Mechanics

WON'T START WHEN HOT

1996 Mazda b3000

Engine Performance problem
1996 Mazda B-3000 6 cyl Two Wheel Drive Manual 150,000 miles

History: This truck has been an excellent truck for 10 + years with no problems. About 2 months ago I received a P0340 (CAM Shaft Sensor) and couldn't get to it for about a month. I replaced the CAM sensor and the error code cleared initially but within a few days the P0340 returned. Since I had just replaced the CAM sensor, I was confused but after removing the sensor from the engine, I used a flashlight and a mirror to look down into the CAM shaft synchronizer assembly. I found that the metal vane that rotates through the hall effect sensor was completely destroyed (and then I remembered that when I had replaced the CAM sensor assembly, the sensor itself was destroyed as well. So, because I wanted to get the timing set correctly I took the truck to a local FORD dealer and had the synchronizer assembly (" distributor" ) replaced.

The check engine light cleared but the engine was still pinging and occasionally misfiring when going up hills and when I needed to shift to a higher gear. I also noticed that I was burning a lot of gas...

Then about 2 weeks later, my check engine light returned and this time it was a 301 (#1 spark plug). This one was easy, so I purchased a new Bosch plug and installed it. (I had replaced all the plugs and wires about a year ago). When I replaced the plug, I didn't see anything wrong with it, slight carbon buildup but that was all - no fouling at all...

After replacing the spark plug, the check engine light cleared and has not returned however, the current symptoms and the subject of this post is:

When I start the engine cold, it has a slight bit of difficulty starting but generally starts on first attempt and idles " OK" a little rough. But, when still cold, it hesitates and " coughs" in 1st gear until I get going (2nd gear) - (the hesitation is engine related, not transmission) Once I get past that initial cold rough running the truck runs great, has power, accelerates with no hesitation (it still lacks a little power when starting from a dead stop - I have to give excessive gas and baby the clutch) -

and all of that brings us to this... After running the truck for 15-20 minutes, stopping, turning the engine OFF (like to go into a 7-11 to get a cup of coffee - 5 minutes MAX) when I try to start the truck, it turns over fine but will not start. If I wait 8-10-12 minutes, it will finally start, hard idle at the very first and then it runs great.

Today when this happened, I remembered that the last time it happened and I was finally able to get it started, it was after I had turned the ignition switch all the way to OFF before trying to start it again. When I turned the key to OFF before starting today, it worked again and started 1st time... Go figure!

One last thing: After GOOGLing these symptoms I found a post from a guy who had very similar misfiring symptoms except he had problems with his #2 cylinder/plug. His later post said he found the problem was his fuel injector. So I donned a stethoscope and monitored the #1 fuel injector and it was clicking strongly like it was supposed to (no proof it was getting gas, but it seemed to be operating correctly). I treated the intake throttle with Sea Foam and sucked about 1/3 pint through the fuel system via the intake... Also added treatment to the tank. Now, I'll wait and see.

Have checked all vacuum hoses, replaced a few...
New air filter...
New battery cables and post connectors...

Sorry for the long POST but, I figure the more info the better!

Thank you for looking into this for, I appreciate it.

Dave
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Williamsd
July 27, 2008.



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