Exotic-metal55

I replaced my stock high pressure pump with a bosch 044 .. This pump in conjunction with a high flow intank pump should flow for 600 plus rwhp on paper..


Made a few test runs and still have a large pressure drop above 5K.. This pump seems about the same as the stock pump.. I focussed more on psi drop vs trying to graph the exact psi to rpm change.. I did not see psi go below 65 psi this time and it seemed to hold 70 psi out longer. Either way, 78-79 psi is normal and I am still seeing a 10-15 psi drop above 5000k..


1)Any I deas?
2) Anyone check thier pressure on stock or light moded cars?
3) Maybe AMG drops pressure for more volume? Just a wild guess.Need to know what a stock psi shows.

I am stuck right now and not sure what to try next.. It is hard for me to see that 5-6mm ID fuels lines are not a potential flow issue..



Here is the pump , before i fastened down and insulated it..

sneakyneon

try splitting the ground and ground the pumps seperate so the ecu cant control them (if the ecu does control the ground side???)

splinter

Just for diagnostic purposes, have a go with the filler cap ajar.
It’s a (albeit remote) possibility that the unburned hydrocarbon recovery system is inhibiting sufficient flow.
Sure as hell has tripped me up previously - quite like a finger over the soda straw.

gOt BoOsT

the bosh 044 should be producing way more psi than that. try upgrading the fuel pressure regulator...or maybe the intank pump.

gOt BoOsT

actually since the bosch is installed inline the restriction is the intank pump for sure...not the regulator. gL

sneakyneon

how much noise dose your pump make?

Exotic-metal55

Do you know if the ECU controls the pump through the ground or just for test purposes?

Stock regualtor is set for 80 psi and I assume I would need to fix the PSI drop before raising pressure?


I can not hear any pump noise at all.. If I just turn the key on and have the shroud cover off, then I can hear it pressure up .. This is very slight and only for a second.. Are yours noisy?



Here is a pic of the stock bosch 044 outlet fitting (brass color) that was removed , in place of a 5/16 barb fitting.. Any ideas how to use this fitting again or add a ball valve back to the pump?






It is 98 deg. outside and I made some hwy runs checking 02 Mv.. From 4K up, I hold a solid .945 MV.. Not a great test but very safe MV.. Timing is 19 but drops to 9 deg. when IAT`s hit 140 deg.

I also have trouble with starting after the car sits.. It seems that removing the Bosch 044 outlet fitting , eliminates the ball valve? Any ideas on adding a ball valve back, to keep pressure from bleeding off?