One of those mysteries

[TruthWalleyes]

This one puzzles me, and i'm not too concerned about it, but maybe there's a reasonable explanation and possible the situation is foreshadowing another event...Anyway, see if you can explain this one.

Friday night I drove my bravada 100 miles, hitting no pot holes etc. with about 800# of cargo on board (Some pavers for mom). I get to my parents house, unload the vehicle, pressure wash the vehicle including tires and park it for the night.

Saturday morning a tire is completely flat.

No history of prior tire problems. No leaks, nadda.

I filled the tire. Removed it. Rinsed with soap and water 3 times and found no leak. I was puzzled, so i checked the pressure again, and installed the tire back onto the vehicle.

Well its been since saturday, and the tire has not changed pressure.

What caused this flat?

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2nd question: This same bravada (4.3L, 1998, AWD) can be pretty noisy. Kind of a whine. I think it is a fuel pump. The reason i think it is a fuel pump is because when i turn the key over (not starting) the fuel pump primes and it is the same whine that i hear when the vehicle runs...So should this pump be replaced? Is it a sign of a pump going bad, or just a typical noisy fuel pump.

[Macgyver55]

A prankster?

[Scott K]

A prankster?

This was my thought as well

[Jeremy airjer W]

Aluminum wheels?

Usually bead leaks will drop tire pressure to around 20 psi and then stop leaking. I have run into completely flat tires that have no puncture leaks and when filled with air have no signs of bead leaks as well. When the tire is removed from the wheel it is usually apparent that a corroded bead is the issue. I think the fact that the tire has deflated completely has something to do with it resealing once air is added. The other possibility is that the bead leak is so slow that it would take a much longer period of time to show up.

Here's another interesting tire repair fact. Most tire punctures are found within 90 degrees of the valve stem. I noticed this about 15 years ago.

[Macgyver55]

I'd bet the house that ALL punctures are within 180 degrees of the stem!

[PiedmontAngler]

I had that happen to my truck this winter. Aluminum wheels. My best guess was bead leak. No other holes or issues. Cleaned it and filled it up and it hasn't changed since. Hope your problems are gone too.

[TruthWalleyes]

My first thought was prankster...but not likely considering where my vehicle was parked.

Aluminum Wheels. I've never not been able to find the leak so this was a first for me.

Anybody have a response to my second question about the fuel pump?

[Macgyver55]

I've heard some pretty noisy pumps that went a long time and some quiet ones that didn't last long. How many miles on it, has it always been noisy, and how big of an inconvenience are you willing to put up with if it goes?

[Eric Wettschreck]

Andy, Justine used (key word is used) to have a Bravada similar to yours. I replaced the fuel pump in it. It's do-able but wasn't a fun job.

I hated that Bravada. I'm glad it's gone.

[TruthWalleyes]

LOL, Buying the bravada was a terrible decision!

Sounds like the fuel pump could go at any time then and i should have it replaced. I think i'll have a shop do that one, i do most of my maintenance on my vehicles but i've never messed around with a gas tank.

Thanks for the input gents.

[Jeremy airjer W]

There's a second question?

The noise may not get any better with a new pump. If the pump has some miles on it and the filter is still original than it would not be a wasted investment to replace the pump. Just be prepaired to hear the same noise. Don't get a cheap pump either. A/c delco or Delphi would be good options. AIRTEX/ carter would be undesirable options.

[Eric Wettschreck]

If I remember correctly, the pump cartridge and filter was right around 400 bucks for parts alone.

[TruthWalleyes]

So then the noise is not an indication of pump failure if a new pump will make the same noise. What is causing the noise, and when do you decide to replace a fuel pump - When it dies, or is there any testing to see if pump is still in good working condition?

I just figured since it was so noisy that it was going bad, am i understanding this correctly?

[Jeremy airjer W]

When it stops making noise is when you will have the biggest problem!

Replacing it because it is noisy may not resolve the noise issue. Older GM vehicles have always has noisy pumps. Some more than others. If it makes you feel better to replace it that go ahead and do it, just be prepared to hear roughly the same noise when your done.

[Walleyehooker]

Making noise can be a sign that they are about to go out but still can last another 6 months to a year+. You just never know when it will give up. Not to bad of a job if your tank is low on fuel. Should be a video on U tube on how to do it.

Corrosion on aluminum rims is a common problem and causes leaks

[TruthWalleyes]

Replacing the fuel pump doesn't look to be too big of a job. Something i could easily do. So how does one drain the fuel tank? Is there a drain plug on the tank, or do you just run it very low on fuel and then drop the tank?

[Scott K]

Run it low is the best way. No drain on the tank.

[Walleyehooker]

Running it down is the easiest and makes it a lot easier to handle when you pull it out especially if the vehicle isnt on a lift and you have the proper jack. Always a danger when gas is involved. I know a guy that pulled one of these out with a trouble light near by and the light bulb broke and started a fire. Burnt him up pretty good and also burnt his shop down. Stuff happens!!!!!!!!!!

[Eric Wettschreck]

There's a vacuum line on the top front of the tank that's real difficult to see if you don't know it's there. Make sure you take it off before you try to drop the tank.

Lots of the job is accessable if you remove the drivers side rear tire and go in from there.

It was a while ago, but if I remember correctly you should replace the wiring harness also. There may be some splicing of wires involved. Not that big of a deal with the pump cartridge in your hand.

[Walleyehooker]

You may also need a special tool to disconect the gas lines from the fuel pump. I got one at Sears for about $10. Auto parts stores will have them to.

[TruthWalleyes]

Thanks for the help everyone.