Fuel Delivery Trouble

[8lug]

Hey guys, I've been away for quite a while, I can't visit this site regularly when money is tight Too many good ideas.

I do however have a problem. Symptoms rough idle when cold, lots of black any acceleration over 1/6 throttle increase, also, possible unrelated, my CP3 doesn't seem to be providing much if any pull from the tank, if I have less than a 1/4 tank and park with my nose up it won't start. I had to use my winch to turn myself around on a hill a few weeks back after parking over night.

Is my CP3 causing all these problems? Stock CP3 150,000 miles.

Also, lack of power. I am running tow/economy on my programmer, I ran it up in the higher setting (extreme) and stepped on it to pass someone I got a bang like my tranny slipped and a low fuel rail pressure code thrown, after that it had no power, the more you step on it it would actually decrease in speed (limp mode but no Trans codes)

Thanks.

PS I have a FASS 150 but haven't installed it.

 

[8lug]

BUMP

31 people have looked at this and no input? Any ideas would be appreciated. Thanks.

 

[Burn Down]

Are sure your fuel filter is good? Maybe something in the tank caught in the pickup or further in the hose. One way to check this would be to let get low on fuel and park it nose up, or where ever it won't start, jump out and try the hand primer if you have good fuel there (it gets hard when you pump it) it's more than likely a problem with the cp3 suction side of the pump.

 

[8lug]

I will try that, thanks. Never thought about a blockage pre filter. It is also surging like a pressure regulator or something but only when it's cold.

 

[Burn Down]

If it's starving for fuel it can surge.

 

[8lug]

If it was starving would it blow black? I wouldn't think so... should clean up the exhaust no?

 

[Redbowties88]

the blowing back is most likely it adding pulse because it cant maintain rail pressure..

i would say add the airdog and see if it helps...cause even if the cp3 is shot you'll want the airdog on there for the new one anyway

 

[Stingpuller]

Fuel

I had a 100k lb7 doing the same thing. It would smoke but no power. Done all the test and it was the CP3. Jeff

 

[8lug]

Right on thanks guys, is the answer a high flow rebuild on the cp3 in that case? :coal:

 

[Burn Down]

I just had a chat with my buddy at the dealership, he has seen several lbz trucks come in with failed cp3 pumps (ceramic ball?). He also said that under warranty GM wants the cp3, injectors, fuel lines, & fuel rails replaced from the contamination. Can't see why the lines & rails couldn't be cleaned & reused. I wonder if this isn't what has happened to yours, possibly taking out injectors in the process? That could explain the black smoke.

 

[DAVe3283]

I'd install the AirDog first, and see how it runs. If it makes a big difference (and you don't see any fuel leaks), then your CP3 is probably fine. But if it still have problems (smoke, low rail pressure) your CP3 is probably on its last legs.