We channged the starter cause we thought it.

Check for a spark

In order to check for a spark at one of the spark plug wires, remove the spark plug wire from the spark plug. Connect it to a spark tester and connect the other end of the spark tester to a good engine ground (a bolt will do fine). Have an assistant to crank the engine and you should see a spark jump the gap in the spark tester. If so, the ignition system is doing its’ job. If not more testing of the ignition system is required.
If a spark tester is not available, remove the spark plug wire from the spark plug, put a screwdriver into the end of the spark plug wire and lay it (horizontally) on a metal part of the engine (make sure you have about a  inch gap between the metal part of the screwdriver and the metal part of the engine). Have an assistant to crank the engine and you should see a spark jump from the end of the spark plug wire to the metal engine surface. If so, the ignition system is working.

Also

Check for fuel
If you suspect that it's not getting fuel, move the snorkel away from the throttle body enough to spray some carburetor cleaner into the intake manifold, replace the snorkel and then try to start the engine. If it starts (or tries to start) and then dies, the problem is that it isn't getting gas for some reason. The fuel system will have to be diagnosed.
If the result of the above fuel check shows that the engine isn't getting fuel this is the next step:

Checking electric fuel pump operation

Verify that the pump doesn't work (listen for it at the tank as an assistant turns the ignition switch on (do not crank the vehicle), it should run for about 2 seconds. If you don't hear it running, tap on the tank (within the 2 second run time), sometimes this will get it going.
If it still doesn't work, check fuel pump fuse and relay (should be able to feel/hear the relay click when the ignition switch is turned on. Replace any faulty parts found. If everything checks out so far,
Disconnect the wiring connector at the fuel pump and use a test light to check it for voltage when the ignition switch in turned on. If power is there and yet the pump doesn't work the pump is bad.

All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.

Every engine requires spark, fuel and compression to run. That's what we have to look for.

These are the basics that need to be tested and will give us the info required to isolate a cause.

1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.

2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.

3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.

4) If all of these things check good, then you would need to do a complete compression test.

Once you have determined which of these functions has dropped out,
you will know which system is having the problem.