lower fuel pressure after -8 fuel line install

[tsiawd98]

I was wondering if anybody knew the answer to this who performed -8 line from pump to rail and -6 from fpr back to tank.

I was in afghanistan for a few years and when I got home my fuel in the tank went to hell. I took off the injectors and had them cleaned at a shop over here where I live. I then removed the fuel tank removed all fuel. I chose to add -8 a/n fuel line from the pump to the rail, and from the other side of the rail -6 all the way back to the tank. I researched the forum and got the job done.

Today, I finally put some gas back in the car and fired it up. after cranking for quite some time it started.A nd is running good at idle. however, my aem wideband is now showing 17.8 at idle. and 38-39 psi on the fuel pressure regulator. I have a supra pump in there that I used to dyno with years ago. I do remember that the fuel pressure used to be 43 psi at idle and and had 14.7 on the wideband. I had the car tuned years ago at ums in arizona by Tony with a AEM EMS.

I am asking for a answer until I get back on the dyno because the car is going to be down for a while. If I should just raise the fuel pressure back up to 43 psi on the regulator? and will that bring my air fuel ratio back to a normal level? Any advice by people that have done the bigger fuel lines? I am lost right now and have tried to find a similar answer on the web.

 

[dustyboner]

was the fuel pump your using the same one that had been in the tank with the old gas? if it was did you change the filter on the pump and also the fuel filter between the pump and the rail?
if you haven't i would change the filters first.
just going to an 8AN feed shouldn't lower your fuel pressure. the regulator will open the bypass (return) at the same pressure unless you mess with the adjustment.
what kind of regulator are you using? on an aeromotive (maybe others too) its possible the ball isn't sealing completely.

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going from 43 psi to 38 psi will be like decreasing the injector size by about 6%.
unless your tune has closed loop disabled, the ecu should adjust fuel with the o2 input and bump up the fuel trim to compensate for the lower fuel pressure.

 

[tsiawd98]

I have been using the supra pump now for 10 years, same pump. I have 950cc injectors. Everything from the top of the tank to the rail is new. new fuel filter also. I have not checked yet, if fuel pressure changes with vacuum line disconnected. I will check tomorrow. I do not have a closed loop system as I am running a standalone ems. I have not changed any fuel values at all. the wideband o2 sensor does not adjust for fuel trim at all, It just reads what air fuel ratio you are at and tells you on the guage. The o2 sensor is the aem wideband uego, and I bought a new one a few months ago. Could it go bad in a couple of months? Maybe, anything is possible. I forgot to add, that yes while everything was out I did replace the fuel strainer on the pump with a new one from Toyota.

 

[dustyboner]

i haven't messed with an AEM for years, i have been tuning honda k motors with hondata for so long that i don't remember what options are on other systems.

your setup looks solid, i would just bump your fuel pressure back up and see if it takes care of the problem.