srt4 problems with my fuel system any help?? - SRT Forums

ace8386 · 10-26-2009, 10:35 PM

i in installed a walbro fp with returline and a set of rc 750's. these injectors are rated up to 530hp.for some reason i am maxing out these injectors while only making 407whp?? the fuel regulator is set at 60 psi? there is no reason why my injectors should be working at 105%. i should be able to up the boost and still have plenty more fuel left?? people are telling me to buy bigger injectors but that cant be the problem it has to be something else???

RiVal · 10-26-2009, 10:42 PM

i beilve 60 psi is to much for a walbro to handle.. u do the bottleneckfix ?? and rewire?

porksword · 10-26-2009, 10:53 PM

You should'nt be out of injector. Do you have the boost reference hooked up on the FPR? If you do then you need to lower fuel pressure about 10-15 psi. If you dont have it hooked up then you should hook it up.

like said before, do the rewire as well.

ace8386 · 10-27-2009, 02:52 PM

no luck with a rewire and a srt4 stock fuel pressure is 58psi so 60 pretty damn close. My fuel pressure seems fine its just my injectors at at 105% duty. im about to just buy a set of rc 1000 and see if i have better luck since i have an aem ems. idk anyone have any other helpful info or ideas?

duster360 · 10-27-2009, 04:08 PM

Its real simple, You need to check the fuel pressure at WOT at the fuel rail.
I doubt it is what you assume it is.

RiVal · 10-27-2009, 04:58 PM

58 static(stock) is diff that 1:1 boost source.. so 60psi on ur FPR using boost source might be killing ur walbro bro.

Racerxvsspeedracer · 10-28-2009, 02:08 AM

Quote: Originally Posted by ace8386

no luck with a rewire and a srt4 stock fuel pressure is 58psi so 60 pretty damn close. My fuel pressure seems fine its just my injectors at at 105% duty. im about to just buy a set of rc 1000 and see if i have better luck since i have an aem ems. idk anyone have any other helpful info or ideas?

If you are using an areoforce scan gauge to get your IDC of 105% forget about it. That fucker lies Idc is off and so is EGT's.

I had this happen to me it sucked, I was so focused on the IDC and maxing the injectors out. til I found out it was way off and to not tune by it.

The best easy way to know if your injectors are maxed out is what fuel pressure you're running. The higher the fp the more fuel you get til the injectors can't give no more and are stuck open @100%.

1. If your @60psi with a 1-1 and your a/f is under 12 with the boost you want to run then you're fine. It means your rich and have enough fuel.

2. But if your a/f is lean past 12's and the fp is past 60psi with a 1-1 then you need more injector.
Hope that makes sense,
Sean

porksword · 10-28-2009, 11:01 PM

Quote: Originally Posted by ace8386

no luck with a rewire and a srt4 stock fuel pressure is 58psi so 60 pretty damn close. My fuel pressure seems fine its just my injectors at at 105% duty. im about to just buy a set of rc 1000 and see if i have better luck since i have an aem ems. idk anyone have any other helpful info or ideas?

You didnt really answer the question. Do you have the boost reference hooked up on the FPR? If you do then you need to lower fuel pressure about 10-15 psi. If you dont have it hooked up then you should hook it up.

If you have it at 60psi and boost say 25psi then you are ending up with 85psi FP which is a little high.

GreaseMonkey69 · 10-29-2009, 01:02 AM

just like porksword and everyone else said. is your fuel system set up for just a static fuel pressure set up? or does your system have a 1:1 boost regulated fuel pressure??

if your static is at 60 psi your fuel at idle is 1046 cc of fuel. that would be plenty of fuel. alot of guys here have their fuel system set up with boost regulated fuel pressure. 43 psi is what most guys set up their static fuel pressure. using a boost source to increase pressure lets say 20 psi of boost. your 750cc injectors (rated at 43psi) add 20 psi this is 63 psi at WOT which calculates to 1098cc of fuel.

60 psi base fuel pressure 1046cc of fuel then add 20 psi is 80 psi about 1395cc of fuel. at that point those injectors would be maxxed out.

GreaseMonkey69 · 10-29-2009, 01:13 AM

also using 60psi base fuel pressure then running boost regulated fuel pressure up to 80psi and higher your going to kill your pump eventually.

i would go a pump re-wire. it is amazing and you get better life out of your pump and overall performance of the pump.