2000 mazada 626 on sometimes will not start. starter engages, spark to plugs, and I can hear the fuel pump running. after it sits for a while it will start and run for a week before it happens again. I have replace the gas filter.

Turn your ignition to on BUT do Not engage the starter.You should hear the fuel pump running to put fuel to the carb,when the noise stops that means fuel is at he carb, then engage starter and see if starts easily.Do NOT touch the gas pedal.If it starts easily the only problem is that the fuel line is draining back down to the tank after it sits for a while.Not a big deal.

Check your fuel filter. If it has not been changed for awhile, it may be plugged. The car would then be starved for fuel and quit. After sitting for awhile, enough fuel may get through, but after running a short time it will die again for lack of fuel.
Another thing to check is your ability to get spark to the spark plugs. You coil(s) may have died and need to be replaced.
You could also have a crack in your distributor cap if you have one and the spark is shorting to ground. You may also have faulty spark plug wires that need to be replaced. You could also have a blown fuse to feeds battery power to the spark coil. You could also have an open ballast resistor in line with your spark coil and it needs to be replaced. Gas or Spark, but how the spark is generated really depends a lot on the car. Here's a test you can run to check for whether your car is starved for gas: Get a can of starter fuel and spray a couple of puffs (small amount) into your air cleaner. Once the battery is charged, try starting it. If it starts running and then dies, you can be pretty sure you have a gas problem.
One last possibility is that your exhaust is totally plugged. Do you feel or can an assistant feel any puffs or unburned exhaust coming out of the tail pipe? If no vapors come out, it could be plugged.
Oh, one other thing it could be. Your plugs may be flooded, especially if you pumped the gas pedal and it is a new model car. If it smells strongly of gas, your spark plugs may be wet (flooded) with gas. In that case, remove all spark plugs, disconnect your spark system, turn the engine over to blow out excess fuel, dry your spark plugs and reinstall them.

IF IT WILL RUN WITH STATER FLUID YOU HAVE A FUEL ISSUE. SINCE PUMP SOUNDS DIFFERENT I WOULD START THERE. CHECK FOR VOLUME & PRESSURE ON FUEL RAIL IF IT NOES NOT THEN THE PROBLEM IS IGNITON, CHECK FOR SPARK

You can hear the started going but engine want crank ???????
The starter is spinning the engine over , but won't start an run ! The starter is cranking the engine ,but the engine doesn't start an run . OK ,enough of that > When it won't start (run ) what's missing ? Ignition spark or no fuel pressure ? Video's on youtube showing how to test for these . Has to be one or the other .

Are the plugs wet with fuel?
Check for spark. No spark? it may be the ignition module.

Plugs dry and spark present? No fuel?Spray a little starting fluid and see if it will run on that.
Then check pump fuses and for fuel pump noise.

It could be the fuel pump. Sometimes you can hear them engage, but they are not pushing enough fuel pressure to run the car. This can be checked.

Hi, if the car turn over, and it don't start. Then it is like the engine don't get fuel. Or bad a spark plugs. Most common problem is the fuel pump going bad.

It could also be a bad fuse, but a easy way to check if the fuel pump is ok is to have someone stand at the back of the car when you turn the ignition. The fuel pump should make a buzzing sound for a few seconds. And if you don't start the car right away the fuel pump will stop.

If you don't hear any buzzing from the fuel pump/fuel tank then you have a bad fuel pump............

sounds like either the teeth on the flywheel or on the starter itself are missing a few gears or the sylinoid is not ingaging the starter enough

Doesn't sound like starter is engaging fully with flywheel, is that correct? You may have to shim it a little one way or another to get it properly aligned. When starter off, did you take a look at teeth on flywheel to see if worn off perhaps? With key off, try turning engine over by hand slightly to allow for different position on flywheel and see of that works.

hello,maybe fuel pump,, or your k-40 relay module(fuel pump relay)better to install a fuel gauge to determine, fuel pump or your fuel pump relay,ty