99SebringZ28

Sorry for the long read but I have a problem that I have been fighting for a while. I have done a lot of reading on here but did not see anyone with my exact symptoms. My 99 Z28 has a sporadic no start issue that I cannot seem to solve. About a year ago it would turn over but not start so I jumped it off and it started right up and ran fine. After I cleaned the terminals and decided they were not the problem I replaced the battery even though it was only about 3 years old. Everything was fine for about two weeks and then the problem reoccurred. I had the alternator tested at the parts store and it passed as well as the new battery. The battery cables were in rough shape anyway so I replaced them both but no change. Sometimes the car starts fine on the first crank and other times it just turns over with no fire. Regardless of whether it starts or has to be jump started it always runs flawlessly. I have had some success with charging the battery but not always. Once I tried starting it with a jump start box but it would not work, it required a car running on alternator voltage to start. You can hear the fuel pump run before starting and it shows good fuel pressure. I pulled a spark plug wire and tested it and it had good spark but once I reinstalled it the car started up so it may have just not been experiencing the problem at that time. Are there any relays/fuses or sensors that might prevent the car from starting on 12-12.5V but run fine on 14V? Has anyone experienced anything similar? Any guidance about what to check next would be great, I do not want to keep throwing parts at it.

Car Description: 99 Camaro Z28, 145K miles, Automatic, Stock LS1, Very minor wiring mods (High/low beams and fogs at the same time, added some LED’s, ect. But all were in place long before problem occurred), Not daily driven – maybe 2-3 times per week, No SES light or stored codes.

Tuskyz28

Mine is doing the same thing. I think the cold weather killed my new battery fast....

LS6427

iTrader: (2)

Did you check to make sure your PCM-to-Engine grounds are tight.....?

The bolts that connect to the back of the passengers side head...

.

99SebringZ28

I did not get a chance to check the ground last night. Could they find a worse place to put it? Is there an easy trick to get to it?
Thanks

wssix99

iTrader: (5)

If your battery was bad, you'd see a consistent issue. So, you defintiely have a battery charging problem. You can confirm this with a voltmeter the next time you have the issue.

If the car won't start and your battery voltage is low, then you have a charging problem.

If the car won't start and your battery voltage is fine, then you have a wiring/ground problem.

Charging problems are more complex. A bad alternator can still test "good" at the parts store, but the first culprits to check are for wiring/ground issues and also your belt and tensioner. (If your belt is slipping, you could also have charging issues - but you should also see the effect of this on your gauge cluster with a low voltage reading while you are driving.)

jimmy92rs

I would Check the battery ground and chassis ground for looseness and corrosion first.

LilJayV10

iTrader: (39)

You need to check for voltage drop on the positive and ground side of the starting system with the system loaded. If there is a connection, corrosion problem using a voltmeter to check battery voltages and ohming wires will not reveal if there's a problem.

Motopilot

This may or may not help you, but it is at least worth mentioning. When my starter started to go out, It would crank on a new charge or when Jumped, however normal or a little low battery voltage would not turn over. Eventually, it stopped altogether. If you think this is even remotely plausible, I would at least have someone check it, or do it yourself. They did mine for free at AZ.
Hope it helps, Motopilot

99SebringZ28

I did consider that it may be the starter but I am not sure how to test it. Does it have to be removed?

99SebringZ28

It was the ignition relay. I had tried switching with one of the fan relays previously and it did not help but I thought changing one fifteen year old relay for another may not be the best way to test them. I picked up a new one from the parts store for a few bucks and the next time it would not start I changed it and it fired right up and has been fine since then.