HELP - SW1 fuel pump not running

If you've changed the fuse and the fuel pump relay and the fuel pump will still not run, you're pretty much down to the fuel pump itself. To remove it, you have to drop the fuel tank down from under the car and fuel pump is mounted in the top of the tank. Try and get as much of the gas out of the tank as you can before you lower the tank. The gas weighs 7 lbs per gallon so ten gallons of gas is 70 lbs and is much more difficult to handle. Also, there is a fire danger from gasoline fumes when you open the tank so try and remove the tank outdoors away from the many sources of ignition that exist indoors. The fuel might have failed due to the formation of a lot of gunk around the pump as the gas in the tank aged over the years or it might have failed from water in the bottom of the tank which froze and then the pump was activated or something like that. There's all kinds of stuff that happens with cars that are not driven for an extended length of time.

There should be a connector near where the harness goes to the fuel tank. Disconnect it - you may be able to get to it without dropping the tank. Pull the fuel pump fuse and measure fuel pump current with an ammeter. With the pump disconnected, there should be no current flow. Looking for a short circuit in the harness before you drop the tank...

One question though. Did you replace the fuel filter? If the filter gets plugged, the fuel pump pressure gets very high and can damage the pump or just blow fuses eventually. Any water in the fuel system tends to plug a filter almost immediately. Water molecules are much larger than gasoline molecules and plug the pores in the filter membrane. Pull the filter and let it drain into a glass jar. Look for water droplets. If you can blow through the filter (after it drains) - use a tube to blow through, the filter isn't plugged.

While the filter is out, you can put an extension hose on the fuel line from the tank. Have someone turn the key to the on position. The fuel pump should run for about a second and stop if there are no trigger pulses from the engine (signaling engine rotation). If the pump is still good, you should get some fuel delivery.

If you do wind up replacing the pump, be very careful. Even if you manage to drain or siphon all the fuel out of the tank, the fumes alone are explosive. Remove the negative battery terminal. Remove all connections to the tank and drop the tank. Helps to make a stack of 2x4's cris-crossed under the tank to help let it down slowly. Most of the tanks are plastic these days so sparking is not as big a problem. Back in the day when tanks were all metal, you'd wet down all the joints with something like WD-40 and and use brass tools (drift and mallet) to remove the locking ring that holds the pump into the tank. Brass is non-sparking and is less of a problem for ignition. Back in the day, there was always an access plate to get to the top of the fuel tank under the rear seat. Haven't seen one of those in some time. Don't forget to move your drained fuel far away from the work area and keep a BIG dry chemical or CO2 fire extinguisher close at hand!

That's good advice... but what follows is pure nonsense.

Garbage.

Gasoline is mostly heptane, and a heptane molecule is FAR larger than a water molecule. Water consists of one oxygen atom and two hydrogens. A carbon atom is a bit smaller than an oxygen atom, but heptane has *seven* of them, plus sixteen hydrogens. A water molecule is positively tiny by comparison.

Bulls**t.

He may have a plugged filter -- but it sure as hell isn't plugged with water.

You can't argue with experience though... I had a car that I neglected to change the fuel filter for some time. I had noted that the pump was running noisy and by the time I got a chance to look into the problem, the pump had failed.

Replaced the pump and filter. tried to blow through the old filter and it was plugged up. In most fuel injection systems, the only pressure relief is the fuel pressure regulator on the injector rail. If the fuel lines get plugged, the pump will run at excessively high pressure, draw higher current and either blow the fuse or kill the pump itself.

Had another time with a carbureted car that fuel filter screwed into carb body. Just filled the tank and while going through a bad section of town, the car died. Long story short, I removed the filter and the car started. Found about a pint of water in the gas tank that came with the fill-up.

Prove it to yourself with an old filter. you can blow through it. Rinse water through it and you can't blow through it anymore.

Can't argue with ignorance either, obviously.

After ckecking the obvious and asking for advice here and elsewhere -

I towed the car out of the high grass onto the smooth gravel where I could get under it for inspection and for access to the filter and fuel lines if needed. As reported above, I had earlier changed the battery for a known functional (but older and used) one just in case the battery was part of the problem, but no change. I had also tried both used batteries with my charger connected and after charging for a while.

I always like to enter the winter season with good batteries and at least one good spare ready for use if needed. IMHE batteries that seem to be functioning just fine in the summer will often fail at the first sign of cold and can cause other system damage when they fail. Before really getting serious and tearing anything apart, I thought I should install my newest battery (which I just purchased for another car). BINGO, turned the key, heard the pump then engine started right up and ran perfectly.

I might have dislodged or vibrated something when moving the vehicle or tapping the tank, but I doubt it as the ground was pretty smooth and I did not get too aggressive.

I suspect that this is just another example of -

1 - don't get in a hurry, 2 - consult the manual, and knowledgable others, 3 - think about the problem 4 - do the easiest and most obvious stuff first.

Thanks all here for their input, I will be buying a couple of new batteries as I prepare for winter. The older ones will go into machinery I use mainly in the summer months and do not need to depend on in winter.

Good luck, YMMV

I'm not convinced that you solved the root problem. A vehicle that old invariably develops a bit of oxidation on chassis ground points and sometimes on connector pins. If any of the wire harnesses were abraded - particularly ones exposed to the elements, the wire core itself can corrode and give an intermittent circuit.

True that some cars have very little allowance for low battery voltage while cranking. I believe that the absolute minimum voltage allowable to start the engine while cranking is 8V and probably closer to 9V. A new battery usually does not have as great a voltage drop while cranking.

If it were my car, I would remove the fuel pump relay and bridge it - forcing the pump to run. Assuming that your injectors are not leaking, this should not let any fuel into the intake manifold. Now, go through the entire harness from the fuel pump relay back to the tank and wiggle wires, tap connectors... You should be able to hear the pump running and hear when/if it stops when you touch something.

Don't recall on that car if there is a crank angle sensor (this car doesn't have a distributor??). Either way, something generates timing pulses when the engine is rotating to fire the spark plugs, inject fuel at the right time... If that pulse is intermittent, no starting. About that era, lots of cars had reluctor coils in the distributors to generate the ECU timing pulse. Most common problem an open coil. Remember, no pulse, no spark and no fuel pump. Like I wrote previously, at key on, the pump will run for about a second to prime the system. If there are no timing pulses, the pump shuts off again.

Good luck Oppie (2001 lw300)

I agree with your comment regarding ground connections. My policy has been to always clean (and dielectric grease) ALL ground connections at the FIRST sign of electrical problems or aging and in fact had done this PM on all my Saturns this spring, (including the ground that requires the removal of the battery tray).

In conversation with a Saturn tech last week I was told that in his opinion all Saturn wiring is undersized by a size or two and that he has had to replace several harnesses in his work. In the old days it was common practice to pierce the wiring with a probe when testing for power but this allows moisture to enter the wire and cause corrosion. I would think that this would be even more of a problem with undersized wire.

I am hoping that I have solved my problem but will keep your suggestions in mind if I have continuing problems. Thanks for your input.

Remember that dielectric grease is non-conductive. It will do a good job of sealing any iffy connections against further corrosion. The best connection to ground is with a 'gas tight' connection that bites through any surface insulation. If there is a ground stud, for example. I remove the wires from the stud and put about 10 amps through it while measuring voltage drop with a meter. I have a fixture with an old headlamp which clips to the battery+ and has a long lead for measuring chassis grounds. I've seen a few studs where the chassis connection is poor. Always good to use toothed lock washers (external tooth preferred). I learned the 'gas tight' bit when working on military equipment. The force of the connections keeps any oxygen from the connection and causing corrosion. I usually apply a bit of white grease from a spray can over the ground connections.

Yeah, I hear you about the punctured connections. I always cringed when I saw techs doing that. Happens less now among pros who have access to good computer diagnostic gear. These days everything goes through a computer and can be diagnosed if you have big bucks to buy the equipment. Whenever I have to pierce a wire, I have a syringe of RTV caulk that fills in the hole.

... but what follows is pure nonsense.

(Hangs head in shame) You're right. Don't know what I was thinking. Was ruminating about this old discussion and realized it wasn't molecule size. Rather, when the paper filter membrane absorbs water, it swells and the pores close off making it impermeable. The pores do not appreciably change size in clean fuel.