer and getting a P0087 code.... any suggestions as to what this could be.?. I know it's a fuel pressure issue. The HD has 157000 miles on it.

ok, first off, that is definately limp mode. The code is low rail pressure. It can be caused by several things. By chance are you running your programmer at or above 100hp when this happens? Cheapest thing to do would be change your fuel filter. Have you ran low of fuel lately or not changed the filter every 10,000 miles? A full scan could show restriction in the fuel system but, a filter is half the price of paying someone to plug you in. If you have a new filter and have NOT ran low on fuel resentely it could be the FCA (fuel control acuator) it's on the back of the cp3 pump. and I know that when guys want to run big tunes they usually step up and get the fuel rail shim kit which holds high rail pressure. My guess would be filter 1st

Possible limp mode
 

Thanks Ctane for your response. I am running with my programmer set high, but it has always been on these settings except when towing. Haven't run low of fuel to the point of the light coming on in months, usually top off when it hits a quater tank, unless on the interstate. Run diesel additive, with cetane and lubricants. Fuel filter sometimes goes longer than 10,000, but just put a new ac delco on two to three weeks ago.

Hey boss, I had this problem in my duramax when I ran my big chip. Everything Ctane said are correct. Those are all possible but typically what happens is that the truck is using more fuel than it can get. This is because the truck also returns fuel to the tank. Two options order a fuel release valve shim kit Or buy a Race fuel valve. Do a google search for these and you will find plenty of results. I opted for the Race fuel valve. With this the truck returns no fuel back to the tank. There is no adverse effects from this it works great and problem solved. Good Luck buddy. ps. the race valve should run 50 bucks or less

Jshannon, Thanks for posting that up... I'm glad someone that had the same problem spoke up! I put a shim kit on my buddy's and it seems to have fixed it. Although, the edge on high still de-fuels during shifting (safety). I'm guessing that the CP3 just gets weaker as miles go on...

Ctane, Jshannon2 I really appreciate your input. That makes sence. Never thought about the fuel Over loading . Might could back the program off a little till I can get that shim kit in . Thanks again... Was really dreading changing that cp3 pump