I just put an amp and subs in a '96 Grand Cherokee Laredo tonight. When, I went to start the truck, I hear the familiar clicking of a dead(almost) battery. So I throw on the charger and let it run for a bit. Go to start it, and the engine would just crank and crank, but not fire. Went on like that for a bit and then I just gave it some gas while it was cranking. It started, but wouldn't idle. As soon as I took my foot off of the gas, it would die. So the battery goes dead again, and I put it on the charger again. When I take it off, it starts right up just fine. Has anybody ever had this happen? Any ideas what could be the cause or the solution? Thanks.
If the battery has been neglected- corroded terminals, low fluid, top dirty, etc., I'd replace it and start from there. Otherwise, you need to find the cause of it being drained. You can do this with a multimeter. Turn all accessories off, make sure no lights are on (dome light, trunk light, under the hood, etc.). Set the meter on the highest current setting, and make sure the probes are plugged into the proper slots on the meter. Disconnect the negative battery cable, and place your meter in between the cable and battery terminal. It should read less than 50 mA or so. Switch to the next lower setting until you get a reading.
As far as the starting problem, I bet you've either got a restriction to the fuel system (possibly clogged filter/injectors), or your pump may be getting weak. It doesn't seem like an electrical problem. If you're not sure when the last time your filter was replaced, start with that.
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My ex once told me I have a perfect face for radio.