Fuel Pump Failing?

**Camaro98Z/28** · 03-18-2009, 01:07 PM

So today I was out with a friend enjoying the great weather with the ttops off and auto-xing on backroads by my house.
About 5 mins from home the car I realize almost dies on me.
I bring it home park it and it dies in my drive.
I try to start it, it cranks and cranks but when l pump the gas, it fires up.
So okay I'm thinking maybe I flooded it?!?! So i get it running and idling but its irradical and sounds like the darn thing has a cam in it.
I left it be ran the codes and got P0300 random misfire.
Shut it down came back about 3hrs later fire it up and same thing runs like a raped ape when I'm on it but anything below 1k its like it wants to die.
No vacuum leaks at all.
I put new acdelco irr plugs and wires in about 1-1.5k miles ago.
The other day I was driving it and it acted like this but i romped on it and it seemed to clear out and drove the rest of the day just fine.
Also on the same day it did this I herd a strange whirling noise that sounded like an air pump was mounted above my muffler (hence what further makes me think its a fuel pump)

**Phantom2kz** · 03-18-2009, 02:44 PM

when was the last time you changed your fuel filter?
time to do a fuel pressure test

**Camaro98Z/28** · 03-18-2009, 04:35 PM

umm bought it with 104k
has 106k on it now
nah never changed the filter in the 2k i owned it
but i suppose i should start there

**0rion** · 03-19-2009, 06:19 AM

I would start with fuel pressure. Probably wouldn't hurt to go ahead and swap that filter because you don't know the history of the car or when it was done last.

**Camaro98Z/28** · 03-19-2009, 08:08 AM

will do
what is the fuel pessure supposed to be (at key off and running at idle?)
thank you!

**0rion** · 03-19-2009, 08:18 AM

~58psi

**dklowrider** · 03-19-2009, 12:23 PM

its always good to have a clean fuel filter, but if there is a restriction in the fuel system it would get worse the harder you run it cuz the engine would be starving for fuel. he says it runs great when you run it hard. it seems we should be looking for sensors and stuff that deal with idle air mixture, etc. he says it started after pumping the pedal? theres no accelerator pump or anything so pumping it should just be opening the butterfly in the air intake? right?

**0rion** · 03-19-2009, 12:51 PM

that's why I recommended checking the fuel pressure. That will either confirm or rule out the pump pretty quickly and it's cheap to do. I agree and almost posted that if it were the pump it would get worse with load instead of getting better but the whirring he's describing sounds like the bearings in the pump to me so it's best to start with the fuel pressure and go from there.

**Camaro98Z/28** · 03-19-2009, 01:41 PM

replaced filter
problem still exists
still throwing p0300 at idle, and it is running like crap now even in the upper RPMS
fuel pressure is at 60 lbs

again does have new plugs and wires

any more ideas?

**0rion** · 03-19-2009, 02:02 PM

do you run an oil based filter and has your MAF sensor ever been cleaned? That's something I would look at next. You can get MAF cleaner at a parts store for just a couple bucks.

**Camaro98Z/28** · 03-19-2009, 02:12 PM

not throwing a maf code
yea i have a K&N filter however i have never oiled it, bought it new and have had it in for about 400 miles

**Camaro98Z/28** · 03-19-2009, 03:48 PM

neone?

**0rion** · 03-19-2009, 03:52 PM

just because you're not throwing a code doesn't mean it's not mis-reporting due to being dirty or having oil on it. If you're pump is good (which it sounds like it is) and you say you just changed plugs/wires not to long ago I would move to other areas. P0300 is a random mis-fire so it's not cylinder specific. To me that would almost rule out plugs, wires, or injectors. Not completely but I would look at the fueling system and spark system as whole units next. In other words it sounds like it would be something that would effect all the cylinders and not just 1. Maf, O2's, or possible vacuum leak come to mind.

**Camaro98Z/28** · 03-19-2009, 04:00 PM

def no vac leak
no hissing sounds at all
ill go clean the maf now

**0rion** · 03-19-2009, 04:06 PM

won't necessarily hear a hiss from it either. The back of the pcv hose has a tendency to crack where it bends to go into the intake. Might be something to check but usually if something like that happens you'll have a raised idle do to the extra air.

**Camaro98Z/28** · 03-19-2009, 04:18 PM

negatory
cleaned maf, was kinda dirty however
still rough as hell

its idling low, like i said as if it wants to stall out

**dklowrider** · 03-19-2009, 05:28 PM

Originally Posted by Camaro98Z/28

negatory
cleaned maf, was kinda dirty however
still rough as hell

its idling low, like i said as if it wants to stall out

fuel delivery seems to be ruled originally,and clogged cats would fall into the harder you run it the worse the problem category, but now its running bad idling and running hard. keep updates as you get to the problem if you would.

**edbird** · 03-20-2009, 03:26 AM

This site will help a great deal in diagnosing a PO300,check it out and let us know what you find:

http://www.aa1car.com/random-misfire/

**Camaro98Z/28** · 03-21-2009, 11:19 AM

well i gave up
i called my uncle whos the parts manager and it was towed to Century III Chevy

they are going to look at it and let me know what it is for free and let me decide from there what i want to do

i will update as soon as i know whats up!

**Cutlass** · 03-22-2009, 08:49 AM

Originally Posted by 0rion

P0300 is a random mis-fire so it's not cylinder specific. To me that would almost rule out plugs, wires, or injectors...

I'd like to correct a slight bit of misinfo here. P0300 on this vehicle means Engine Misfire Detected and not random misfire like on some newer vehicles. This vehicle doesn't report cylinder specific misfire info (i.e. P0301 cylinder #1 misfire). So it could be one cracked spark plug or a loose plug wire or a clogged injector causing a misfire on only one cylinder and throw a P0300.