Fruit fly mystery confounding truck owner

I am at my wits’ end with this. I have fruit flies all over the cabin of my 2012 GMC Sierra 1500.

I never ever eat fruit to begin with, and I never allow anyone else to eat it in my truck. I have fogged the interior with enough Raid to cause genetic mutations in my grandchildren, to no avail. They eventually return within a week.

Could it be that, due to the fruit flies’ ability to mutate, they have developed into a strain of “super flies”?

Short of using a flame thrower, I can’t imagine what else to do here.

Upon further consideration, the flame thrower gambit is out. I don’t want to escalate the tensions. Any advice, no matter how bizarre or deviant, would help me. — David

Well, first of all, you should eat fruit, David. Fruits and vegetables are part of a healthy diet. And we’d like to see you outlive these fruit flies.

Fruit flies like rotting fruit — fruit that’s fermenting. And you’ve already tried the basic remedies.

You’ve eliminated any visible sources of food for them, and you’ve even resorted to the arena of chemical warfare. So what’s going on?

Honestly, I don’t know. I’m a mechanic, not an entomologist. But I’m guessing there’s a source of food for them somewhere in your truck.

While you don’t allow people to eat fruit in your truck, if you have kids, and they sit in the back where you can’t see them, all bets are off.

It’s possible someone dropped something onto the carpet and then mashed it in with a shoe to try to hide the evidence. So a thorough upholstery and carpet cleaning is a good place to start.

My other guess is that there’s some organic material that’s dropping onto the hood of your car, and entering the ventilation system through the cowl (the fresh air vents where your windshield meets the hood).

Let’s say something from a fruit tree dropped onto your car and some part of it fell through the cowl. It’s possible that it could rot and attract fruit flies there. And from there, the flies made their way through your ventilation system.

Maybe it doesn’t take actual fruit to satisfy them? Maybe tree sap is good enough if they can’t find a local watermelon stand that’s open?

That could explain why they keep coming back, even after you napalm the inside of the truck.

So I’d start by looking at what trees you’re parking under. And once you’re sure you’re not continually replenishing their food supply from above, then the solution may involve nuking the cowl area with the fan on full blast.

If that doesn’t work, you may need to get into the HVAC system itself to clean it out. That stuff is all tucked up under the dashboard and not easy to get to.

So we’ll hope that a thorough cleaning, more judicious parking and maybe some highly targeted chemical application ends your infestation.

If not, you’ll have to move to Fairbanks and sell the truck there next winter during dormant season. Good luck.

Hi. I have a 1989 Lincoln Town Car that sometimes cuts out when I give it very little gas — like when I’m inching my way along a drive-thru line.

Any idea what could cause this problem? I’ve replaced the spark plugs, wires, cap, fuel filters and fuel pump. Thanks. — Joshua

Wow, Joshua. An ’89 Town Car is a beast from another era. That car probably dropped a lot of people off at the Pan American Airlines terminal.

This thing is so old that’s it’s carbureted. And I think that’s where the problem lies.

A carburetor has a little pump built into it called the accelerator pump. And the accelerator pump’s job is to squirt in a little extra gasoline when you first step on the gas pedal.

Once the gasoline is flowing, the suction created by the pistons does its job, and the carburetor has all the fuel it needs to respond to your acceleration requests. But in that first second or so, right when you go from idle to accelerating, if the engine doesn’t get that extra shot of gas, it’ll stall.

So I think you have a bad accelerator pump.

The bad news is that you probably didn’t need any of that other stuff you bought and installed — the wires, plugs, fuel pump, etc.

But the good news is accelerator pumps are cheap! You can probably find one online for about $10.

And if I remember correctly, on this car, the accelerator pump sits right on the front of the carburetor and attaches with four simple screws. One of which you’ll certainly lose if you try to do this yourself. But it’s a job a DIYer can tackle. However, you could also look for a mechanic who remembers how a carburetor works. If you pay him for an hour’s labor, he might not only swap out the accelerator pump for you but also blow out the accelerator pump’s fuel passage with some brain-cell killing carburetor cleaner. And that’s not a bad idea, too, at this point.