i have a 850 turbo volvo and i already replaced the wires and spark plugs and it still wasting me alot of gas. what else can be the problem?

 

What does "wasting me a lot of gas" mean? Is it leaking gas? Is it running rough? Getting 20 mpg?

 

fill it up to half a tank and gas last me only three days

 

You need to check the actual mileage. I had to FILL up 3 times the other day. I did drive 900 miles.

 

It's a little vague on what it is you have a problem/complaint with.

If you don't drive it for two weeks your gas will last a lot longer. If that sounds like I'm being an then you need to post some mileage numbers so we have an idea of what your car is doing. In three days you might drive 5 miles or you might drive a few hundred. The gas lasting three days is meaningless.

Replacing the distributor cap, rotor, ignition wires and spark plugs are part of normal maintenance and unless they have been ignored for too long it's just routine maintenance and not something that would improve mileage.
Did you replace the wires and plugs because it was running poorly or rough?
Does it have a MIL or check engine light on ??

 

My wife asked what your neighborhood is like? I did read about a guy that had one of his neighbors taking gas out of his car at night. Is your fuel filler door locked?

 

@RSPI that got me laughing. thats one bad neighborhood.lmao