97Ej6mike

Its been awhile since ive last posted on here, but here goes..

I currently am having an issue with my 97 civic LX (JDM D15b swap (3 stage) running with VAFC and P2E (y8) ecu) thats keeping me from passing inspection, based on readiness sensors.

I am throwing 2 codes that i keep clearing (OBDii scantool)
p0450
p0453

Fuel tank pressue sensor and fuel tank high output.

My question is.. Where or what on my year civic measures fuel tank pressure? To be honest, in all my years of working on hondas (even as a tech at honda) ive never seen nor heard of this issue. My first thought was my gas cap, but i checked that and it checks out fine, there is a sufficient amount of airflow "wooshing" when i open it after the tank has been sealed, so ive ruled that out. Then, I thought perhaps it was a reversed evap solenoid or wrongly routed evap purge hoses. Checked those, those check out to be fine. Keep in mind, the car passed just fine back 2 years ago, and nothing significant has changed since other than regular maintenance.

I was hoping someone may be able to shed some light on this issue, because it is preventing me from passing inspection. I keep clearing the codes, but then only 4 of 7 readiness sensors are ready (5 is the minimum in NJ), until a few drive cycles later when the checklight pops back on again( usually 2 or 3 days) , at which point it reads for 6 of 7 readiness sensors ready, but you cant have a check light on to go through.

This is somewhat frustrating to me, and im not sure where to start.

THanks in advance to anyone who can assist me on this.

Matt55

well, you could see how much fuel pressure you have so you can see if the sensor is bad, or you actually have high fuel press

Matt55

or the fuel pressure regulator could be bad itself

speedooo

I bet it has something to do with your routing of your vac lines

97Ej6mike

Well it comes up as a general Fuel pressure sensor failure, the exact code is "high voltage". My main question is... On a 1997 civic LX sedan, where exactly is this Fuel pressure sensor located? To be honest, ( not to sound ignorant or stupid) , in all my years of working on honda's, i was completely unaware there was even a sensor specifically for the fuel pressure. I thought that fuel pressure (tank pressure at least) was measured by way of the vaccum in the EVAP system. All i was aware of there being was a bobber (to determine amount of fuel) and the pump located in the tank. Is there also a pressure sensor in there as well?

Matt55

the fpr is on the fuel rail, idk exactly on a civic

97Ej6mike

Yes, thats true, the FPR is located on the fuel rail, but it is not an electronic device, just a vaccum run one. And as far as i know, it seems to be working just fine. At least from my experience, if that item is not running correctly (clogged vaccum line or even a leak), one's gas milage would see a significant decline. Im averageing 28 to 32 miles per gallon upon each fillup, which is normal.
Im confused about what sensor actually reads the fuel pressure, and then determines whether or not it is too high or low, or is just malfunctioning altogather.

nub

Here's link with a DIY fix http://www.ff-squad.com/technet/code91.htm Only certain model Civic and Integra have a FPS and and the ecu you're using is looking for it. The sensor itself is mounted on the fuel tank, drivers side, upper left corner. I have a mini-me running on a P2E and have the same issue as far as the cel. If I remember right the DIY involves adding a potentiometer to a particular ecu pin to feed the required voltage. This only worked for me for a couple days and the cel came back on. After checking into it further I found that the ECU expects some fluctuation in volage which the mod. doesn't allow. The only real fix I've come across is to use a ODB2A P28 from a 96 DelSol (hard to find).

rick_rabies

the big black can....rip it out. the fuel vapor line is prolly clogged

speedooo

Which line is the vapor line? The canister is supposed to have 1 line to the evap purge solenoid, 1 to the tb and 1 towards the gas tank...correct? His evap purge solenoid is routed to the nipple on the top of the tb...pretty sure that's an issue.

I'm pretty sure his car is equipped with this sensor since he's been running this motor setup for almost 4 yrs and the cel is just coming on.

roycivic92

change the gas cap also

rick_rabies

if your gas tank vapor drain is clogged you are harboring a time bomb

its the metal line that comes up from the back of the car up the firewall then its a rubber hose from that to the black can. rip that whole can out and cap the vacuum on the motor. bend your gas tank vapor line down and unplug your sensor on it. you dont need it.....you dont neeeeeed itttttt unless you live in CA.

nub

My bad, I guess I missed that this is a new problem to an old set up. The LX with California emissions has the pres. sensor on the tank. http://www.hondaautomotiveparts.com/...L+TANK+%282%29

97Ej6mike

Thanks for the info there, but i dont beleive that will help me if it came on in a few days. See.. when i clear the code with my scanner, it comes back on in about 2-3 days... This is when the readiness sensors set for that particular system. So that doesnt really solve my issue. It was never an issue until now, and it passed just fine last time.



This is true. Please keep in mind... The car, with the exact same setup, passed CEL free with all 7 readiness sensors ready in spetember of 2007. I have never had an issue. This is something that isnt affecting its driveability in the least bit.

Like i said before, the gas cap likely isnt the issue, it makes a very tight seal, and it makes a loud "woosh" when opened at any time, whether i just put the car in accessory and primed the pump, or after 250+ highway miles commuting to school when i fill up.

Former User

97Ej6mike

Oh wow! Thanks ron!

Thats definitley a big step in the right direction for me!

Where did you get such a guide from?

I used to work for honda, and had infinite access to an insane amount of info and guides just like that, but it wasnt an issue for me then, and i no longer work there, so i dont have access to such things anymore.

Again i thank you, that is def a big help. Now to find where this fuel pressure sensor actually is.... lol.