CAR TALK

DEAR CAR TALK: I own a 2002 Chevy Suburban with 178,000 miles. I bought it from my brother-in-law for $3,000 for my son to drive while in college. It has died several times on the highway, causing him to pull over quickly to get out of the way of traffic. Before it dies, he feels a jerkiness or a rumbling. The car then loses acceleration, and pushing on the gas pedal gets no response. He can then coast to a stop or push the brake pedal to stop on the shoulder. It usually will restart in a minute or two, and runs normally thereafter. Occasionally, it has died several times within an hour while driving on the highway. Recently, the Suburban died on the highway on our way to visit family for a holiday. After restarting, it ran for over an hour, getting us to our destination without an issue. The dealership can't seem to find anything wrong with it. However, they say the fuel pump is on the low end, but they tell me it appears to be within the range required for the vehicle. What should I have the dealership replace or check?

-- Mike

DEAR MIKE: Have them replace the fuel pump. You know, those fuel pumps aren't what they used to be. Nowadays, a mere 175,000 miles, and poof, they're done.

You have the classic symptoms of a failing fuel pump. It usually dies intermittently, usually on the highway on long trips, after it's been working hard at high pressure and heating up.

It'll fail just as you described, by slowing down the flow of fuel, which makes the engine lose power, or chug or stutter, and finally conk out completely. After a short period of time, it'll cool off enough to allow you to restart the car and drive away. Until it fails again. Which is going to happen more and more often.

If you have a helpful mechanic, he might be willing to put a fuel-pressure gauge on the truck and drive the car home himself overnight. If he can get it to fail, he'll actually see the fuel pressure drop as the vehicle falters ... from 25 psi, to 15, to 10, to zero.

I suppose it could be a bad crank angle sensor instead, which could create the same symptoms. But the fact that your mechanic found the fuel pressure to be low (even if it was technically within specs at the time of testing) makes me think that the fuel pump is more likely at fault.

So unless you want to miss the next family gathering, or unless your son wants to miss his midterms, you should ask your mechanic to take another look at the fuel pump.

DEAR CAR TALK: I get a vibration noise behind the back seat area when the car is in drive, the lights are on and I stop at a light. If I turn off the lights and put the car in park, the vibration and sound go away. I am living and working in Japan, and my car is a 2010 Toyota Paseo. I've had it only two months. I removed items from the trunk to see if that is the problem, but I still get the vibration. Please give me some solutions. It's driving me nuts. If I can't get rid of the noise, I will have to get rid of the car.

-- Mike

DEAR MIKE: Well, now you know why the last guy sold it. You also know where to find him. So you can go visit him in the psych ward, and ask him what solutions he already tried.

Since it's coming from the back seat area (the car's, I assume, not yours), it's most likely to be something fairly benign, like the exhaust pipe vibrating against the underside of the car.

When you're stopped at a light in drive and your headlights are on, the engine speed is dragged down. It could be that when the engine is turning slowly and the geometry of the exhaust system is just so, the pipe between the catalytic converter and the muffler moves up just enough to touch the bottom of the car.

When you put the car into park and remove the power drain of the headlights, that results in an increase in idle speed and a slight change in the angle of the engine vis-a-vis the exhaust system. That could be enough to make the vibration go away. As an experiment, you might even be able to make the noise go away temporarily by holding your left foot on the brake and touching the gas pedal lightly.

But since the problem is pretty easy to reproduce, it should be a piece of cake to solve. Just take it to a mechanic, put your foot on the brake, put the car in drive, turn on the headlights and get the vibration going. Then the mechanic can grab the tailpipe, using a cloth or a pair of gloves, and see if he can stop or even just change the vibration.

If he can -- and I suspect he will be able to -- then it could be something simple, like an exhaust hanger that broke off. Or maybe you bent a section of the exhaust pipe when you drove over those sake barrels.

If he can't find anything wrong with the tailpipe, then you could have one or more worn-out or broken motor mounts. A broken motor mount also can cause the exhaust pipe to shift, because it allows the engine to move too much. He can test that, too, while you're in gear, by using a big pry bar against the engine and seeing if the engine moves more than it should or if shifting the engine changes the noise.

But go get it taken care of soon, Mike. We don't want to read that you went Japan Post-al on us.

Ray Magliozzi dispenses advice about cars in Car Talk every Saturday. Email him by visiting

cartalk.com

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