I have recently started working on my 87 RX7 n/a. The car has set for years but I finally got it up and running it starts perfect when its cold but after a drive and after it sets for about 20-30 mins it wont start with out boosting off.
It will crank but once a booster box is connected it fires right up and starts just as good as it does when cold.
The volts gauge shows 14v when idling but the battery ranges between 87-95% according to my maintainer after a short drive.
Once boosted it will start back no issues even with out connecting the battery to the maintainer.
Could the alternator be going bad? Or possibly bad or loose belts?


Any help would be awesome!

 

Have you tested the battery? Have you tested for output voltage from the alternator? These are two places I would start. Have you checked the battery terminals to ensure they were clean and tight? Does the engine crank slower hot than when its cold?

 

The battery is brand new and resting voltages are mid 12's the voltage measured with multi meter at idle the alternator is putting out 14.4 cold (I have not checked it warm)
I have not had my meter with me to check the battery voltage when it doesn't want to start. The battery terminals are clean and tight as well.
Yes it seems to crank slower when it is hot versus being cold.

 

That's all good info. Have you checked the connections on the starter to make sure the power wire and signal wire are clean and tight? Also, make sure the negative cable is properly affixed to the trans. Remember, the grounds are extremely important and that the grounding is achieved through the threads, so ensure the bolts that secure the grounds are clean and ensure the threads on the nuts that are welded to the body are clean as well. You also want to make sure the terminals being grounded are clean and free of any corrosion as well.