I'm just now getting around to caring about this issue because it seems to be keeping me from making more power. Any time you snap the throttle, it has a single stumble right when it hits idle speed. If you throttle up by hand to about 1k rpms and let off it seems to dip below idle speed for a second and come back to a steady idle. Ive searched and cant find this info, I know I've had it before and read about it on here. I must be missing it when I look.

So VE Pump guru's, what causes this stumble returning to idle and a top end lack of fueling?????

 

Do you have a fuel pressure gauge? Sounds to me more like the opposite issue, it's loading up when you snap the throttle.

 

What size injectors and H&R?

On my phone so I cannot see sigs.

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14mm hr 5x16 injectors, fp a steady 15+psi.

 

I need to just take a video and post it on youtube tomorrow.

 

You might be sucking the VE dry, sootforbrains had this issue a while back.

Have you done any transfer pump work to the VE yet? Case pressure guage?

 

Its not a lack of fuel problem, with no load and just 1krpms there is no way its starving. Even under WOT I havent seen it drop below 12psi ever.

I'll take a video of it later and post it up. Load and rpm doesnt change the stumble as it returns to idle rpm.

 

I read it has something to do with the fuel being back washed, I've seen some guys say it kills the truck on really hard throttle then letting out to nothing. As I remember there is nothing you can do about it besides change your driving habbits. It seems its worse for 14mm pumps with big injectors.

 

You may have 12-15 psi At the transfer pump but it is possible to drain the case quicker than the transfer pump can fill or keep up.

 

Im not talking about hard runs, it does this even when you lightly idle it up to 1krpms and let the throttle drop back down. There is no way the case pressure drops with no load and only 1,000rpms. Its reving in neutral, there is no load, boost, or fuel demand.

 

If i had to guess its because you are fueling more and it takes less throttle movement so when you snap the throttle shut it goes from 1k to idle faster than it did on a stock truck and it falls slightly lower before it can catch back up, My truck with fairly stock settings and stock injectors acted normal, but once i put the 3800 spring and maxed out the fuel screw and messed with the afc, it will dip when you snap the throttle,but i also think my idle might be a hundred rpm low also if any of that makes sense....Does in my head lol..

 

You might be on to something here. Mine does the same (probably not as bad as yours) with the 3200 spring. It might dip 100rpm below idle and come back up.

 

What is your idle set at? How far do you have the pump turned up? This really has me stumped. If I get a chance I will ask my pump guy tomorrow. I need to ask him some questions anyways. Leaving for San Antonio Sunday morning.

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