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Last week I had a 50 percent drop in fuel mileage in my '86 Turbo Z. Anyone have an idea what could cause this or what/how to check for a problem? Fuel injectors? I think I smell fuel, but can not find any indications when I stop. Do have a stronger exhaust odor though?
 

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1966 Crown Coupe, 2016 200 S AWD, 1962 Lark Daytona V8.
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Welcome to Allpar. Pay attention to the odors. Raw fuel leaks may dry and leave behind a stain. If you smell it while driving, it may be coming from up front and entering the passenger compartment through the cowl fresh air intake.
If you smell it when walking next to the car, check for tank or fuel line supply/return leaks. The evaporative (fuel vapor) emissions system can also cause raw fuel odors, but won't really affect fuel economy.
A stronger exhaust odor may indicate a 'rich' fuel mixture that may be from the EFI sensors or system. Any active or pending fault codes?
Colder weather will bring lower fuel economy.
 

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Pay attention to the gas tank weld seams (I had a leak there once) and to the fuel lines, especially where they follow the RR frame rail to the tank. I had a very faint odor of gas there. I reached up and crushed the lines, they crumbled with a gentle squeeze, and had pinholes all over them. But not a drop on the ground, nothing even visible on the lines.
 

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Could someone have siphoned the gas out?
 

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If you say a drop in the fuel level there is most definitely a leak. Check the rubber from the hard lines to the engine. Since it's an '86 Turbo Z it has the log intake with injectors fed by the fuel rail and a return line. Check the feed to the fuel pressure regulator at the fuel rail to insure no leak there as well as the return line. Then on the passenger side in front of the rear tire there is a filter with an in and out line. Check these and then finally at the tank. All in all there could be six places where the rubber could be broken and leaking. Also, if you find no leak in the rubber or at the clamps check the hard lines.

CAUTION!!! this is gas... I know you know this but... many a Daytona has been lost due to fire related to leaking fuel lines/hoses/clamps etc. Have someone at the ignition to turn the car off as soon as the leak is discovered.
 

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CAUTION!!! this is gas... I know you know this but... many a Daytona has been lost due to fire related to leaking fuel lines/hoses/clamps etc. Have someone at the ignition to turn the car off as soon as the leak is discovered.
Maybe hot wire the fuel pump to look for leaks so the engine and esp the turbo charger right below those fuel lines stay nice and cold. Yea - I carry a fire extinguisher with my '85 cause I used the recall parts to install the intercooler :).
 
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