12 valve Fuel system/injection pump pressure

[Cummins Driver]

Im just curious if anyone has an answer for this.

When you have stock governor springs in a P-pump, and it defuels around 3k RPM, it just quits pulling and runs smooth there.

When you have a 4k, and say you dont have the volume of fuel you need to pull past 3k under load smoothly, then how come it starts sputtering and popping instead of just stop gaining RPM like it does with stock springs and plenty of fuel supply?

Just something i got to thinking about and was curious if anyone knew the answer.

Eric

 

[SSpeeDEMONSS]

probably because its getting some fuel but not enough. whereas with the gov springs its the same as taking your foot out of it a little. thats how i see it.

Garrett

 

[Lance]

ya, when the RPMs get high enough, the gov springs compress from the centrifugal force, and it cuts down the fuel flow until the RPMs go back down a tad.

 

[Cummins Driver]

But, what makes it pop and miss when you dont have the fuel volume you need? It shouldnt have air or anything in the lines to be injecting?

Eric

 

[97singlecab]

I have the stock fuel system in my truck and 4k rpm springs. mine revs right past 4k never pops or misses ever. Maybe your running out of fuel pressure, clogged filter or something and the low pressure is causing it to pop. Not sure though just a guess.

 

[Cummins Driver]

Im not having the problem now. I had that problem before i put my carter pusher pump on though. Im just wondering what causes it.

Eric

 

[kalder]

I'm guessin w/ low case pressure the plungers can't hit the pop off pressure in the injector till late in the stroke, not starting the burn fast enough, so there is still a combustion event going on w/ the exhaust valve opens. $.02
I'm sure Smokem will chime in and have a better answer!