Hi all
I bought a 2003 Mazda B2300 it’s a 2.3L 16 valve engine. Not running. I towed it home and the next morning the truck fired right up. I drove all day, engine started no problem all day. The next morning back to no start.
The fuel pump will not prime and it has no spark. The engine won’t start even when spraying carb cleaner into the throttle body no spark.....
I’ve tried many things. Checked and replaced all relays and fuses attached tothe pcm and fuel pump.
I then replaced crank sensor w no luck, then decided to try the ignition switch, again no luck. Even changed the coil pack.
The pcm relay gets the constant 12v and gets power when key is on potions. So does the fuel pump relay two hot w key I. I have switched all these relays too
When hooked to my code reader I get an rpm so the crank sensor is sending signal. And it reads no saved codes or pending codes. The check engine light is on w key on and goes off while cranking so it seems pcm is good.
The pats system seems to be working fine too. Theft light flashes normal w key off then goes off while cranking. No super fast flashing. I have two keys and have tried them both.
I really need this truck running to get to work and back. Thought I’d be able to get this truck running thought I got a good deal but now am beginning to worry.

 

See if you can borrow a code reader, you have checked everything except the PCM, its good that the CEL comes on, that means PCM is booting up but it should also then run fuel pump for 2 seconds, and it is not doing that, so..........................

Maybe if you try reading the codes you would get a error so you would know PCM has failed, or you would get a long list of codes that make no sense, another sign of failing PCM

 

Hi Ron thanks for the response. I have a cheap code reader and it throws no codes and when it was running for that day no check engine light on.

 

Unplug MAF sensor or TPS(throttle sensor) or....ect and crank engine to see if CEL comes on and it sets a code, just a sanity check

 

Ok good idea. I’m at work but will try when Im home. I’ll get back to u early tomorrow. thanks again

 

So I’ve had maf sensor unplugged for like 5 days and have been periodically trying to start it. Unhooked the tps too. No pending codes. When my code reader is hooked up the and the mass air flow sensor is not it gets a -40 degree reading. As soon as it is hooked back up gets a outside temp reading so it seems fine. Throttle position sensor readings go up and down as I step on the throttle. The code reader is reading 275 rpms which seems normal for a cranking engine so it seems crank sensor is working.
How long would it take till it sets a pending code? Seems like the computer is reading everything normal.

What else could stop fuel and spark at the same time?

 

If I buy a new pcm is there a cheap computer I could buy to reset the security. Or is there a way to do it without a computer?