High pitched sound from rear wheels....

[jacklift]

Hello again. I have a problem on my 1992 Lumina (with the dreaded Methanol conversion/variable fuel option). 3.1 engine.

For about the past three weeks, when I have driven for just a few miles, and I get out of the car, I hear a high pitched sound emanating from approximately between my rear wheels (I want to say it is coming from my fuel tank or gas filter, but can't really say). This happens about 70% of the time. Then it just stops on its own. Mind you, I have exited the car and the key if OFF, and it is still making that sound. It goes away in about 30-45 seconds. There are no visible leaks under the car.

I would say that it sounds somewhat like that annoying sound that tells you your lights are still on, or your keys are still in the ignition, or your seat belt isn't fastened, but only higher pitched. Could this be the pressure in the gas line somehow leaking through the fuel filter (which is about in the middle of the car, underneath) causing a "whistling" effect? Has anybody experienced anything like this?

I do have a second question, while I am thinking about it. What do I have to do to convert this car back to a non-methanol car. My thinking would be to replace;

fuel pump (had to be replaced once ---$500!!! for the dreaded methanol fuel pump)

ECM

Is my thinking correct?

Thanks again for all of your invaluable help in solving these annoyances.

Jack.

[cadgear]

It does sound like a pressure deal. Check the evap system as well as all fuel fittings. I think the charcoal canister is somewhere back there. I'm not sure what would be needed to convert, I've never even heard of the variable fuel option. Sounds interesting.

[jeffcoslacker]

I'm thinking you are hearing some kind of vent or pressure release valve in the tank that is not working quietly. Ball check type valves can make buzzing, whistling, wheezing and a variety of other sounds, depending on the design.

About your change over, you'd have to do some research with the conversion supplier to find out how involved the conversion to flex fuel is, and reverse engineer it from there. But the problem is, you may run into emissions non-compliance problems, like all those who converted their diesel Buicks and such to run gas. The Fed says it's gotta have the emissions controls it came with from the manufacturer. If the flex conversion includes any "unique" sensors or controls, it may not pass a legit visual inspection. Suck to go to all the trouble and not be able to license it. I'd find out first.

[cadgear]

Dang, Jeff. You must be tied into my computer. The last few posts I've made you've jumped in front or right behind me. I think you're STALKING me.....

or maybe you're just gosh darn good.

[jeffcoslacker]

Originally Posted by cadgear

Dang, Jeff. You must be tied into my computer. The last few posts I've made you've jumped in front or right behind me. I think you're STALKING me.....

or maybe you're just gosh darn good.

I was thinking the same thing about you

[richtazz]

try something simple, and replace your gas cap. Make sure you tighten it to a minimum three clicks and see if your squeal goes away. As far as I know, the biggest difference in the methanol conversion is they use a different type of rubber for all the flex lines and injector o-rings that is resistant to methanol, as well as in the pump/strainer assembly.

[jeffcoslacker]

Originally Posted by richtazz

try something simple, and replace your gas cap. Make sure you tighten it to a minimum three clicks and see if your squeal goes away. As far as I know, the biggest difference in the methanol conversion is they use a different type of rubber for all the flex lines and injector o-rings that is resistant to methanol, as well as in the pump/strainer assembly.

He has some kind of ratio meter in it also, which I assume the ECM uses to modify some variables.

[richtazz]

You're right, I forgot about that Jeff.