Pump Down the Mileage

Feb 14, 1998

RAY: Ha! We're back. You're listening to Car Talk with us, Click and Clack, the Tappet Brothers, and we're here to discuss cars, car repairs, and-a.

TOM: And-a.

RAY: The new puzzler.

TOM: Yeah, OK. You said by your own admission was not interesting, not folkloric, not challenging, but it was automotive.

RAY: It was automotive.

TOM: Like John Wayne when he was in his first movie, and they asked his father well, how do you like it? He said he was tall. OK, automotive is fine.

RAY: Here it is. A fellow comes into the shop recently, the other day, a few weeks, last year. I don't know -- maybe about nine or ten years ago, and he complains that his Volvo, an older Volvo, is misbehaving. It seems to lose power. It sputters. It has difficulty climbing hills. It's especially bad if the tank is less than half full. We say, huh, piece of cake. It's a classic problems of the intake fuel pump being kaput. Many Volvos for years and years, Volvos have had a pump in the tank, which is a feeder pump, which pushes the fuel to the main fuel pump, which is located outside the tank underneath the car. Got it?

TOM: Got it.

RAY: So when the intake pump feels, the car will still continue to run because the main pump will actually pull...

TOM: Suck it out.

RAY: ...fuel out of the tank rather than have it pushed and assisted by this feeder pump or intake pump. But...

TOM: It won't work great.

RAY: It won't work great, and the car will suffer from poor performance because of the fact that it hasn't got sufficient fuel pressure.

TOM: Classic symptoms that he had.

RAY: Classic symptoms. So he says go ahead and replace the pump for $900. See if I care.

TOM: You guys are so sure of this diagnosis, go ahead.

RAY: So we do it. Off he goes. A week or two later he returns and says geez, the car runs great, but my mileage is down. You must have done something, and we say of course not. This is the first line of defense. We did nothing; we're innocent. How can we have done anything to affect your mileage? He says it's off at least ten percent. We say well...geez.

TOM: Ten percent is hard to measure.

RAY: It is hard to measure.

TOM: So you say fine.

RAY: We throw him out on his butt.

TOM: Of course.

RAY: He comes back persistently a few weeks later and says it's down even more, maybe 15 percent and getting worse. You did something wrong. Again we reassure him that we did nothing wrong. He says I know it has something to do with that pump you put in the tank.

TOM: Because it was coincidental. Coincidental with your putting in the pump, but he doesn't think it was coincidental.

RAY: No, so we go ahead and as a courtesy, we check his emissions, which are perfect -- the timing and all that stuff.

TOM: It's called placate him.

RAY: Placating. There you go!

TOM: Before you throw him out on his butt again.

RAY: And we throw him right out. And we come to realize when he returns for the third time with his lawyer.

TOM: That he's right.

RAY: That he's right and even though we did nothing wrong, putting in the new pump made his mileage drop.

TOM: Whoa!

RAY: And he was absolutely right. It was because we put the new pump in that his mileage dropped precipitously. The repair was done correctly. The pump was installed perfectly correctly. And yet he was correct that by putting in the pump, we reduced his gas mileage. How could this be? How could this be? How could this be!

TOM: Yeah, it's good.

RAY: Now if you think you know the answer -- and the question is obviously, what? What's going on here? What's shakin.' Now if you think you know the answer...

TOM: Does it have anything to do with the dead bodies in the trunk that they discovered later?


RAY: We did, by putting in the new pump, make his mileage drop. We missed something. We missed something. What we missed is that there is a piece of tubing that goes between the tank pump and the main pump, and it had a little pinhole in it.

TOM: So the little pump inside the gas tank pumps fuel along this tube into the main pump. The main pump then pushes it the rest of the way to the engine.

RAY: Now with the intake pump broken, this little pinhole did not cause gasoline to leak out because there was suction created in that tube. When we replaced the feeder pump, we created positive pressure in that line between the two pumps. Even though most of it was being sent to the injectors, just enough was leaking out through this little pinhole to cause this 12-point-7-5 percent drop in mileage. So he was right, even though we didn't do anything wrong.

TOM: I mean that's an interesting...what if that were a -- this brings up an issue, a legal issue. What if this were a life threatening thing.

RAY: What if his car had burst...

TOM: What if it burst into flames and he died? Then he wouldn't be able to see. Well, what if he didn't quite die, unfortunately.

RAY: Burned beyond recognition?

TOM: Burned beyond recognition.

RAY: But his memory was intact, and he could call his lawyer.

TOM: He still had enough energy left to call his lawyer, right. The thing is are you required then to look to see that there are no little pinholes, which could never, ever happen except once in a while because you would install the pump, you get in the car, you turn the car, the thing would run like a dream, and you'd say it's running like a dream, everything is fine.

RAY: Yeah, we never saw the pinhole because it was pointing up and spraying gasoline on the under side of his car.

TOM: Sure, and you wouldn't even see it.

RAY: Right near that hot exhaust system.

TOM: You wouldn't see it. Interesting.

RAY: Interesting.

TOM: Yeah.

RAY: Yeah, whose responsibility is it? Ours.

TOM: It is.

RAY: It is, unfortunately.

TOM: I don't think so.

RAY: Well, the judge thought so. Anyway, who's our winner?

TOM: The winner is James Nofi, N-o-f-i, from Flushing, New York.

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