Question about 1990 Cadillac Deville

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My 1990 cadillac seville is running rough changed spark plugs cap and rotor i changed the cat still run rough dont wanna spend more money if i step lightly on the gas its goes the more i step on it it gets slower and run really rough and loss of power i need to know what else to check unless the cat i put on is bad

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I have had this problem. if the spluttering start at a certain point on the fuel gauge. and when you fill it up it goes ok. then the fuel pump in the tank is breaking down. because when it gets to a level the pump has to work harder to pull up the fuel. however if it happens at any level of petrol that can be muck in the tank. or muck in the filler cap key hole. some cars breath through there. clean it in boiling water. now for muck in fuel try AMITECH products sludge remover. $8 or so. first . or you could try taking the pipe of the carbaretter and blowing air back into the tank. blasting away muck from pump it will not hurt it. might go for a while. failing that drain the tank and clean out with sludge remover. the other thing it could be is a slight hole in the tank. probably not. or a relay that gets hot.test relays do air thing try sludge remover and boil petrol cap before spending any money. use the air line that fills the tyres but take off pettrol cap first. just a little blast will do. few things to try there. hope it helps or you have to drop the tank clean it and change fuel pump. and thats expensive. liz

Posted on Mar 26, 2009

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