Expert: Sean Halliday - 12/26/2008

Question
QUESTION: Hi, I have an 87 Crown Vic-it was running great until my brother put some fuel injector cleaner in the tank. Now it runs rough, it stalls, sputters and backfires alot. It feels like it is not getting enough gas. It is also using more gas than it was before. The guy at the auto parts store reccomended that I try some c-foam, which I put in the tank. Please tell me what direction to go-I cannot afford a large repair bill as I am a single mom.

ANSWER: Change the fuel filter and see if it helps.

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QUESTION: Where is it,and how difficult is it to change? I have to do this myself. Should the tank be empty-does it make a difference?
Thanks!

ANSWER: It will be under the car near the passenger wheel at the rear.It is fairly difficult if you have never changed one as the fuel pressure must be released first.Best left to a shop or quick oil change garage such as jiffy lube or valvoline,or maybe your local gas staion.It is a hazardous job as fuel is highly inflammable.You will spill some so extreme care is needed.The tank doesnt need to be empty.I am wondering why your brother put the cleaner in the tank if the car was running ok?

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QUESTION: We changed the fuel filter-there was rust in it-but the problem is still the same-it will run sometimes a little sometimes alot-then it starts to backfire and bog down and it dies. Sometimes it will start right back up, sometimes it won't. It is burning very rich....almost seems as though it is telling another part of the car that it is getting too much gas. I don't know what to check next.....I would appreciate any advice

Answer
The thing that has happened is the injector cleaner your brother put in may have loosened any rust or dirt in the tank.It now seems to have gone through the fuel system.You will need to drain the tank and flush the fuel system,and fit another filter.Dump whatever fuel you have and renew that as well.My advice is to have the fuel system flushed by a shop.The additive he put in may not be compatible also.