Isis fuel pressure regulator issue.

[Mfabsr20]

I am having an issue with my sr. I installed a z32 maf, 750cc injectors, rs enthalpy rom tune, and an isis fuel pressure regulator. When I start the car initially to warm up, everything is fine. When I disconnect the vacuum line from the isis regulator, the car actually seems to idle better. When I plug the vacuum line back into the regulator, at the appropriate fuel pressure, the car get really lopey, uneven, then dies out. Could the problem be with a faulty regulator, or could I have vacuum leak somewhere like the wastegate etc. In the process of trying to diagnose my problems I redid all of my vacuum lines. Again on initial start up everything was cool, until I tried to adjust fuel pressure. Any help would be appreciated. Thank you

[Croustibat]

why am i not surprised to read "isis" and "issue" in the same sentence ?

bin that crap, install oem one, problem solved.

[jr_ss]

bin that crap, install oem one, problem solved.

Or install a quality FPR, not knock off cheap shit. Sard, Tomei, Nismo, aeromotive, etc.

[Mfabsr20]

please correct me if i am wrong but the oem fuel pressure reg can't handle 750cc injectors.

[beems240sx]

increase the fuel pressure to 55psi so the fuel atonomises better.

see if that helps.

or call ken at enjuku and im sure they will exchange it

[Mfabsr20]

I have an rs enthalpy tune, and I contacted Martin who did the tune. He said increase pressure to 50psi. So I did. Still no success. I then increased it more to 60 to see if that helped. Same deal there. Just dies out every time. I know there aren't any other serious issues b/c previous to the injector and fuel reg install my car ran fine.

[Croustibat]

please correct me if i am wrong but the oem fuel pressure reg can't handle 750cc injectors.

Tell that to my 1000ccs injectors.

[Croustibat]

increase the fuel pressure to 55psi so the fuel atonomises better.


Or dont. Because then the fuel pump has to work at 55psi + boost and still provide enough flow. Which it probably wont, resulting in ... yes, reduced pressure.

How about just using what works, like the OEM FPR ?

[Mfabsr20]

I did that also. I would lower fuel pressure in increments trying to find that "sweet spot". Thinking that I would be out matching the fuel pump. The same would happen, the car starts to sputter then die. After going over my engine a few more times, I am starting to believe the isis fuel pressure regulator is just crap.

[Croustibat]

Isis is rebranded chinese crap, so yes, thats basically it.

A quality FPR is worth at the very least 80$, which is why i went cheap and kept the oem FPR :D As long as it works, no reason to change it.

[Mfabsr20]

Tell that to my 1000ccs injectors.

Croustibat,For your 1000s what size fuel pump are you using?

[Croustibat]

i use a walbro 255L/H high pressure. Fuel is e85 so i have more fuel needs than regular gas.

[4x4le]

Get a fuel pressure gauge in your car or at least hook up a temporary trouble shooting one (usually can be rented at parts store for a deposit) and actually diagnose it.

You should be at 43.5 psi at no vac, 43.5 psi - vac, and 1lb of fuel pressure for every lb of boost.

This is the reason you shouldnt skimp out on any part of your fuel system.

AND this is why you need a good tuner and why you shouldnt go with canned tunes.
I have an rs enthalpy tune, and I contacted Martin who did the tune. He said increase pressure to 50psi. So I did. Still no success. I then increased it more to 60 to see if that helped. Same deal there. Just dies out every time. I know there aren't any other serious issues b/c previous to the injector and fuel reg install my car ran fine.


The truth is, until you have a build consisting of nothing but quality parts and a good tuner tunes your car or you spend allot of time with it yourself, there are always going to be things like this to complain about.

[[email protected]]

I am having an issue with my sr. I installed a z32 maf, 750cc injectors, rs enthalpy rom tune, and an isis fuel pressure regulator. When I start the car initially to warm up, everything is fine. When I disconnect the vacuum line from the isis regulator, the car actually seems to idle better. When I plug the vacuum line back into the regulator, at the appropriate fuel pressure, the car get really lopey, uneven, then dies out. Could the problem be with a faulty regulator, or could I have vacuum leak somewhere like the wastegate etc. In the process of trying to diagnose my problems I redid all of my vacuum lines. Again on initial start up everything was cool, until I tried to adjust fuel pressure. Any help would be appreciated. Thank you


If you purchased the FPR from us i will more than happy to exchange it for another one so you could eliminate the issue if its the FPR.

Phone-352-241-8399

[Mfabsr20]

If you purchased the FPR from us i will more than happy to exchange it for another one so you could eliminate the issue if its the FPR.

Phone-352-241-8399

Giuseppe, I did purchase it from you guys. I actually spoke to Wesley @ enjuku over the phone yesterday, and wrote him a detailed email explaining my issues and if I could exchange the isis unit for a aeromotive regulator and I would pay the difference. I have yet to receive an answer, he said he would check to see if that would be possible. Thank you for your help

[[email protected]]

Giuseppe, I did purchase it from you guys. I actually spoke to Wesley @ enjuku over the phone yesterday, and wrote him a detailed email explaining my issues and if I could exchange the isis unit for a aeromotive regulator and I would pay the difference. I have yet to receive an answer, he said he would check to see if that would be possible. Thank you for your help

Ill take care of this,please email me or give me a call so we can get you the new FPR ASAP.

[email protected]

352-241-8399 ask for me.

[4x4le]

What everyone is witnessing is that if you are going to buy less than grade A name brand parts, isis from enjuku IS the way to go because they do stand behind their parts. Not all of their stuff is Chinese, it is from whatever manufacture meets their need for the product they are wanting to offer.

Many of the Japanese brands have some of their products made in china too....

With all that said I am still pretty selective with my fuel system.