Fuel System Problem!
 

My neighbors kid owns a 1991 firebird. I been helping him the last 2 days with his fuel system but I don't know much about cars and he doesn't have the money to take it to a mechanic so I been doing the best I can.

Anyway, his engine is ''starving'' for gas. We replaced the fuel filter thinking it was clogged and it worked for a day and then it started doing it again. It sputters and dies, it will run if you slam the gas in and floor it but as soon as you drop speed it doesn't get any gas and dies.'

I ran injector cleaner and fuel treatment as well....

Any IDeas, maybe he just got bad gas or gas with water iin it?

I would guess bad gas, empty the tank and put some good premium fuel in it (91 octane, 92 if you can get it). If that doesn't work I would start checking vaccum lines and carb.

ps: i'm no mechanic, just grew up with them..

same thing happened to me.. tried changing spark plugs, wires, ignition coils, and running some fuel injector cleaner through there.. didnt fix a thing.. took it to a mechanic and had to get all fuel injectors replaced - $800:(

What's the fuel pressure on the fuel line?
Could be the fuel pump.

this is where I would start, 91 firebird probably still uses a mechanical fuel pump bolted to the block driven off the camshaft. Should be around 6 or 7 psi, disconect the coilwire and pull the hose off in front of the filter turn the motor over and hold your finger over the hose and see if it has any pressure. You can also look at the pump and see if it's bad visually. There will be fuel leaking out of a pinhole on the pump on the backside of the diaphram.

If it's an electric pump you can take the hose off and do the same test as above, cant eally tell visually by looking at those though

Fuel pump... O2 censors.. Start at the pump you will figure it out.

Yeah another thing i forgot to mention, if I let it sit for a few hours it will run for awhile... then acts up again.

WHAT does that mean??

Thanks guys i love your responses btw just trying to help this kid out he has no ride to work.

it's a pontiac... throw away, buy any other car. problem solved.

If it's electrical :
It could be the computer chip brain box or whatever you want to call it. It heats up and it does not work. Run into this several times back in the day. If the box is external outside under the hood, for a test, start the car and let it run until it acts up, then run cool water over the box.

Or if it's fuel :
It could be a vapor lock, If the car has an electric fuel pump in the tank you can rule this out as they don't vapor lock.

Yeah Its a electronic pump!

So many things it could be.

Yep...fuel pump

Was the car running ok before?
Did the problem start after filling up with gas recently?
Has this car been sitting for an extended period of time (months) without being started?

Im assuming its a 305 with TBI with that said, my first stop would be the TPS( throttle position sensor) on the throttle body

Yeah if it was that it'd still idle so scrap that if it dies. Prolly injectors or pump, I had the same car back in 92. ;)

does it have an onboard computer? fuel injected? not sure about this year model but I had something similar happen to a truck I owned and it turned out to be the onboard computer.

fuel pump , if you put your ear by the fuel tank when you turn the key to the on position youll hear the pump then there you go , hit the tank with hammer . sound barbaric but it works

Could be faulty oxygen sensors, making the computer richen the air/fuel mixture so much it wont run, unless you hold the accelerator wide open which then lets in plenty of air, and then it runs.

I had a similar problem on a 96 corvette.

If this is what is happeneing, you'll notice a little black smoke coming out of the exhaust.

Yeah I sometimes hear a electronic squeel originatating from the gas tank or a low hum!

Yeah a little black smoke that comes out in puffs! but not very often