pgm02002

I cannot get the truck to run smoothly between 3000 and 4000 rpms under full throttle. My timing is around 16 degrees, should it be higher? the exhaust cleans up mostly and my fuel pressure doesnt drop?? please help. it sound like it is skipping. lower rpms run great.

pgm02002

the boost is up close to 70 psi

kawi600

If your fuel pressure isnt dropping I doubt youre having fuel starvation. Youd see the pressure drop as the fuel going out to the injectors passed the amount going in and created a drop on that side of the overflow valve. I had this for awhile, it was a restrictive fuel valve in my case. I have an aux fueling system.
The mechanical setup usually sees 26-40 psi or so depending on conditions. If youve set the pump to keep the pressure up you should be ok.
What about adjusting the governor springs a little?
Fueling is what drives the heat to make boost, so I dont think youre low on fueling. if youre able to push 70 psi on a ported head thats a lot of flow.
You might also look into some better injectors. You can probably clear up some of the low end / idle smoke with some DDP, F1, etc.

pgm02002

do you notice a difference with 19* as opposed to like 16 or 17*?

Jambbii

I could pull my fp down to 0. With similar mods and bigger injectors. I have been running my aeromotive pump for a while with no issues.


Josh

kawi600

Ooops, just noticed youre running a separate fuel pump, not the mechanical one on the block.
Ive never used one.. but I think theyre good as long as you match the flow rate to the application. You might need something larger, you didnt specify what rating the pump is. Airdog comes in different ratings like FASS, right? 95, 150, etc.?
I know racor has a chart saying 400hp needs something like 80gph. Youre probably up into the mid-600's with that kind of boost? But thats just in filter flow capacity, not necessarily pump flow. Someone else that knows the rule-of-thumb for hp / fuel volume should hopefully chime in.

pgm02002

its the new 165 gph

BigErksG2

are you on a stock HG with your studs? I would run more timing.

pgm02002

yea, i got it at cummins when i did the head