bad fuel pump?

[omarrakeen]

mmm u dont need a new gas tank...i changed mine ...i didnteven get the gas tank down :P i made a cut in the car body jst above the fuel pump lool its like a fuel pump door now :P

[Super83Z]

Yea 4th gen tanks are plastic they are a popular upgrade for thirdgens.

[Looking Good in Red]

so, i just finished the spark plug, and no problems yet.
but yesterday it did the same thing so im going to keep my fingers crossed.

[theholycow]

Originally Posted by Looking Good in Red

While I was waiting for her to come out of her house, I was just idling in the parking lot and I heard about 5 knocks coming from the gas tank/exhaust area. It literally sounded like someone knocking on it.

I used to have exactly that happen 100% predictably in my 1997 Grand Am. I'd be waiting at the traffic light for the highway on-ramp 5 minutes from home and it would go "tock-ee-tock-ee-tock".

I eventually found out what it was, and have since forgotten.

[Camar0wn3d]

Originally Posted by Looking Good in Red

figures it would come back.
again, today it did the same thing.
seems to be happening only when i give it more than 1/4-1/2 throttle in midrange
this confuzes me, because once it gets over midrange, it doesnt do it anymore

I had the exact same symptoms after doing a plug/wire change on my 02 z28. It turns out it was one of the plug wires was barely contacting my headers (or exhaust manifold if you don't have headers) and the insulation broke down which allowed the current to short to the headers, causing a misfire. It really only did it while the engine was under 2000 RPM but above 1/2 throttle. Seemed to be worse on rainy days or after washing the car. My fix was to tie-wrap the new plug wire to secure it away from the headers.

The best I can tell is that the short didn't take all the current, some of it still went to the plug to create the spark, but when in the high throttle, low rpm condition the ECM called for a richer mixture, which the weakened spark couldn't ignite. However, once above 2000 rpm or so the mix leaned out and ignited, getting rid of the symptom and confusing the hell out of me.

This may not be it, but it's worth a shot. I wasn't able to see the spark shorting to the header until I shut off all the lights in the garage at night. The knocking you're hearing might be the unburned fuel from the misfire igniting in the hot exhaust pipe or muffler, which might also explain the random O2 code you are getting. Good luck!

[Looking Good in Red]

damn, this thing is starting to piss me off.
its back, but even worse now.
it is actually misfiring right now for sure, but it only happens in short intervals and not very often, so at least i dont have to deal with it that often. still isnt pulling a code so no help there
so, i have a theory.
if a spark plug wire is melted and is shorting out, will it pull a code?
as i said earlier, i changed the plugs and wires, and as i was checking for loose wires, i noticed that the wires on the passenger side, i had installed backwards (as in, i put on the heat shield tubey things, but they were on top of the engine, not where the exhaust is, so they are doing no good. my fault, i was in a hurry when i did the wires and didnt pay attention.)
so, im thinking that maybe a wire is too close to the manifold and is melting causing a problem like below...

Originally Posted by Mr_Draco

Sounds like a problem my last car had. It would come and go like that too. It started right after I changed the plugs and wires so figured that had to be the problem. Come to find out it was indeed one of the brand new plug wires. It was broke inside and would only connect sometimes.

or this:

Originally Posted by wh0rsep0wer

I had the exact same symptoms after doing a plug/wire change on my 02 z28. It turns out it was one of the plug wires was barely contacting my headers (or exhaust manifold if you don't have headers) and the insulation broke down which allowed the current to short to the headers, causing a misfire. It really only did it while the engine was under 2000 RPM but above 1/2 throttle. Seemed to be worse on rainy days or after washing the car. My fix was to tie-wrap the new plug wire to secure it away from the headers.

The best I can tell is that the short didn't take all the current, some of it still went to the plug to create the spark, but when in the high throttle, low rpm condition the ECM called for a richer mixture, which the weakened spark couldn't ignite. However, once above 2000 rpm or so the mix leaned out and ignited, getting rid of the symptom and confusing the hell out of me.

This may not be it, but it's worth a shot. I wasn't able to see the spark shorting to the header until I shut off all the lights in the garage at night. The knocking you're hearing might be the unburned fuel from the misfire igniting in the hot exhaust pipe or muffler, which might also explain the random O2 code you are getting. Good luck!

it is doing almost the exact same thing as when my ignition coil went out, but it isnt pulling a code, and it is definitely not happening as often, and the coil did, so im ruling that one out. but im pretty sure it is electrical now, because it isnt happening all the time

[Camar0wn3d]

Mine didn't set a code until about a week after I first noticed it. It set the code after I made it misfire for like 10 seconds continuously, and it actually made the Service Engine Soon light blink a few times, then set the code for the misfire.

In other words, you can have a short on your plug wires without it pulling a code.

I would be willing to bet that your problem is one of those wires on the passenger side that you installed incorrectly. Without the heat shield in the right place it could easily melt the insulation.

You should definitely get new wires and put the wires/heat shield on by the exhaust b/c the manifold gets extremely hot and can melt the insulation real quick. The more it melts, the worse the short. Also, make sure you have plenty of space between the rest of the wire and any hot engine parts. I had to use a tie wrap to get mine clear.

[JJ#48Racing]

Originally Posted by Super83Z

Yea 4th gen tanks are plastic they are a popular upgrade for thirdgens.

Only 99 and up have plastic tanks. He has a 98.

[Looking Good in Red]

Originally Posted by JJ#48Racing

Only 99 and up have plastic tanks. He has a 98.

wait, so if mine is metal, would it be a good idea to swap mine for a plastic one for weight loss?
btw, i'm going to check my wires later today, ill post the outcome when i get done.

[Paperer]

I'm not trying to steal your thread, but is this noise in the video a bad fuel pump? I would hate to make another thread asking the same kind of question.



It stopped a few days later.

[Looking Good in Red]

it definitely doesnt sound good...
not sure what that is
ok, so after I pulled the wires, i did see that two of them had little indentations on them, just like burn marks!
i just bought some new ones for free (warranties are a great concept!!!) and am just waiting for her to cool down so i can fix this thing for good!

thanks all for the help, and i will post if anything else comes up...
if you dont here from me again, either i died or she is feeling alot better

[CamaroSpike23]

Originally Posted by Super83Z

Yea 4th gen tanks are plastic they are a popular upgrade for thirdgens.

not all are plastic

Originally Posted by JJ#48Racing

Only 99 and up have plastic tanks. He has a 98.

Originally Posted by Looking Good in Red

wait, so if mine is metal, would it be a good idea to swap mine for a plastic one for weight loss?
btw, i'm going to check my wires later today, ill post the outcome when i get done.

its not worth pulling the tank to swap to plastic for weight savings alone. however, you could benefit from a plastic tank via not having the posibility of corrosion inside the tank clogging up the filter.

Originally Posted by Looking Good in Red

it definitely doesnt sound good...
not sure what that is
ok, so after I pulled the wires, i did see that two of them had little indentations on them, just like burn marks!
i just bought some new ones for free (warranties are a great concept!!!) and am just waiting for her to cool down so i can fix this thing for good!

thanks all for the help, and i will post if anything else comes up...
if you dont here from me again, either i died or she is feeling alot better

one other thing to do while you are at it is to pull the battery cables or the PCM IGN fuse to reset the pcm

[Super83Z]

Originally Posted by JJ#48Racing

Only 99 and up have plastic tanks. He has a 98.

Oh come on, nobody cares about LT1's and first year LS1's.

[CamaroSpike23]

Originally Posted by Super83Z

Oh come on, nobody cares about LT1's and first year LS1's.

LT1s are the bestest.

and 98 LS1s are the "special" year model....lol