I got a check engine light with the code 91, Fuel Tank Pressure Sensor.
Does anyone know how to fix this? Any help would be appreciated. Thank you


[Modified by JeffNA, 3:57 PM 4/4/2003]

 

Have you tried re-tightening your gas cap?

 

I did but nothing happened....

 

Try resetting the computer afterwards by either pulling the ECU fuse in the engine compartment or the negative terminal.

Do you tend to overfill the gas?
I heard that sometimes this messes uo the pressure sensor??

 

I'll try to reset the computer. The CEL code went off when I spliced the radio harness. I'm not sure that was the cause. I never overfilled the tank but the car is on empty for the past month since it was garaged and never used.

 

I have the same problem.. There are two versions of it according to my helms

P0452 - Fuel Tank Pressure Sensor Low Input
P0453 - Fuel Tank Pressure Sensor High Input

I have P0453.. It turned on immediately after my alarm was installed and the "fuel cutoff" was tested... they didn't fix anything though so i'm stuck with the code.

I've followed all of the instructions accord to helms do diagnose it, and i've done all but the second step (I believe) which is to check the voltage on a P3 Connector right by the fuel tank/fuel pump..

I ripped out everything from the inside of my car just to realize I can only get to it from the bottom of the car I think I have to take out the f'ing fuel tank just to check the voltage on some connector

If anyone else has this problem please post any information you've got... I don't have the $$ to take it to Acura @ $85/hour right now.

thank you!!

 

By any chance did you switch from obd2 to obd 1 and disconnect the purge vavle? I think that might do something with it. Alldata says check all vacuum hoses for leaks and /or clogs. I'll send you the procedure if you want

 

I'll check my hoses again. Thanks for the info

 

OBD1 ecus dont check the tank pressure sensor

 

You usually get this code when you switch from OBD2a to OBD2b.

If that's the case, the OBD2b ecu looks for a sensor on the fuel tank that doesn't exist on the OBD2a cars.

 

i got this code too. just did a b20z, obd2 ls ecu in a 96 civic. all was good for a while, then started it up a couple days later, and that was it. i havent really messed with it yet, but im gonna check it out. ill let you know what i find.

 

I have Code 90 and have no idea how to fix it either.
Tried the whole gas tank cap thing and reset the ECU - light came back on in 2 days.

I do top off the gas all the time though. Prevents coming back to the gas station all the time.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RealTypeR &raquo;</TD></TR><TR><TD CLASS="quote">I have Code 90 and have no idea how to fix it either.
Tried the whole gas tank cap thing and reset the ECU - light came back on in 2 days.

I do top off the gas all the time though. Prevents coming back to the gas station all the time.</TD></TR></TABLE>

thats EXACTLY what i have. i dont think its a big prob though, car still runs great and gets great mileage

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SilverB18C1 &raquo;</TD></TR><TR><TD CLASS="quote">

thats EXACTLY what i have. i dont think its a big prob though, car still runs great and gets great mileage </TD></TR></TABLE>


your avatar...casey rox!

btw, have you guys tried swapping gas caps?

 

I pressure tested mine on our emissions analyzer at work. It seems fine.

 

my mom's car threw that code and she tightened her gas cap, but that didn't help. after she bought a new cap, it got rid of the code. my mom has a 2002 4runner, but try that. good luck.

 

i might try that anyway. the only things i can come up with before going through the Helms troubleshooting are:

My evap purge vacuum line tees to a reducer to a very small vacuum line to the back of the Sk2 manifold.

The fuel pressure is set at 50psi. Higher than what it used to be with the DX engine.

My entire evap system components are the original dx parts, except for the teed reducer.

I think I am going to try and leave the evap vacuum to the manifold disconnected while pluggin the vacuum on the manifold and see if that same code comes back. I almost feel like there is a restriction there, maybe it can't purge everything from the canister....sigh...mine comes on within hours after resetting the ecu.........
any other ideas?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Soup **** &raquo;</TD></TR><TR><TD CLASS="quote">


your avatar...casey rox!

btw, have you guys tried swapping gas caps?</TD></TR></TABLE>

damn right casey rawks!

ill try getting a new gas cap, that could be it since, when ever i unscrew the cap i dont hear any pressure being released.

my CEL comes back after about 2 days of driving.

 

Ok I did some tinkering. If you have the high pressure code, I doubt that a new gas cap or tightening would fix your problem. If the cap was faulty or loose, there wouldn't be high pressure there I imagine.

Anyway, I have a SK2 IM and one thing that I did was tee the evap to a reducer to plug in to that tiny vacuum nipple on the backside of the manifold. I was thinking there might be a restriction "backing" up the venting process, leaving high pressure in the tank. So I plugged the manifold and left the evap hose loose. Reset the ECU and now I don't get the code anymore (2 days driving). So in my case I guess this is the problem. What I'll probably end up doing for a permanent fix is capping the smaller vacuum line on the manifold and teeing to the brake booster nipple since its the same diameter. Hopefully this will work.

 

bah, spoke too soon! fuel tank pressure high came back last night....................................

could this have something to do with upping fuel pressure??

 

Evap sucks. I hate doing function tests with the Honda PGM tester. It takes forever. And it's such crap...take the gas cap off....put it on....take it off...put you hands on hips and cluck like a chicken...energize the purge solenoid. Argh. It has helped me a couple of times though. I'm not sure if the function tests are available for your car though. Mostly accords, oddyseys, and hybrids. Anyway, it all sucks. Sorry, had to vent.

 

will converting to OBD1 fix this?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SilverB18C1 &raquo;</TD></TR><TR><TD CLASS="quote">will converting to OBD1 fix this?</TD></TR></TABLE>

Yes, converting to obd1 will fix this. Also for the people who have 96-98 civic with obd2 swap, you'll need an EX gas tank or weld the sensor in(kinda dangerous), and a charcol canister with a purge solinoid on it. Wire everthing up and you should be good to go. Oh yeah and it does not mess with the a/f ratios or timing so power is the same

 

sweet, i think id rather spend the money to convert to obd1 then try and figure this stupid problem out

 

Good idea. Evap+OBD II= CRAP