carsonau

Hi Guys, I have a Code 91 (Fuel Tank Pressure Sensor low input) on my 97 Acura 1.6EL (same engine as the 97 Civic SI D16y8), what should I be looking for?

This happens right after I replaced the Intake Manifold, could something be put in wrong or lose?

I have tried reseting the ECU, it usually goes away for a while, but it will come back if the engine is off for a few hours.

Thanks for your help!
Cars

_Cyclone_

Hello fellow EL driver and fellow Canadian! I actually just had the intake manifold off in my EL this past weekend, and that makes me think of a couple things. First off, make sure both hoses that lead into the EVAP purge control solenoid on top of the fuel rail are both firmly connected, and make sure that solenoid is plugged in. Second, make sure your fuel return hose is tightened down well enough. Change the OEM honda scissor clamp with a real hose clamp for that one, and make sure it's good and tight. (Mine was leaking and throwing a code at one point before I converted to OBD1) I replaced it with a real hose clamp and the problem went away.

carsonau

Thank you so much, this is extreamly helpful, I will check that tomorrow and will report back! BTW, are u on clubel?

_Cyclone_

I used to visit from time to time, but the majority of that crowd is newbs.

carsonau

Not having any luck so far...
I could not see any leaks anywhere in the fuel system... so I went to a garage near by, they checked for leaks using a smoke machine and said that there is no leak...

They wiped the code for me and drove fine all day yesteday, but then the code comes back this morning again, it seems to happen overnight, somehow the pressure is relieved overnight.

I also found out the exact code , it is a P0453 Fuel Tank Pressure (FTP) Sensor Circuit High Voltage.

Any other suggestions would be great!

carsonau

More info I found about P0453

P0453 - FTP Sensor Circuit High Voltage Detected The PCM monitors the EVAP control system FTP sensor input signal to the PCM. The test fails when the signal average jumps above a minimum allowable calibrated parameter. FTP circuit open
VREF shorted to VPWR
Damaged PCM
FTP circuit shorted to VREF or VPWR
SIG RTN circuit open
Damaged FTP sensor
FTP V PID reading greater than 4.50 volts with key ON and engine OFF or during any engine operating mode indicates a hard fault.

_Cyclone_

So it's a high voltage fault then... that changes things. This now indicates a faulty sensor, or a wiring problem. Best thing to check first is the last suggestion in your last post.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by carsonau &raquo;</TD></TR><TR><TD CLASS="quote">FTP V PID reading greater than 4.50 volts with key ON and engine OFF or during any engine operating mode indicates a hard fault. </TD></TR></TABLE>

Use your multimeter (if you don't have one, now's the time to get one) to check the voltage of the wires leading to the sensor while the key is off. This can be trickey because you will have to read the voltage of the wires without disconnecting the sensor, meaning you will have to strip some of the coating off the wires to check. If the above condition is met, replace the sensor. If not, let me know in this thread... be sure to keep this thread up to date with your latest findings.

carsonau

Thanks again for your help, I finally broke down (after posting and trying things from 3 different forum) and went to some shops...

First local garage shop, charged me 2 hours and said it was fixed, turns out they only reset the ECU and it came back the next day

Second shop was the Acura Dealer, charged me 1 hour to tell me they can not fix my car because it does not have a stock ECU.

Third shop (garagefive.net) was amazing, they know within a min I walked in. Turns out there is no gas tank sensor in the EL, but there is one on the Civic SI (where the ECU was from). I could try to look for a ECU from a single cam vtec with no gts but then who knows what else might come up, so I took the more expensive optiion and went with OBD1 and after that it was all fine.