Engine won.t turn

First pull a spark plug and have someone turn over the engine to see if you have spark. Make sure the plug is grounded. IF spark it may be a fuel issue, and most likely a fuel pump. If no spark, Could be a bad ground, check the battery cable to engine, black for ground, make sure no corrosion, clean and ret-torque fastener. Next check that no fuses are blown. Follow the positive feed to the distributor, make sure that you have power to the distributor coil. YouTube is a great place to see if there are checks for diagnostics. You will need a volt /ohm meter to check for power and continuity. Sorry for the generalities, but you should start from the power source and

Hi Mark
Sounds like you are doing all the right things.
We used to Load Test a Starter Motor by putting it in a Large Vice and connecting a known good battery with solid fat jumper leads.
When the solenoid throws the cog forward to engage we would use a 2 by 4 block of wood levered against the cog to try and stop the starter from spinning. The wood burns up under load but it quickly proves the Starter is functioning under load. Without using the engine.
Also you could try removing the spark plugs on the engine to allow the compression to escape. Make sure NO sparks around to ignite any fuel vapor.
The engine should spin over easily like this and you can hear & see if anything is binding up.
Hope this Helps!
Good luck!

Check for spark at plugs, fuel pressure, compression test to see what area is failing.

There are three basic items that make a car engine run - ignition, fuel and timing/compression. If any of these are missing or bad, the engine wont start.
To check for ignition, pull out a plug wire (any one) and place a metal object such as a smallish screwdriver into the plug cap, hold the metal part of the object near a metal part of the engine then have someone (the trouble and strife will do) turn the engine over.
If the ignition is OK, a nice blue spark should pop from the metal object to the engine. Keep your hands away, the spark reaches upwards of 26 000 volts, not enough to kill you, but it can spoil your moment.
To check for fuel, remove the fuel line from the carburettor and turn on the ignition for a second. A good stream of petrol should spurt from the pipe if you have an electric fuel pump, otherwise crank the engine to let the mechanical pump work.
Finally, check for compression. Remove a spark plug, block the plug hole with a finger if possible, then have someone crank the engine. The compression should attempt to blow your finger out of the hole. Compression is dependent on good timing. If the compression is bad, you could have a broken timing belt, a blown head gasket or a number of other nasties.

It would be much easier to turn the engine by using a socket and a breakover on the crankshaft pulley bolt. I understand why you thought you needed to turn the engine. If you remove the spark plugs it will turn real easy because you don't have to fight the compression. Are you sure the battery didn't die on you? What year is your truck, and which engine do you have? Was there a trouble code that let you know the ecm was bad?

If it over heated, could have bad head gasket's, fill radiator with water, crank engine with radiator cap off, if water is push out of radiator while cranking, bad head gaskets', also remove spark plug's, crank engine if any water, bad head gasket, also when spark plug's removed, check for any water on them.If there is any water on plug's, bad head gasket, also could try doing a cylinder compression test, if bad compression, head gasket, no compression, wont start that way.

FIRST OF ALL YOU NEED TO RUN ENGINE FEW MINUTES DONT GET IT TOO HOT. TURN OFF ENGINE. THEN PUT ON SAFETY GLASSES. USE COMPRESS AIR BLOW DEBRI AWAY FROM SPARKS PLUGS.TO KEEP FROM GETTING INTO CYLINDERS.DISABLE YOUR SPARK IGNITION.AND DISABLE FUEL PUMP.BY REMOVING FUSE.NUMBER AND TAG SPARK PLUG WIRES.REMOVE ALL PLUG WIRES AND SPARK PLUGS.BESURE YOU NUMBER THEM AND TAG THEM SO THEY GO BACK IN THE ORIGINAL PLACE.THEN GET COMPRESSION GAUGE TESTER SCREW IT IN SPARK PLUG HOLE TO CYLINDER 1 FIRST.TAKE YOUR FOOT PRESS ACCELERATOR PEDAL TO FLOOR.PUT KEY IN IGNITION SWITCH CRANK ENGINE AROUND A FIVE TURNS.THEN CHECK COMPRESSION ON GAUGE.IT SHOULD BE NO LOWER THAN 100 PSI.IF SO SQUIRT SOME OIL IN THAT CYLINDER. IF COMPRESSION INCREASES.THAT CYLINDER HAS BAD RINGS IF OIL SQUIRT DONT INCREASE COMPRESSION. VALVES IS LEAKING. YOU DO ALL CYLINDER THE SAME.SCREW COMPRESSION IN PLUG HOLES.TURN ENGINE OVER 5 ROUNDS. WRITE DOWN ALL READINGS.

this is common,it is flooded,Mazda has a concern with this model and a dealer may install a new motor if the compression is down

Sounds like your starter is going out once you replace your starter your truck run better

if the starter is revving very slowly it is the battery, charge battery. if not, It can be three things happing. 1 no spark 2 no fuel 3 no crank signal or the car computer is bad- you will need to unplug one of the spark wires and remove the spark plug and put the spark plug in the spark plug wire boot, and touch the spark plug on any metal on the car and have some start the car. donot touch the spark plug itself and see if there is a spark. if spark is bright, then it is not spark plug and wires but if no or spark is not bright, check the spark plug wires by applying a little bit of water on the spark plug wire and take a 12v test light, connect the clap to ground and and have some one to crank the vehicle, touch allover the spark plug wires with the tip of the test light, if you see spark, replace the wires and change the plugs.. they are not good. if spark is present, check for fuel by removing any one of the spark plugs and see if it is wet. if wet fuel pump is ok but if not go look for the fuel pump fuse and relay. is fuse blown, replace, check the relay resistor with a volt meter. it should be around 40 to 80 ohm. if everything is good from this point check the fuel pump itself by disconnecting the connector to the pump and apply 12v and ground using jumper wires or some wires to the fuel pump if you donot hear the pump,replace pump. if you, the crank signal or computer may be the problem