View Full Version : Fuel pump/ pressure ? Inside


BadAzz96Z28
07-07-2006, 10:42 AM
I have a walbro 255 inline pump w/stock intank pump and need some advice on this. When I installed the inline 2 years ago I did what was recommended by a sponsor here and tied the pump into the wire harness that feeds the stock pump as well.

My concern is that with this setup at idle I am at 50psi and WOT it runs around 42psi. Could this be b/c of the way it is wired up and not getting enough voltage to feed the 2 pumps on the stock wires? If so I guess that it would be good to run a seperate circuit for the inline pump and see if I get my fuel pressure back up a bit.

How much would getting the fuel pressure back up change the car as far as AFR, power, fuel inj. duty cycle? Im just wondering now b/c I am finished with my TNT nitrous kit and if n/a pressure dips to 42psi then it will drop more on the spray.

AFR with the current set-up is 13.0 and injector duty cycle is at 94%

Thanks for the advice in advance and sorry for the long post

Nasty N8
07-07-2006, 11:47 AM
What kinda power are you running? The stock pump is barely good to 400-430rwhp. Adding the inline pump is a patch and will not supply any more volume just help keep the pressure up when demand is high. If your pressure is already droppng that far you have a problem. It will certianly help to add a dedicated wiring to the pumps to feed more voltage but I would rec. adding an intank Walbro pump as well to get your pressures where they should be 58PSI. And is your TNT kit wet or dry? If dry you will need to up your injectors as well.

Nate

BadAzz96Z28
07-07-2006, 11:58 AM
415/385 n/a at 13.0 AFR and 94% inj duty cycle.....I am running a wet/dry combo kit with 100 wet TNT and 50 dry.......juiced it made XXX/XXX w/11.8 AFR and 106% inj. duth cycle.....I didnt watch F/P on the dyno was looking at KR and timming with hp tuners

Nasty N8
07-07-2006, 12:04 PM
You are very lucky with that setup being on the raged edge that you have not hurt the motor yet. I would up the injectors, Hotwire the pump and add an intank pump for sure. One small extra dip in pressure and you will burn a piston. On the street your demands are slightly higher than on the dyno also.

Nate

BadAzz96Z28
07-07-2006, 12:09 PM
I was planning on upping the injectors and was just wondering about doing a racetronic in tank or just rewire my inline and see if that helps.....any power gains getting my fp up to 58psi over what it is now?

Nasty N8
07-07-2006, 12:14 PM
I rec. you do both just for safety. I do not think your power will go up as your fuel ratio was safe but it will be way more stable.

Nate

BadAzz96Z28
07-07-2006, 12:17 PM
Thanks for the input.....would you run just the racetronic in tank or get that one and leave the inline since it is already on?

Nasty N8
07-07-2006, 12:25 PM
It won't hurt anything to leave the inline one there.

Nate

BadAzz96Z28
07-07-2006, 12:36 PM
Thanks man......