92 3.3 turns over but won't fire?

[mavrick]

1992 Pontiac Grand Am won't start. 3.3L V6 auto.

Drove it to work this morning, nothing unusual happened on the way. Car ran fine, was responsive to the throttle while fighting through traffic, and was just like any other day.

After work, got in, turned the key, and it just turned over and over without firing at all. No sputter, no try, nothing but the starter churning away at the flywheel. Popped the hood, looked around, checked coils, wires, plugs, wiring harnesses, nothing looks out of place or feels loose.

Continuing to turn it over with the hood open and even pump the gas, there is still no firing at all, and no smell of fuel to indicate flooding. I do not hear the fuel pump buzz when the ignition is initially turned on, but does it actually buzz every time, or only when the computer thinks it needs to prime the cylinders?

I'm not sure where to find the fuel filter on this car, but I found a silver cylinder (like an old-school steel filter or perhaps a pressure regulator?) attached to the rear fuel rail (closest to the windshield), and unscrewed the coupler there and pulled it back to see if it would spray any fuel(*), and it did not, even when pumping the gas pedal.

There is no PassLock on this car, and the 10-min test didn't work. The coils have been replaced in the last year, and the wires are new. I searched around in several other threads and wonder if it could be a relay (does the fuel pump actually run off of a relay?), or a fuse under the hood somewhere?

Personally, I think it is the fuel pump. But, I am no mechanic, so I ask if anyone has seen this before and can suggest some other things to check before it has to go in to a shop? If the pump is in-tank, I have an estimate at around $500 to change it out, and $270 or so for the pump alone. What is so special about an electric fuel pump that makes it that pricey?



*DISCLAIMER* - if you are silly enough to disconnect a fuel line, please don't stand in front of it to see what will happen when you crank over the engine. Pressurized fuel can spray very unpredictably, and if you don't have safety goggles on, it will hurt like hell. Stay out of harm's way, and if things look wet when you stop turning it over, then there is pressure there, and never use a lighter in place of a flashlight.

[GTP Dad]

Welcome to AF! Unfortunately, I believe you have a fuel pump problem. If you don't hear the fuel pump then chances are the fuel pump has gone out especially if you have spark. A way to see if the pump is out is to depress the shrader fitting on the fuel rail, if fuel squirts out then the pump is working, if not the pump is gone. I always have people try this, take a can of starting fluid and spray a small amount into the throttle body. If the engine starts the fuel pump is out.

Before replacing the pump, check the fuse and relay but I would bet money that the pump is dead!

[4terryc]

Originally Posted by GTP Dad

Welcome to AF! Unfortunately, I believe you have a fuel pump problem. If you don't hear the fuel pump then chances are the fuel pump has gone out especially if you have spark. A way to see if the pump is out is to depress the shrader fitting on the fuel rail, if fuel squirts out then the pump is working, if not the pump is gone. I always have people try this, take a can of starting fluid and spray a small amount into the throttle body. If the engine starts the fuel pump is out.

Before replacing the pump, check the fuse and relay but I would bet money that the pump is dead!

Additional diagnostics. These cars have a work around circuit to limp you home if you have a fuel pump relay failure.On my 93 3.3 there is an oil pressure switch located below the oil filter, (access via the rt frt wheel well) that continues to provide power to the fuel pump until the oil pressure drops. I guess this gives you a defence against getting stranded or losing power at speed.
I had the opposite experience when this switch went bad on the highway. It made a dead short and blew the fuel pump fuse. To diagnose unplug the fuel tank connector over the rear axle and if it continues to blow fuses this oil pressure switch is suspect. Credit where credit is due..... the gm shop manual for this car is awesome and will only refer you to the scan tool when a test light won't do.