I have a 98 Firebird 3.8, 5 speed 105,000 miles as a DD. The fuel pump failed but pumped enough to let me drive about 15 mph for a few miles before it died totally.
I put a new pump in it and it starts right up now but does pretty much the same thing. It won't run past 1500 RPM and if you go to wide open throttle it will slowly bog out and die.
What I have done and know:
No codes
42 psi of fuel pressure and it holds it for 5+ minutes after shut off.
Fuel pressure regulator was new 5,000 miles ago
Tried a new ignition module no change
Replaced the fuel filter but it was fine.
Pulled 5 of the 6 plugs after revving till it dies and they are not wet with fuel and no sign of anti freeze



Plugs and wires were new 2 years ago at 80,000 miles
Timing does advance from 10 to 30 when I tach it up.
Compression in #1 is 145 and I can't really get to the rest of them.

It runs a lot better with the oil filler cap off so I'm concerned there might be some mechanical damage in it?

I picked up a spark tester and will check for good spark tonight but I am stumped on what the problem could be. Any help would be appreciated.

 

Those plugs are bad. The insulator (the white part where the electrode protrudes) should be a golden brown/bronze color indicating the car is running normal. Chances are with the dying fuel pump, the plugs suffered the same fate. Can't hurt to change them any ways.

What's the pressure if you move the throttle 1500 rpms or above?

 

Thank YOU! I'll pick up a set of plugs and check the fuel pressure with it tached up as far as it will go tonight and report back.

 

i would look at the 02 sensors as well. when they foul they can give false readings that cause a rich condition. also reset your computer and sensors. unhook both battery cables from the battery. hold the cables together for a minute while not hooked to any power. unhook any amps or capacitors. grounding will reset all your computerized sensors and clear your main computer. it may take a few starts and runs to allow the computer to adjust.

 

I did have the battery unhooked for 2 days to do the fuel pump but never heard of touching them together.






I have considered that the 02s may be cooked from running very lean for a few miles but I don't think they are key to the issue here. As I understand the system on cold start it looks at temp, MAP and throttle position to give a static fuel mix to get it running. The 02 sensor is not in play at that point untill it warms up enough to talk to the computer. The car runs just as bad on first start as it does when it's warm.

 

Check this out guys.

 

Sounds like the Cat is plugged.

 

yep i agree, open up the exhaust before the cat and see what happens.

 

Well the cat guys win the prize! It was welded on but had to cut the pipe to find out and sure enough it tached right up and had all the power it had before. Why driving 15 miles with low fuel pressure killed the cat is beyond me but sure glad it's running again. THANK YOU THANK YOU THANK YOU!!!