1996 Lumina 3.1 fuel filter

[conflag98]

Two quick questions. Does this car have another fuel filter besides the one that runs near the rail on the driver's side? Also, is there a fuel pump cut off switch on it? The fuel pump is doing its thing, and just to make sure I put in a brand new relay. Car now starts barely then dies. At one point it ran for about a minute, then choked off and died. I appreciate any help.

[funkbox80]

The fuel filter is along the fuel lines under the car, it is a round cylinder that is connected by 2 little clips ( careful tho when u disconnect the fuel filter, it holds a fair amount of gas) so have something ready to catch the gas or at least don't get it in your eyes.

[funkbox80]

There's probly a fuse you can take out to stop the fuel pump, far as I know there isn't a switch for it.

[Tech II]

That is the only filter.....

There is no cut off switch.......

Have you checked fuel pressure? There is a schraeder valve on the fuel rail to check pressure....

Can try spraying carb cleaner into the intake while someone cranks the car.....if it runs as long as you spray, you have a fuel problem......either lack of pressure or an injector problem....

[conflag98]

Yeah, I didn't think I would get that lucky lol. The owner said that it failed to start for him, so he thought of the fuel filter and went to change it. I guess he didn't use any PB or anything and promptly twisted the line where it has a 180 degree curve in it just after the outlet side. That sounded pretty cut and dried to me. I sprayed starting fluid into the TB and it started and ran for a moment. I was just going to bypass the twist with some rubber fuel line to get it to start and then go from there. I bought a new filter and a short piece of line with a fitting on the end. I quickly found out that the aftermarket line does not work in the outlet side. Even when fully tightened the line has play and will spray gas. It lacks the lip that fits into the opening inside of the outlet that the factory one has. I took the piece of old line w/ the lip off the old filter and put it on there and that seemed to work, but the car still wouldn't start unless prompted with starting fluid. When I turned the key on I couldn't hear the fuel pump kick on, BUT I am working on a very busy road and it is hard to hear anything. I found the fuel pump plug under the car, took it loose from the frame and shoved it up into the trunk where I could get to it. I applied power to it and still couldn't hear it, but again, busy road and lots of noise so I wasn't sure. I dropped the tank, took the dang thing out and applied power, it kicked on and shot out what gas was in the pump. When I reinstalled the tank I replaced all the lines coming into or out of it besides the filler tube line and the actual fuel lines, which appeared to be in good shape. I also put a new relay in. Still no start without starting fluid. I went back to the trunk, applied power back to the pump, and I could hear it run. (nightime, less traffic) I repeated this a few times, turning the pump on and off. I put a spray of fluid in it, it fired right up and ran great for awhile. (it did stumble at idle and felt like it was going to die but didn't, then that evened out) It then sputtered out. Now it just will not start at all, though it is trying. I did notice some leakage around the outlet of the filter so I redid the rubber line and stopped that, but still no start. I don't know exactly what preesure the line is holding, but it's enough to spray several feet into the driveway when disconnected. Any ideas?

[jeffcoslacker]

I'd be wondering about the pump...they can do that, work intermittently, seem to deliver good volume unloaded but fall on their face under pressure.

The quickest way your gonna figure this out is with a fuel pressure gauge, any other way will just be guessing...you MAY be able to do the rent-a-tool from AZ or another parts store...

You'd wanna see somewhere in the 36-42 psi range at the rail I think...can't remember spec on these but that seems right. They'll run all the way down to only 10-12 psi I've found, but not well and starve out and die after a short time.

If it needs a pump, I'd strongly recommend getting a GM pump...I've seen a lotta problems lately with Airtex, what most places sell, especially on older GM's like these...don't know what the problem is, but I'm sure not gonna do that job twice if I don't have to.

Normal fuel hose will NOT withstand injection pump pressure for long. If you still have that questionable patch you might wanna re-do it. If you need to replace a section of the steel line, you can get what's called a compression fitting that will form a union between two sections of metal line...very easy to use. You'll need a small tubing cutter if you're not already using one, needs a clean cut. The comp fitting will have an outer fitting, and a little metal "bead" that goes over the line ends, then screw the fitting together TIGHT. The little bead will form a leak-proof union.

There's an o-ring suppose to be on the end of that line where it goes into the filter. Did you have it? They'll leak without it.

If you have to bend a new piece of line, wrap it around something round in a vice like a junk pulley or whatever...helps keep it from kinking as it bends.

If you can't do a comp fitting, next option would be to rent a line flaring tool (or sometimes you can find one cheap, I paid $9 for mine), put a flare on the lines where you patched, and use a high burst strength hydraulic hose the correct size. Then double clamp the ends of the hose, screws facing in opposite directions on opposite sides of the hose end. That should be a lasting repair.

But my feeling is that this person's fuel pump went out, and all the rest of this is just distraction. You need to verify what kind of pressure it's delivering when it cuts out.

[conflag98]

Thanks for the reply. I have a friend with a gauge in the town I'm working in so I'll check that right out. I have room for the comp fitting, but the 180 degree bend that it would take to re-attach to the other end might be kinda hard to do. I do have an actual pipe bender so I'll give it a try. As far as that O-ring I wondered about that also. There was none in the box and the guy said it didn't have one. I saw what looked like the remains of fabric or cork on the old line when I took it off, which is what prompted me to ask the guy at the parts place about a seal. I'll check again. Thanks for the help and I'll check pressure first. Where is the port located on the rail, if you don't mind me asking? I looked all over and didn't see one. Does the top part of the engine that covers the injector have to be removed to get to it?

[Schurkey]

Originally Posted by Tech II

That is the only filter...

Well, that and the mesh pre-filter on the inlet of the fuel pump.

[Tech II]

Schurkey, you are correct.......the "sock" should be replaced with a new pump(I am not dropping a tank to just replace a sock, though)......unbelieveable, the amount of techs who just transfer it to a new pump.....

[jeffcoslacker]

Originally Posted by conflag98

Where is the port located on the rail, if you don't mind me asking? I looked all over and didn't see one. Does the top part of the engine that covers the injector have to be removed to get to it?

I should know this, but I'm tired as hell. I believe unless I'm dreaming that you can see it if you look under the upper intake from the passenger's side. You should be able to access it pretty easily. I'll go look and make sure in the morning. Mine is '97, should be the same.

[jeffcoslacker]

Yeah OK, here's your rail, as seen from the passenger's side and front. You can see the port on the rear rail's end. It should have a cover cap on it.

[conflag98]

I really appreciate the information. I am now thinkng that it's the pump, or a piece of it anyway. Why I was stupid enough to drop that whole tank without at least THINKING of changing that sock-looking filter, or for that matter the whole pump, is beyond me. I guess I'll chalk it up to inexperience and the heat, but I've heard about this sock and should have spent the few bucks on it while I had the tank out checking the pump. I'm going back over today and work on it and take it from there, but I feel pretty sure I'll be doing a pump today. Thanks for all your help and the time it took you to give it. These forums have helped me tremendously on different cars and I'm glad you pros have the patience to mess with us dummies lol. Thanks again!

[Blue Bowtie]

Verify the voltage at the pump. A few resistive connections in the harness can drop the pump operating voltage to the point where it cannot make adequate pressure.

[Schurkey]

Originally Posted by conflag98

I've heard about this sock and should have spent the few bucks on it while I had the tank out checking the pump. I'm going back over today and work on it and take it from there, but I feel pretty sure I'll be doing a pump today.

If the sock is actually plugged enough to cause driveability problems, the tank needs to be emptied and cleaned--or replaced if internally rusted.

Grit contamination of the fuel is a leading cause of fuel pump failure.

Originally Posted by Blue Bowtie

Verify the voltage at the pump. A few resistive connections in the harness can drop the pump operating voltage to the point where it cannot make adequate pressure.

Absolutely. There's a dozen places (or more...) for corrosion to build up and create voltage drop.

VOLTAGE should be measured as close to the actual pump as practical--at the connector closest to the harness leading into the sending unit. Measure voltage WITH THE PUMP RUNNING. A voltage test with the pump not running is completely invalid. You'll want to see within one volt (less difference is better) of the voltage at the battery. The wire harness on the sending unit--inside the gas tank--is a known and common problem for many GM vehicles. New fuel pumps often come with replacement wires for the sending unit harness. Be sure to inspect the sending unit harness visually and with an ohmmeter.

AMPERAGE can be measured most anywhere in the circuit; if it's convenient to measure it at the same place you're checking voltage, that'll be just fine. Typical fuel pump amperage draw is 6 or 7 amps.

Best solution is to use an oscilloscope with a low-amps probe--but few people have access to one. See post #2:
http://www.thirdgen.org/techboard/tb...p-upgrade.html

[conflag98]

Well, the pump worked. The vehicle starts right up, and though a little rough at idle runs OK. Here's to doing one job three times!!!! (I 'forgot' to mention that when I first put the tank back in, got it all bolted up and stuff, I suddenly couldn't remember if I had pushed in the fuel lines on top until they clicked! Being old and brain-dead I couldn't recall, so I had to drop it again to check. Good thing too. I hadn't.) I appreciate all the help everyone has given me. I have never taken a gas tank out of a car, but I knew if I got in a bind I had a place to go. Have a great day!