I've got an 89 Firebird with a 305 AT. Once in a blue moon after I've say driven the car into town and parked. Then later get back in and start the car. Sometimes it will die right after it is started. Or sometimes it will die when I'm backing up, which I'm guessing cause the RPM's lower.

It doesn't do it too often. But it did it today, and I noticed there was a gurgling sound coming from the gas tank area. So, I figured that must of had something to do with the car dying after I restarted it. I can usually get it started fairly soon after this happens. Though, later on I noticed I didn't hear any gurgling anymore.

What is the cause of this?

 

Have you had a recent tune up done on your motor? I have that same problem with my gas tank sometimes except my makes a loud humming sound and if I release the pressure in my gas tank, it goes away. It comes back sometimes again as well. Haven't looked into the problem as of yet though.

 

What would be considered a tune up?

A year ago I replaced the wires, cap, rotor and fuel filter. Recently I replaced the plugs and EGR valve. The coil was replaced a few years ago. The air filter is good. PVC valve has been replaced.

Though, it doesn't sound like it would be the motor. It only does this once in a blue moon. But the last time it did it. I noticed a gurgling sound from the gas tank. So, that tells me it has something to do with the gas tank. Then a few minutes later, I'm able to start the engine like normal and no gurgling sound in the gas tank.

 

I don't know if your 305 is carbed or not but my 355 is. Whenever my car heats up to operating temp pressure builds up in my tank and pushes gas through the lines and into my carb, so if I get back in the car 10 minutes later its flooded out and I have to wait for it to clear, and even then my rpms are way lower and it doesn't really want to run.

 

It is stock TBI. I went ahead and replaced the gas cap. I had put one of those gas caps years ago that you don't have to remove when you fill up with gas. I didn't really like it. So, I put a Stant gas cap on, which I believe is the same thing as AC Delco.

Next time it does it, I'll pull the gas cap and see if that makes a difference with regards to the gurgling in the tank. It doesn't do it too often, so I may be a few months.

I wonder if the charcoal canister could have something to do with it?

 

I would say it might be do to excess pressure in tank. there is a vent valve in front on fuel tank on driver's side, it's white, might be clogged up or bad. Good idea to change it out on occasion anyways.
Also, I have had a starting problem and running problem after tank got warm from driving, was bad fuel pump which is common, and don't forget fuel filter.

 

Fuel filter has already been replaced. Is it hard to get to that vent valve? I'm guessing I could get to it from just crawling under there?

I don't have any running problems other than the engine likes to make "Doomphs" like someone choked it for a split second. And when it does that sometimes I see the RPM's dip very briefly. It guess it might look similar to a miss, but doesn't sound like a miss, more like a very brief choke. I never could figure that out, but its done that for at least 5 years, so I probably won't worry about it.

 

the vent valve is pretty easy if you can slide under the car. I think just a flat head screwdriver is all you need to change it out. it should be mounted to bottom of car and a rubber hose going to tank. it's up there pretty far but you should find it.
also, a lot of times the IAC will get dirty and make the hard have idle issues. maybe clean or replace that, it's easy to get to as well. 4 plug connector on bottom of throttle body, round piece that goes into it

 

IAC has already been cleaned twice. I've pretty much done all the typical cleaning and maintenance like plugs, wires, etc. I did start a thread on it a year ago, but didn't get much response. I did wonder if it could be the fuel pressure regulator? I did replace that 6 years ago when I took the throttle body apart and cleaned it up. I bought a throttle body gasket kit that included the FPR. I did remove all the smog stuff, but still have EGR valve. I had the smog tube holes in the exhaust plugged. Then I had the cat removed. I kinda wonder if that could be the problem.

I crawled under there yesterday but didn't see anything. You say its on the driver side? Is it on the side where you put the gas, or looking up from the rear bumper, or on the other side by the differential?

 

Bump.

I was in town today. Stopped by a store for 30 minutes or more. Then started the car and it died. Turn the key to "on", and I hear a gurgling sound coming from the rear. After a minute or so of waiting. I turn the key to "on", and NO gurgling sound. Car started right up.

What is the gurgling sound I'm hearing? I think knowing that would point me in the direction of what is wrong. From what I remember, it has only done this after I drove the car and parked it. I don't believe it has done this on a cold start.

 

Bump again. What causes gurgling in a gas tank?

 

Most likely the fuel is boiling in the lines at the engine & the TBI. This is from the hot soak after shut down.

The gurgling at key on is the vapors being returned to the fuel tank being pushed by the fuel pump. The return line is submerged in the tank.

Next time the car sits hot like this do a key-on, engine-off. After a couple of seconds key-off for about 10 seconds. Then do a key-on, engine-off again for a couple of seconds. Repeat this until the gurgling stops. At each key-on the pump will run for 2-seconds purging the line.

Then start the engine.

Many of the TBI trucks have a hot-restart module. This module runs the fuel pump for 20-seconds at key-on, engine-off. Just for this purpose.

The problem may go away once Summer hits. Right now the fuel composition being sold is bouncing back and forth between cold weather and warm weather blends. Get a cold weather blend on a hot day and you will have the issue of fuel boiling.

But get hot weather fuel on a cold day and the engine may not start. So it makes sense that the distribution of fuel will favor cold weather blends.

RBob.

 

So, is this a normal problem?

The interesting thing is it just does it every once in a while. Almost once in a blue moon. I just figured it would do it more often than that.

Is it possible there could be something wrong like a bad charcoal canister or something?

 

I wouldn't call this a "normal" problem but it is a fairly common problem. There are several other threads about this issue in the tech and tpi forums. Try searching: fuel boiling, fuel pump whine, and fuel tank pressure.

Even if your charcoal canister is bad it will still vent through the air port on top.

This seems to be a tricky problem to solve. The gurgling sound is your fuel boiling in the tank. It could be that the fuel is being heated too much which then causes the pressure issue. However, since increased pressure will lower the boiling point of the fuel, that could be the main issue too. Basically, all we have figured out for sure is that it is a fuel heating issue, a ventilation problem, or a combination of the two. Let us know if you find anything else out. Good luck!

By the way a vented gas cap seemed to help on my car.

 

Is the OEM gas cap a vented cap or sealed cap? I had just put on a new Stant gas cap from Advance. I believe it is the same as an AC Delco gas cap at the dealer.

I doubt I will get this figured out or try to figure it out. It only happens once in a blue moon, so obviously no shop would be able to figure it out. Unless I wanted to spend a ton of money on them checking everything thing out regarding the fuel system, which I don't plan to do.

So, I guess I won't worry about it then since it seems to be a complex problem.

I did read that fuel boiling could mess up the injectors?

Oh, and how exactly does the fuel boil when you shut the car off?

 

The OE cap is not vented.

I don't think the fuel boiling has anything to do with shutting off the engine other than you can actually hear it. I don't know about you but I can't hear much of anything near the exhaust with my engine running lol.

 

I'll probably keep searching around on Google about fuel boiling. Just strange it does it once in a blue moon vs. several times a week.

How is it this problem would go away when it gets summer? I think I remember it happening at the end of last summer when it was still pretty hot outside.

 

Mine only does it when it's really hot outside, like over 90* and I've been driving for a while.