wnaplay1647545503 Posted July 29, 2013 Report Share Posted July 29, 2013 2007 dodge ram 5.7l. Bought 2 weeks ago and the truck probably sat awhile before it was purchased. No previous owner or mechanical history(bought at auction). Jumped it after purchase and truck has been fine all last week. I get in yesterday and just clicks. I jump it and go to gas station, won't start soi jump again and drive it to grove city. Come back a few hrs later and again I jump it. Come out this morning again I put charger on it and it immediately fires up as usual only after 2 mins of charge. I charge it most of the day and then drive to my inlays about 15 mins away. Come out 2 hrs later and it barely fires. As I am driving home it's barely able to move out of its own way. Get home and remove negative terminal it stays running. Shut it off and it fires right up but now it runs fine around the block. Do I have an alternator or battery issue most likely? Did the truck go into doe sort of limp mode on the way home or was that something else? Quote Link to comment Share on other sites More sharing options...
Browning Posted July 29, 2013 Report Share Posted July 29, 2013 battery would be my guess. Wouldn't hurt to hit both with a multimeter. Also, check the battery ground and the positive from the battery to the alternator. Quote Link to comment Share on other sites More sharing options...
Rocky31186 Posted July 29, 2013 Report Share Posted July 29, 2013 Sounds to me like a loose or bad connection somewhere. If your jump starting it and its driving fine I would doubt its the alternator.. But I would test it with a DVOM when its dead. On new cars do NOT remove a battery cable to see if it stalls. You can fry the PCM by doing that. Quote Link to comment Share on other sites More sharing options...
STEVE-O Posted July 29, 2013 Report Share Posted July 29, 2013 Simple battery test will show it is probably got a bad cell or is going bad. Check with a multi to see if your alt is outputting correctly Quote Link to comment Share on other sites More sharing options...
Cordell Posted July 29, 2013 Report Share Posted July 29, 2013 Sounds to me like a loose or bad connection somewhere. If your jump starting it and its driving fine I would doubt its the alternator.. But I would test it with a DVOM when its dead. On new cars do NOT remove a battery cable to see if it stalls. You can fry the PCM by doing that. This. Quote Link to comment Share on other sites More sharing options...
Not Brian Posted July 29, 2013 Report Share Posted July 29, 2013 Quote Link to comment Share on other sites More sharing options...
wnaplay1647545503 Posted July 29, 2013 Author Report Share Posted July 29, 2013 I started it this morning after jumping and instantly checked it with meter, I was getting around 14 amps or volts whatever it is on the battery with it running. The alternator does kinda sound like its whining. If the alt was bad wouldn't it have died when I disconnected it or would enough charge been in the battery to keep it going? Quote Link to comment Share on other sites More sharing options...
Browning Posted July 29, 2013 Report Share Posted July 29, 2013 Now that I think about it I had an issue similar to this with a new alternator on my old s10. When tightening the nut on the back I noticed I got it too tight and the stud would spin. Didn't think nothing about it but had random issues like this for a couple of weeks. Parts guy swapped it out after getting good readings randomly a couple of times. Was careful with the next one and the issue went away. Am I crazy thinking that the spinning stud was the issue or? Quote Link to comment Share on other sites More sharing options...
wnaplay1647545503 Posted July 30, 2013 Author Report Share Posted July 30, 2013 So I jumped it again today and took over to advance to test the alt and battery. Both tested relatively well but the battery kept saying needs charged. Again on the way over it felt like it was in a limp mode or was running out of fuel. I left the battery and they charged it but even then it said to charge the battery. Luckily the battery was replaced for free and at least on the drive home it seemed fine. Quote Link to comment Share on other sites More sharing options...
Akagis_White_Comet Posted August 10, 2013 Report Share Posted August 10, 2013 Starting/charging issues come up often when dealing with RX-7's, so the community came up with a simple way to test both while on the vehicle using just a voltmeter placed on the battery terminals. If you don't have one, go to Harbor Freight and get one $3. Engine off: 12.6v (Battery voltage when fully charged) Ignition ON (not running): 12.5-12.6v Cranking: 10.0v+ Engine running: 13.5-15.0v Under 13.5 when running means the alternator is dying or not connected properly. Over 15.0 means the voltage regulator has failed or is disconnected. Don't attempt to drive with a dead VR, you WILL fry the big, expensive parts like your ECU. My experience shows that 9 times out of 10, it is the alternator dying from being overworked. 86-88 RX-7s are especially known for this, and was the first issue I encountered, so my standard go-to cure is to hit the junkyard and grab one from a Pre-1996 Taurus or comparable Windstar with a 3.8L OHV engine. As for the remaining 1/10 of failure, it was from an Autozone battery dropping like a rock to 7.2v when cranking as it just had no grunt left in it. Car actually sounded like Lassie when cranking :lolguy: Replaced the junk battery with a Deka Intimidator and she fired up on the first try. Quote Link to comment Share on other sites More sharing options...
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