Fuel tank vent valve and fuel pressure sensor locations.
05-15-2008, 12:14 PM
#11
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What are your thoughts about the engineering logic that went into this system. Under no circumstance should full engine vac pressure be aloud to be drawn on the gas tank. The tank could explode and result in a fatality.
The system has an engineering defect IMO.
I've already spent 6 weeks trying to fix this. When it gets stuck in this diagnostic mode, I brought it to Autozone and there were no codes in the computer.
The only code that is stored is if I loosen up the gas cap.
I appreciate your reply, but give me some credit here..........
The system has an engineering defect IMO.
I've already spent 6 weeks trying to fix this. When it gets stuck in this diagnostic mode, I brought it to Autozone and there were no codes in the computer.
The only code that is stored is if I loosen up the gas cap.
I appreciate your reply, but give me some credit here..........
05-15-2008, 12:53 PM
#12
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OK, credit where it is due. 
However, I guess I'd have to question your choice as to how to resolve your issue, correctly that is. You have identified that the system is staying stuck in diagnostic mode and that this is attributable to either the PCM, the pressure sensor, or the vent valve. More than likely, it is the sensor or the valve, located on the fuel pump.
Now, if your New York car has the same corrosion issues that my '97 did after just three winters in Michigan, there very well is a corrolation to be seen. The location of the fuel pump and sender unit is such that mud and salt easily can get up there without being easily washed off.
It is not too big a project to get to the fuel pump and sender unit. Replacing what you find bad there (if that is indeed the problem) is certainly a proper way to address an issue like this, unless you are convinced that it is your PCM, in which case I would have expected to see other problems too and not just this single one.
My concern lies very much in that you are intending to apply a bandage to the problem. One that will preclude your seeing advance notice of other problems as they pop up. While it is certainly your choice what you do, you did ask for advice and this is it, in my opinion anyway. 
However, I guess I'd have to question your choice as to how to resolve your issue, correctly that is. You have identified that the system is staying stuck in diagnostic mode and that this is attributable to either the PCM, the pressure sensor, or the vent valve. More than likely, it is the sensor or the valve, located on the fuel pump.
Now, if your New York car has the same corrosion issues that my '97 did after just three winters in Michigan, there very well is a corrolation to be seen. The location of the fuel pump and sender unit is such that mud and salt easily can get up there without being easily washed off.
It is not too big a project to get to the fuel pump and sender unit. Replacing what you find bad there (if that is indeed the problem) is certainly a proper way to address an issue like this, unless you are convinced that it is your PCM, in which case I would have expected to see other problems too and not just this single one.
My concern lies very much in that you are intending to apply a bandage to the problem. One that will preclude your seeing advance notice of other problems as they pop up. While it is certainly your choice what you do, you did ask for advice and this is it, in my opinion anyway.
05-15-2008, 01:58 PM
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I replaced the gas tank and sending unit last year with brand new parts. Right you are, it was rusted to a crisp.
I replaced the canister vent valve, purge valve, vacuum lines, gas cap.
Checked electrical connections.
Just down to the FTP sensor on top of gas tank, and I'll have to drop the tank.
It can't be the vent valve at the gas tank because I can pump gas into the tank with no problem.
It can't be a clogged charcoal cannister because I checked the operation and it is clear.
So yes, the bandaid approach is looking attractive at this point. Because The FTP is another $40.00 and a replacement PCM is even yet more money.......
I replaced the canister vent valve, purge valve, vacuum lines, gas cap.
Checked electrical connections.
Just down to the FTP sensor on top of gas tank, and I'll have to drop the tank.
It can't be the vent valve at the gas tank because I can pump gas into the tank with no problem.
It can't be a clogged charcoal cannister because I checked the operation and it is clear.
So yes, the bandaid approach is looking attractive at this point. Because The FTP is another $40.00 and a replacement PCM is even yet more money.......
05-15-2008, 02:50 PM
#14
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Hmmmm...Ok, it certainly looks like you've given this plenty of consideration. Maybe you could see about the possibility of purchasing a re-flashed PCM from somewhere like INTENSE. There'* are much less costly (quite reasonable IMO) than a GM replacement and you could add or change some parameters at the same time if you wanted.
05-15-2008, 03:32 PM
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I appreciate the interest you and others have shown.
I read over the intense website and very reasonable cost, especially if you send a core in.
What I'm thinking though is maybe having the PCM thats in the car now reflashed maybe the cure.
Couldn't this be done at a local repair shop?
I did alot of work on this car recently and have disconnected the battery many times. It could be that the computer got corrupted from one too many on/off cycles.
I read over the intense website and very reasonable cost, especially if you send a core in.
What I'm thinking though is maybe having the PCM thats in the car now reflashed maybe the cure.
Couldn't this be done at a local repair shop?
I did alot of work on this car recently and have disconnected the battery many times. It could be that the computer got corrupted from one too many on/off cycles.
05-16-2008, 09:46 AM
#16
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My answers in bold.
Originally Posted by reb
I appreciate the interest you and others have shown.
Lol, that'* what we do here at BC.
I read over the intense website and very reasonable cost, especially if you send a core in.
I believe that they will also refund if you send the core back afterwards, but you would have to check with them on that.
What I'm thinking though is maybe having the PCM thats in the car now reflashed maybe the cure. Couldn't this be done at a local repair shop?
It depends upon whether they have the correct codes from GM, I believe. In otherwords, I don't know for sure.
Lol, that'* what we do here at BC.
I read over the intense website and very reasonable cost, especially if you send a core in.
I believe that they will also refund if you send the core back afterwards, but you would have to check with them on that.
What I'm thinking though is maybe having the PCM thats in the car now reflashed maybe the cure. Couldn't this be done at a local repair shop?
It depends upon whether they have the correct codes from GM, I believe. In otherwords, I don't know for sure.
05-18-2008, 08:21 AM
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A member sent me a pic of a new gas tank outside of car. The FTP plugs into the small round hole located in the recessed area on top of tank. To the left of the large hole for the sending unit.
Its been 175 miles since the PCM reset, and the vac problem has not come back yet. So, I'm not going to replace the FTP until it happens again.
That whats so frustrating about this issue.........
Its been 175 miles since the PCM reset, and the vac problem has not come back yet. So, I'm not going to replace the FTP until it happens again.
That whats so frustrating about this issue.........
11-14-2011, 03:20 PM
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reb, you originally asked how to solve your problem. You received some good information and even indicated that you realize what your problem is. The answer to how to properly fix your problem lies in following the test sequence posted on Monday by SSEBONNE4EVA, just above. He didn't just post that article to give you something to read, he actually gave you the information you need to correctly diagnose it yourself.
By choosing to ignore the good information he posted, you are indicating that you are looking for some excuse not to do the right thing, IMO. Just disconnecting the system and then ignoring the DTC light is NOT how to fix this problem. A proper diagnostic sequence, as posted, and then repair or replacement according to what you find is the correct fix.
Remember that we are only able to see what you write and post and are not there to actual do the diagnostics and repairs for you. If you choose not to do the diagnostics that are recommended and report your findings back to us, then there is no possible way short of guessing, and being wildly lucky, that we can help you with a correct fix.
So PLEASE. If you do want to really fix your problem and insure that it stays fixed, do the diagnostics as indicated and get back with us. If you have need of a scanner, there is always your local parts store or perhaps even a nearby member may have a scanner. In any case, realize that there is no magic here and that the information we give you is only good if you actually use it and follow the advice.
By choosing to ignore the good information he posted, you are indicating that you are looking for some excuse not to do the right thing, IMO. Just disconnecting the system and then ignoring the DTC light is NOT how to fix this problem. A proper diagnostic sequence, as posted, and then repair or replacement according to what you find is the correct fix.
Remember that we are only able to see what you write and post and are not there to actual do the diagnostics and repairs for you. If you choose not to do the diagnostics that are recommended and report your findings back to us, then there is no possible way short of guessing, and being wildly lucky, that we can help you with a correct fix.
So PLEASE. If you do want to really fix your problem and insure that it stays fixed, do the diagnostics as indicated and get back with us. If you have need of a scanner, there is always your local parts store or perhaps even a nearby member may have a scanner. In any case, realize that there is no magic here and that the information we give you is only good if you actually use it and follow the advice.
If your not even going to try the information you get from the site, for a question you ask, why even bother being a member?
My hat is off to you, as for REB, why ask questions if you not even going to try the advice you recieved?