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sprinkles08, ASE Certified Technician
Category: Car
Satisfied Customers: 23005
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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Mazda MPV: While Im driving down the road my RPMs will fal

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While I'm driving down the road my RPM's will fall to zero. Sometimes if I push the gas pedal all the way down the engine will recover, other times it stalls and I have to stop and restart the car. This usually happens as I am starting after a stop, although it has happened three times at speed. It never happens when the car is just idling. What is causing this problem, and how do I fix it?

Hello and welcome to JustAnswer!


If the tach is falling to zero yet the engine is still turning (albeit not running) then the most likely cause for that would be a bad crankshaft position sensor. The crank sensor is internal to the distributor on this model and tells the engine controller the location and speed of the distributor. If it's signal drops out then you will lose spark and the tach will fall to 0 even though the engine is still turning.


It could also be the engine controller itself going down, in which case I wouldn't expect a fault code to be stored. The first thing I would recommend is checking for codes and it's likely that you'll have a crank sensor code stored.

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Customer: replied 4 years ago.
How do I set my new distributor so that my engine will turn over? I threw the old one out.

I'm a full time tech and at work this morning, I'll get back to you as quickly as I can!


Customer: replied 4 years ago.
No worries. Thanks for the help.

You're welcome!


Customer: replied 4 years ago.
Just filling this in so the system thinks I gave you more information
When you installed the distributor did you bring the engine to top dead center on the number 1 cylinder and then set it so the rotor was pointing at number 1?

Has the engine been turned while the distributor out?

Or have you installed the distributor and it's not correct and now the engine won't start?

Customer: replied 4 years ago.
No I didn't bring the engine to top dead center. I just installed the distributor and now the engine won't start.
Look just above the crank damper and a little to the engine's right and you will see the timing degree marks on the timing cover. Turn the crankshaft by hand until the line on the crank damper lines up with the 0 or T mark on the cover.

Remove the distributor cap. Find the number 1 plug wire terminal, flip the cap over and look inside to trace out where the number 1 wire terminal is inside the cap. Mark this location on the distributor body.

Remove the distributor and reinstall it with the rotor pointing to your mark.

Then see if the engine starts. This will either put the distributor in the correct position or it will be 180 degrees off.

If it doesn't start then put the engine back into time and remove the cap again, look at the rotor. If it's pointing to the number 1 mark then remove the distributor, turn the engine 360 degrees and reinstall the distributor.

After you get it in place correctly and get it running then the ignition timing will need to be set using a timing light.
Customer: replied 4 years ago.
After changing the distributor I am still running into the original problem, the engine stalling while I'm driving. I have noticed a pattern however. Whenever I fill my gas tank up my engine won't stall for the first quarter tank I use. After a quarter tank of use the stalling starts and get worse the more gas I use. What could be causing this?
Does it die abruptly or does it hesitate and run out of power as it dies?
Customer: replied 4 years ago.
A little of both. Sometimes the rpm's fall off and the engine will recover if I smash the gas peddle down. Sometimes the engine will just die. But again none of this happens until my gas tank is down to about 3/4 full.
It may be a fuel pump issue. Do you have access to a fuel pressure gauge? What I would do is monitor fuel pressure and see if pressure is dropping off when this happens. If it's dropping off then it could be a loss of power or ground to the pump or the pump itself.