2001 Starting Problems, etc.

Hey folks.

My wife has a 2001 SE. 3.4 V6. About 9 months ago, we replaced a bad battery and had various instances of the security lock engaging. Talked to the local dealerships and the service tech said that we need to clear the codes out of there. We knew how to do the "10 minutes and wait" reset, and although it was an inconvienence, it wasn't a huge crisis.

Mysteriously, the problem went away a while back and we just brushed it off.

Yesterday, she was driving home from work and the car just shut off and she had to coast to the side of the road. Calls me frantic, and says that the car isn't out of gas, since the amber light didn't come on and it had 1/8th of a tank. State Police show up and demand it gets towed, and $134 later it's sitting in my driveway, but she is safe and sound. ( I was on the road, drive truck and was still in Hartford, CT)

This morning, I went out and dumped a couple of gallons of gas in it, turn the key and it fires right up. Ugh. So I figure the gauge is off, and I drive it to the gas station, fill it up, and once again, it won't start. ( BTW, I notice the cruise light blinking on and off on the way there ). So now I push the car out of the way, and try to start it, and backtrack and take the cap off the tank as it was off when I started it in my driveway and it fires up again. So, in essence if I relieve the pressure off the tank, it runs. Weird. Cruise light is now off. No check engine or any other lights as well.

I did some trolling on the net trying to find any answers before I just start throwing parts at the problem, and it seems like a common issue with these cars, and a lot of folks buy an expensive fuel pump when it really isn't needed. Also looks like a lot of folks spend a lot of cash at repair shops and dealerships, and they're basically taking crack shots at it while the register rings up.

I'll try the basics over the weekend - the car is well maintained - regular oil changes, filter changes ( fuel filter is less than 9 mos. old). It is due for a major tune-up and I had it scheduled next week while my wife is away on a trip. I was also planning on getting the ECM codes anaylized and cleared.

Any ideas? I appreciate your help.

Thanks.

Steve

welcome to AF Steve. Ya the damn security system sucks on 01's. I would suggest getting it disabled asap. Hundreds of GMs I've workked on in the past couple years, with the security feature on, has had troubles too. the 10 min thing is only a temp fix. I dont know right off hand exactly how to shut it off but there are many in here that will know, so hang loose and we'll get it straight.

I hav heard others leaving the gas cap off and thier cars wont start or run right, i find that bs too, I've left mine at the station more than once and had no problems with 'air in the line' or anything else unusual. Some gas gauges on GAs dont work proper, giving you more or less than it accually have. My 99s that way, I'm just waiting till the fuel pump goes before I pull the tank. I keep track with the mile trip count, I hav a 12gal tank and I get around 220-250 miles then start looking for a station. On the highway I can get 350miles on 10gals, 10mpg differance, thats strange.

The dealershits will throw parts all day rather than say 'we dont know whats wrong'. I do suggest trying to pull the codes, this will help eminsly.

I hav heard others leaving the gas cap off and thier cars wont start or run right, i find that bs too

Thanks for the reply. Was kind of leaning towards whether or not the fuel pump was slowly failing since it seems to work fine with the cap off.

When I put the cap on the tank, the car won't run.

I don't know the mechanics of a vapor recovery system, and I was wondering if something goes defective in it, will the tank not properly vent and create some kind of vacuum and starve the pump for fuel?

Regardless, I'll have the codes pulled and get the thing into the shop. It just didn't want them throwing a $500 fuel pump at the problem, if it really doesn't need one.

While I also don't know the exact mechanincs of the fuel system, there is one basic thing I do know, either the fuel pump has a vent line to let air into the tank, or the cap lets the air into the tank. Maybe someone on here knows for sure which way it works, i'd guess you either have a vent line plugged or a bad fuel cap. Maybe a dealership will know if there is a vent line, or even if the vent line has some sort of a valve to keep fuel from running out if the vehicle rolls over, maybe thats built into the fuel pump, since I have never seen such a thing. I have heard a rumor that the fuel pump works by pressurizing the fuel tank with air, but im not sure I believe that since it will run with the cap off. I do know starting in the 90's GM started having the computer monitor if the fuel tank held pressure, i've seen a million cases of the check engine light coming on because the fuel cap wasn't tight. Sorry I can't tell you exactly where to get the answers, or the exact problem, maybe someone has more info for you, if not a new fuel cap is a cheap try.

SteveLF hav you tried getting the fuel pressure checked at the valve on the fuel rail? This being a 2001 I wouldnt think the fuel pump would be out already but none the less it is possible. i still say its the security system fauling things up.

If you take it to a shop, tell them not to fix anything till they know for sure and call you to check if you want them to do the work or not. At least this way if its something you feel comforable doing you'll save your self some crazy labor fees.

While I also don't know the exact mechanincs of the fuel system, there is one basic thing I do know, either the fuel pump has a vent line to let air into the tank, or the cap lets the air into the tank. Maybe someone on here knows for sure which way it works, i'd guess you either have a vent line plugged or a bad fuel cap.

Upon reading the manual and checking the car over ( runs fine with the cap on now - go figure ) it looks like the cap has some sort of vent/valve built into it to let air in the tank. Could have just been a fluke where it stuck shut.

There is also a vent valve near the tank on the underbelly of the car, and I will probably investigate that as well. Seems that the vapor recovery system works by capturing the vapors off the tank, storing them in the charcoal canister and then holding them until engine temp and conditions are ideal for purging the canister, burning the vapors and repeating the cycle. Regardless, as you burn off gas, air has to replace it, so I'm leaning towards a stuck vent. The vapor recovery system doesn't seem to replenish the air, to me it seems like it would only contribute to the problem.

Since it generated no faults through the ECM, I know I won't get anywhere by putting it in the dealership. I'll just pour over the fuel system and probably clean the rest of the valves and idle switches as well.

I'll let you know what I find - thanks for the help so far.