Question to the STIG - Ford Mustang Forum
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post #1 of 5 (permalink) Old 1 Week Ago Thread Starter
Blacksunshinee's Avatar
Joined: Aug 2015
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Question to the STIG

I found in one of these pages something you were suggesting to another member. Can you explain what are the consequences of a clogged cast tank? see attached


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post #2 of 5 (permalink) Old 1 Week Ago
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He explained it in that post. When fuel is being sucked from the tank, it created vacuum and eventually it will stop being able to pull fuel and it’ll starve the engine.

Think about pouring gas from a gas can that doesn’t have a vent at the back of the can, what happens? It sucks in and collapses.

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post #3 of 5 (permalink) Old 1 Week Ago Thread Starter
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I see. The reason why I am asking it's because every time my tank is low in fuel (less than a quarter) experiences less power and when it's filled the car has more power but also when is hot is when the car runs sluggish and when the temperature is below 40's the car has lots of power. Day and night!

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post #4 of 5 (permalink) Old 1 Week Ago
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For the 1999-2004 model year the gas tank is vented through the charcoal canister. The default position of the CV vent solenoid is open(venting). So if:
  • The CV vent solenoid is clogged/closed or
  • The charcoal canister is clogged.

It will create venting problems inside the gas tank.

However if this problem only happens when low on gas, I would also rule out:
  • water in the gas tank
  • Trash in the gas tank.
  • a pin hole leak in the flexible ling between the pump basket and the gas tank hat.

But why guess? Test! What is the fuel pressure when the tank is full vs almost empty? What do the long term and short term fuel trims do?
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post #5 of 5 (permalink) Old 1 Week Ago
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Could be a failing fuel pump. They are cooled by submersion in fuel and when the fuel is low it could be getting sensitive to running hotter. This is a pretty common failure mode for all types of in-tank fuel pumps.
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