Maybe this car will be worth all the trouble and expense eventually, and prove to be dependable affordable transportation. I tried today to remove the fuel line connections from the fuel filter. The front one came off easily. The other two, no way! The little square push buttons that have to be depressed harder than my arthritic fingers will allow, were the problem. I tried to make a tool to depress those buttons out of a small C clamp, and then needle nose pliers. No success. Autozone had no tool to do this. On the phenomenon of the leaking pressure internally for the pump. The original pump that was in the car when I bought it did the same thing. It bugged me bad so I Purchased a new pump and had it installed. What a disappointment that it did not fix that problem. I paid a mechanic who I trust, a former neighbor, to install the new pump. That pump is still under warranty, but I dread telling the mechanic the bad news.

I will try again tomorrow to remove the fuel lines from the fuel filter

 

The quick disconnect tool for fuel lines and such is available at any auto parts store. Not saying you are lying, I am saying the person who told you that at the store had no clue what they were talking about.


You take the raised rounded end and insert it under the clips. I believe you only need 3/8.

What brand of fuel pump are you using? Please tell me it is not airtex.

​​​​​​Also, did he replace just the pump or the entire pump with housing and sending unit? I do not know where this check valve would be. Whether it is internal to the pump itself or if it is part of the rest of the housing. I bring this up because it is possible that we are seeing the same behavior as before because this check valve maybe outside the pump and if only the pump was changed, you'd get exactly what we have here today.

That is a total guess. Or that the problem lies elsewhere. We really need to know how all of that pressure is bleeding off. Directly back into the pump or through the return line.

Somebody will be stopping by hopefully to review this thread and hopefully will be able to fill in the gaps.

Aside from a fuel disconnect tool, please do not go out and buy anything.

 

I only read the first part of your post last night because I thought your reply about the availability of fuel line tools is all there was, And fatigue was taking me over. I see now that I was wrong. I did see those plastic tools that you pictured, but I couldn't see how they would work with those push buttons that I spoke of. Finally this morning at O'Reilly I found a pair of fuel line quick connect pliers that worked perfectly to get the bleed-off port connector removed. With key on I definitely had a good flow out of that port. If I owned a diagnostic fuel pressure gauge I would put it on the fuel rail right now and see what it says with that pressure bleeding off into the bucket, but I don't have the gauge and will have to go get it. Up to now, I've been testing pressure in the auto store parking lot.

I also don't know of a way to check to see if the return fuel line to the tank is blocked or not. I could destroy this old fuel filter and use that piece of pipe from the return port, Connect that piece to the return fuel line, put a hose on it and see if I can get the tank to take pressure that way.

The fuel pump is a Delphi complete unit, but if it proves to have failed with the check valve that holds pressure, I won't go back to AutoZone to get another one like it, but will demand an outright refund or trade for a new Carter brand pump Assembly, unless you suggest otherwise. The Autozone manager already told me he will honor returning the pump for another one, but will not pay anything toward the installation costs. I stopped by the shop where the mechanic that installed the fuel pump is, but he was too busy today to look at anything, but he knows something is up, a problem. I think he will be reasonable whatever needs to be done from here on.

With the new fuel filter unit that I bought yesterday I have tried blowing and sucking on the different ports to identify which is which, and the return port will not allow my breath to move through in either direction. If the preset pressure is 50 something, my lungs can't get near that. I won't install that new filter, unless you say to.

 

Well, if you have the key on and fuel is flowing out of the regulator filter return line, that would explain why the pressure goes to 80 while priming then immediately bleeds to zero when the pump is not pumping. It is all pouring out the regulator return line. This would also vindicate the fuel pump as the source of the quote unquote check valve issue.

You can see the fuel pouring out of that module summer it should not be back flowing to.

Chances are that the previous fuel pump may not have been the issue either, and that the issue is with the regulator filter assembly. Other than doing the test you just performed, I don't know how else you would determine between the two. As for the high pressure at the rail, that would seemingly also be related to regulator failure. Which may in fact be leading to the filter regular return line draining all the fuel from the front of the car.

​​​​​​The fact that the pressure is bleeding off and you see gas flowing during your test but see no gas leaking out anywhere when everything is connected up, my assumption, right or wrong, is that the fuel is in fact flying back to the tank.

Since you have already purchased it, try swapping out the filter regulator module. You will have to cycle the key from off to on, listen for the hum and the click of the fuel pump relay turning off. You will need to do this four or five times before cranking as you need to push all of the fuel back to the front of the vehicle and displace the air that is in there from opening the system. Sometimes the hum will be at a certain pitch and when the system gets fully primed the pitch drops slightly. That is how you know you are primed. Since you will need a fuel pressure gauge to verify proper pressure up front, I would go to one of the other stores and do a loan a tool from them.

Once the pressure is down, the mixture should go back to normal provided you unmodify the ects wiring, as that temperature reading plays a large part in the fuel mix as well.

As for oxygen sensor replacement in the front, if it was me I would put a new one, a denso in there because the one that has been sitting in there has been seeing huge amounts of concentrated exhaust. These things to get fouled after about 125,000 miles. They also get fouled in situations like this and then don't respond properly and you guessed it, screw up the air fuel mixture. Or you could operate on the it's not broken so don't fix it principle. If you do, check your gas mileage. If it has dropped a significantly and put in a new denso up front.

If all of this in this post is correct, I am surprised that the person who did the work did not check the fuel pressure with the vehicle running. The bleed off usually points to the fuel pump but with these differently configured regulators I guess that's not the only answer anymore. But seeing 91 PSI at the rail likely would have triggered all the troubleshooting we just did.

Don't know your relationship with him but if it ends up being a fuel pump that you didn't need that you paid labor for.... Then again you'll never know if the fuel pump was also defective so you should probably just leave it alone, hopefully this fixes it, and enjoy driving the vehicle. I know I am getting way ahead of myself and the work to be done, but it all seems to be falling into place as far as logic goes.

Borrow the gauge, swap the module, and post back.

 

I already picked up the diagnostic fuel pressure gauge earlier today and made sure it is the one I used the other day. I will plan to switch out the fuel filter assembly tomorrow, and then monitor the fuel pressure at the injector rail again as before.

Our weather temperature dropped dramatically today from upper 60s yesterday; upper 40s today. With that major change the idle speed has been cooperating pretty well except for one time when it didn't want to come down from about 1700 for Maybe one minute. The rest of the day it has been idling well.

I'll plan to get back to you by tomorrow afternoon.

 

High fuel pressure is the reason for your codes. Your o2 sensor is reading correctly. I had a pressure regulator stick and did the same thing. Your regulator is part of the filter, change the filter and recheck your system pressure. If it is still high remove the fuel cap and see if there is a change. The evap system may be holding pressure in the tank. You may have a pinched return line between the filter and the tank also. The p0132 code refers to high voltage and since your car has a one wire sensor it can only be rich exhaust.

 

First thing this morning I jacked the car up disconnected the fuel return line from the filter. Then working at the fuel rail, I hooked up the diagnostic fuel gauge and discovered right away that it would not register any pressure. I had walked away from Autozone with the wrong gauge!

Try #2; taking another round trip to Autozone and getting all components configured as before, I found that when I first turn the ignition on, psi at fuel rail struggles at 10 to 15 psi before pressure drops to zero. Turn ignition off and right back on, psi at rail builds in about two seconds to 81 psi and shuts back immediately to approximately zero psi

At this point, about 1 cup of fuel has been dropped into the catch bowl on the floor below the filter. I dump the caught fuel out. Now crank the engine, and after a long period of cranking (approx. 2-3 sec). The engine fires and immediately psi at fuel rail jumps to 92 psi and stays there as long as the engine is allowed to run at idle.

Meanwhile, back at the catch bowl, gas is filling it fast, so that 2 quarts are produced in about one minute!

QUESTION: If that much flow is coming out of the relief side of the filter (Normally back to the tank) and the psi at the fuel rail is maxed at 92 psi and never drops even a pound, what more could the regulator do to reduce pressure at the fuel rail?

PROPOSED NEXT TEST:

Cut relief port pipe from old filter and quick connect it to the fuel line returning to the tank. Put a hose on the open end of that pipe and see if there is freedom to blow into the tank through that jury rigged assembly. I will try to do that tomorrow morning. Then I will have no choice, but to install the new Autozone filter.

What ever the results of this test are, there's another problem somewhere obviously, because a theoretical plugged line to the tank is not why the pressure stays at 92 psi on the fuel rail, when the relief port is dropping into the bowl on the floor flowing freely at a fast rate!

On a positive note, with temps up to 70° today, the car has run as good as ever, good idle good power no noticeable misses,BUT I know that the fuel system has a disease!

STAY TUNED! What fun!

 

Designed system pressure is 40 psi, the delphi pump has maximum of 80 psi. What pump did you install? You may have the wrong pump in the car.

 

I will check on the pump model and compatibility with a 2001 SL1, but it's hard to imagine that Autozone, nationwide company, would have the wrong pump listed for my car so that one of their stores would sell me the wrong part.

 

The manager at the Autozone store says I bought a Delphi pump model number DFG0916 rated for 26 gallons per hour. He went on to say that there is a Delphi pump model number S3951M rated at 21 gallons per hour that would put out a lower psi, for same price. Experimentation is not at all appropriate when it comes to the labor involved to switch out one of these pumps!

When I said that it's very concerning that there's no definitive way to be assured I got the right pump, he said that GM changes their specs from time to time, perhaps to discourage aftermarket part production, so that this kind of thing happens, to the consternation of their competitors And those competitors' customers.

Now what? I'm gonna go ahead and do the flow back-to-the-tank check that I mentioned in my last post and then install the new Autozone filter and report back with results.