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#1202: Mud Chiggers in the Fuel Line


Mud Chigger in the Fuel Line!

Original Air Date: 01.14.2012

   Best Moment 1:27

Description: 
This week on Car Talk, life in the Big Easy is proving to be anything but that for Betsy and her truck. Since relocating to New Orleans, her Toyota has taken to spewing gas all over the place. Her mechanic's first guess? Mud chiggers in the fuel line! Entomology also comes into play later on, as Ray uses an ant colony to help explain why Nancy's Nissan won't start in cold weather unless she turns the heater on first. Also, Rob has to replace a Camry door that won't open; Susanne's DIY thermostat repair created a host of other problems, without fixing the one she was trying to address; and Daniel and his wife are struggling over the question, "Whose arm rest is this?" All this, plus the truth about wood-chip fired engines, and lots more, this week on Car Talk.

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Show Open Topic

Tom and Ray share a few handy metric conversions.

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As a zoologist I love it.

by Berkeleydoc

I liked your ant analogy for electrons. Some ants really do make ant bridges. But as someone from Harvard you should be familiar with the ant expert E. O. Wilson and know that worker ants are all sisters, not brothers. Keep up the good work

Favorite Moment: The mud chiggers

Mud Chigger Problem

by Mellowery

This depends a lot on if it is a pressure or vacuum on the tank. The exhaust heating the tank is feasible but if the same problem is happening after only a few seconds of running then that is likely not the problem. I think there is a vent problem for the tank. The tank should always be at the same pressure as the air around truck. If there is a vacuum it is because there is not enough venting to the tank. Most of the venting occurs through the charcoal canister. If the tank is not venting, as the engine runs it will draw a vacuum on the tank. If the vacuum is high enough it is probably pulling vacuum through the canister. The canister is connected to the tank and the fuel system to catch vapors from the system so they don't get released to the environment. Hence, if the canister is clogged, the vacuum will pull through the canister, through the fuel system, back to the fuel pick-up line from the tank, and dump it through the overflow. An easy check is disconnect all of the lines on the charcoal canister, put the cap back, and see if the problem persists. If it does not, replace the canister.

"Mud Chiggers!?"

by Nebraska Nucklehead

Knowing Cajun people and their flora/fauna...I'd say best guess would be crayfish, or "crawdads." My brother and I used to fish for them, with bacon and string. Good eating, but leave the heads alone!

Favorite Moment: The whole show. Look forward to it every week.

Great as usual... except

by whammy

One million microphones is just a phone, not a megaphone. Micro = .000001 (10^-6). Mega = 1000000 (10^6). So... 1000000*.000001 phone = 1 phone Keep up the good work, but check it first!

Metric Correction

by Photobug

Ammended for formatting: Greetings, wise ones. I would like to submit a correction to one of the arithmetic conversions from the metric system. The first conversion was “What is one million microphones in the metric system?” The answer was given as a megaphone, but that would incorrect from a metric standpoint. It is correct that a million in the metric system is represented by the prefix “mega”, but the prefix “micro” is also a metric prefix, for one millionth. Thus a “microphone” is one one-millionth of a phone. If we have a million of these one-millionth phones, we end up with a single phone. Another way to look at it is from a fraction standpoint: (1 phone / 1,000000) x (1,000,000/1) The 1,000,000’s will cancel and we’re left with 1 phone.

Metric Correction

by Photobug

Greetings, wise ones. I would like to submit a correction to one of the arithmetic conversions from the metric system. The first conversion was “What is one million microphones in the metric system?” The answer was given as a megaphone, but that would incorrect from a metric standpoint. It is correct that a million in the metric system is represented by the prefix “mega”, but the prefix “micro” is also a metric prefix, for one millionth. Thus a “microphone” is one one-millionth of a phone. If we have a million of these one-millionth phones, we end up with a single phone. Another way to look at it is from a fraction standpoint: 1 phone 1,000,000 ----------- X ----------- 1,000,000 1 The 1,000,000’s will cancel and we’re left with 1 phone.

Favorite Moment: The metric conversions

Mud chiggers

by Ednms

Searched forums on line. Seems number of people have problem. Seems heat related. Strong possibility that problem is caused by ethanol mix and gas is boiling to create pressure and spilling.

Favorite Moment: Puzzler

Change the gas cap!

by VT Girl

There may have been mud chiggers in the fuel line, but they probably made it to the gas cap too! It sounds like the vented cap is no longer vented. Buy a new cap and try that out before going to any other expense.

Favorite Moment: How can you pick just one?

Wood chip truck

by cap10david

I knew it was something like that, many thanks to your resident scientist for such a perfect explanation. You should find other slightly more challenging issues for him, for us who enjoy a little actual science mixed in.

Favorite Moment: Every time I find an NPR signal at the right time to catch the show!

Mud Chiggers

by cap10david

You guys really missed it and it could be extremely dangerous. I hope you can contact her and tell her to TOW it back to the shop. I had a similar issue years ago with a Ford ambulance conversion building up pressure in the fuel tank. They were nicknamed the Flaming Coffin. Cause is heat from the exhaust system raising the temp/pressure in the fuel tank. Heat = expansion = pressure. Whether the exhaust is leaking from her bad exhaust pipe, or a heat shield was left off by the boneheads who worked on it for her should be easy to discover.

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A Few Handy Metric Conversions

2 wharves = 1 paradox, and other handy metric conversions.

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