Cold Nature

[RagingCajun]

Hi,
I’m post this guestion for a friend which has a 2002 dodge 5.9 five speed. The issue is when the engine is cold you can drive down the road and the truck will stall and only go about 50 mph and you can try and accelerate but will not. He said you can slow down to around 30 mph then accelerate and it will speed up. Once the engine warns up it works normal. He has change the lift pump out and it’s acting the same.
Does anyone have any ideas on what could be the problem?

Thanks

 

[gtwitch]

Places to start if you do not have codes set! Start with the APPS (throttle position sensor ) , then the cam sensor and possible the MAP sensor but all of these should set codes!! Also, fuel filter restricted. Blue Chip has a great set of trouble shooting guides that you can download from his site.
gtwitch in wyoming

 

[DavidC]

Bluechips site
Low Power, Cold

If the truck is gutless when driving for the first little while after start up cold, and then all of a sudden takes off and runs fine, this is almost always a bad computer on top of the Injection Pump. This means replace the Injection Pump. If you have a code 237 with this symptom, address that first by checking MAP sensor signal voltage, as described below. If you can predict when it is going to do this naughty thing, try heating the computer on top of the pump with a hair dryer for a few minutes, and if it runs fine right off, you know I am right. If that doesn't fix it, do the APPS test as described in "Dead Pedal" above to determine if the voltages are doing what they should when cold, to make sure it is not caused by low voltage from the APPS. If the voltage doesn't go up when the pedal is pressed, then the ECM won't tell the injection pump to deliver more fuel, so you can blame the APPS. If the voltage goes up when you press on the pedal, then the APPS is working correctly, and it IS most likely caused by the computer on the top of the injection pump, or some mechanical issue inside it.

Dave