Hey guys,
This is my first post on this forum, and I'm sorry to pester you guys but I could sure use some assistance. I'm at home with my old carbureted V8's, but this 95 Cavalier of my wife's is a whole different ballgame.

Her "check engine light" has been coming on for years. It has been through a couple true problems, such as bad wires and bad plugs, both of which were no big deal to diagnose and fix.

A couple weeks ago, I was driving it to work (it burns a lot less gas than my pickup) and I noticed it hesitating when near full throttle. On the way home that night, I didn't even get a mile before it flat died while I was pulling away from the parking lot. It sputtered a couple times while trying to restart it, but it would not start. I called a tow truck (I don't have a trailer) and the guy I usually have do work I really don't want to do (front strut work, etc) picked it up for me. He added more gas (it was showing about 1/8 tank left) and it started right up for him. I don't think he tried to start it before adding gas.

My wife noticed it hesitating on the drive back from the repair shop, but she didn't know that's the same symptoms I noticed before it completely quit. She filled up the tank on the way home.

I tried driving it to work the next day, and it made it to work OK that morning, although the hesitation at higher throttle was much more noticable. It was definitely associated with higher throttle levels, as it idled just fine and ran OK at moderate throttle levels.

On the way home, it was drivable still but the hesitation got progressively worse, until it almost wouldn't run at all- it would idle, but little more. It never backfires, coughs, or misfires- it just goes or it doesn't.

I'm suspicious that the fuel pump is giving up the ghost, but before I spend $260 on a new one I want to know with certainty that this is the problem. The car isn't in bad shape, but I'm not willing to just buy parts and swap them out unless it's the right part. The car just isn't worth that much.

I borrowed a kit-built OBD-2 cable that a friend made to scan codes with a laptop PC and tried it, but I couldn't get it to work. I get nothing but "busy signal" when I try to use it, and I suspect it is either a problem with the laptop (Dell is kind of notorious for non-standard USB and serial ports, or it could be an XP issue I guess) or something similar. I've been told that 1995 was produced before GM became completely compliant with the OBD-2 standard so it may not work. Here's a picture of the connector if it helps:



So, is there a way I can determine for certain that the fuel pump is (or is not) the problem? It doesn't feel like an ignition problem for sure, but of course ignition modules can fail in the strangest ways. I'd sure like to know for sure if it's the fuel pump before spending that much on it.

Surely someone knows how to troubleshoot this???

First of all, this should have been posted in the Maintainance Forum, but I'll help you anyways.

Those are the exact same symptoms my car gave me, just before my fuel pump went out. You can do a free flow and pressure chek of the pump, but that may or may not help. The CEL you keep getting is probably a random cylinder misfire, since the pump is not flowing to capacity and not getting sufficiant fuel. The reason it works, when it does, is the winding are wareing out and building more resistance and they get hot. When they get hotter, they increase resistance and get hotter, till the pump shuts off.

The easiest check for this, is when you turn the ignition switch to the run position you should hear the pump run for a few seconds. If you do this after the pump has shut down, you wont hear the pump. To verify this, use a volt meter and see if the voltage is getting to the pump. Goto the underside of the rear of the car and find the wiring harness to the fuel pump. Connect the comman (black) lead to a good ground or the pinout to the black wire to the pump. Connect the positive (red) lead to the pinout with the grey wire and have someone turn the ingnition to run. You should read approximately 12 volts DC. If so, then the pump is bad. If not, then you have an electrical problem, somewhere else.