1991 mercury topaz
I try to start my car and she starts and runs good for twenty miles or so . Then it will try to start and want start .
you may have a fuel pump going bad or need to change your fuel filter.
Well, without seeing it, its really hard be certain, (obviously)... but as already mentioned, get the fuel filter changed just because its really cheap, ($5-10)... Then decide if you are going to be a Do It Yourselfer or if you're going to take it to a shop... Then regardless of your decision, buy a haynes/or chilton Tempo/Topaz manual and read the trouble shooting area, so you'll at least have an idea of what the shop is talking about so you don't get ripped off by them suggesting a bunch of unnecessary work... which leads to my next points... As mentioned get that fuel pump checked out...pressure test the lines,voltage,etc. Then if everything checks out, look into an ignition/or electrical problem... Get the distributor cap, rotor, spark plugs/wires/terminals checked if you don't know how to do that yourself... Have an amp/volt test done on your alternator or on the electrical system period... I had a similar problem and the alternator was bad, which in my case the car would run and then die, run and then die after a certain distance, then the following day crank, and just not start period...so I just replaced the alternator myself (not always easy if you're a beginner) and it fired up like a champ! BUT to make it clear, I also had a similar issue which was caused by a fuel pump going bad...so there are no guarantees that certain symptoms will not be the same or similar, but are caused by different things, so when in doubt, educate yourself, knowledge is power, contact a shop you trust, if you don't have one already, ask around with friends or family that have had good luck with someone! Good luck!