Engine/Transmission (1998.5 - 2002) fuel cut-off

[andrewkoperdak]

Somebody that knows the answer for sure, please tell me what it is that makes the engine defuel. I thought it was hitting 21 PSI of boost but after some go rounds in another post I thought I would see if I was right or wrong.

Someone mentioned the VP44 could not produce more fueling but I have stage 3 injectors and a stock VP and she puts plenty of fuel in the engine. Which leads me back to sensing boost pressure and then defueling at a set limit.



Your thoughts?



Andy

 

[A Johnson]

First you ask for someone who knows the answer for sure and then you want thoughts. ??



There are a number of things that will cause it to defuel, over temp on intake or coolant, low oil psi, high fuel temp, and over boost are a few examples. The defueling can be a set limit or a sliding degredation depending on the conditions and amount of time the out of range condition exists.



I assume you are talking about a defueling on overboost. I believe if it sees too much boost it will defuel to the AFC no air limit, which is to say it will only give you the amount of fuel that the fuel pump is limited to producing when it sees no boost pressure, which is not very much fuel, thus not very much horespower. Most Cummins products will give a check engine light in any of these conditions, the exception may be when excessive fuel temp is the cause of the derate. In this case it lowers HP in an attempt to get the fuel temp down. Max fuel temp spec is 160* F.



A Johnson