gas mileage
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Joined: Nov 2003
Posts: 1,006
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From: Sussex County, DE
As previously suggested, check for codes. Also check for vaccum leaks. Especially check to see that the vaccum line to the fuel pressure regulator is attached. If not hooked up, it can cause an increase in fuel consumption and NOT set a trouble code. Places to check for vaccum leaks would be around the runners, all vaccum hoses, and at the injectors. Lastly, if your engine had a manifold replacement due to coolant consumption, replace the O2 sensors, even if no code is set for them. The silicates in conventional coolants will contaminate an O2 sensor and make it's readings ineffective, usually resulting in a false lean signal to the computer, causing the computer to increase the injector duty cycle to add additional fuel to balance out the percieved lean condition.
Dave
Dave
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New User
Joined: Apr 2003
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From: amherst
i have a 4.9l 300 standard 5 speed.was getting around 20 mpg,but since i had the intake manifold gasket replaced it dropped to around 15 mpg
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Joined: Apr 2002
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Good way to check for vac leaks, if you need to know, is to take a can of carb cleaner that is safe for oxygen sensors and spray it around likely spots that are leaking while truck is idling. If you hear a change that's where the leak is.
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