I didn't have enough money to insure my car so I let it sit for 5 months. I tried it today and it doesn't start. Does anyone know why?


Battery probably. Youd need a jumper cable from a running vehicle connected to your dead car then start it up.

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  • Don't have the donor car running - easy way to damage the alternator. – Solar Mike Apr 20 '19 at 19:30
  • @SolarMike - A running donor is the only way I've ever done it and I've never had an issue with blowing up the alternator. I've heard people state it before, but I've never read any authoritative source stating you shouldn't. Your jumper cables will melt before there's a feedback issue and your battery (on the donor side as well as the recipient side) is there and going to act as a buffer for any surges. – Pᴀᴜʟsᴛᴇʀ2 Apr 20 '19 at 20:33
  • @Paulster2 And that was the reasoning that many customers gave me as I was fitting them a new alternator. Simply, the very high instantaneous demand from the starter causes the alternator to try and match it - which can cause the diode pack to fail before the regulator catches up and controls (limits) the output and the battery on the good vehicle produces the power (slower due to the inherent internal resistance of the battery). Written this answer before so once someone proves it for themselves... It will be noticed as alternator4s are much mor expensive now... – Solar Mike Apr 20 '19 at 20:36
  • @Paulster2 Note it is not a feedback issue as you seem to think. Also, the initial current can far exceed the rated capacity of the jump leads - but you will need some good equipment to test that. We did that type of test with DSO's in controlled lab conditions. Like for an incandescent bulb the initial current can be 10 times the normal current flow once running. – Solar Mike Apr 20 '19 at 20:40
  • @Paulster2 So, see this : quora.com/Can-you-jump-start-a-car-while-the-engine-is-on – Solar Mike Apr 20 '19 at 20:50

So, first I would charge the existing battery overnight with a mains connected charger. Then I would test the battery to see if is still viable.

Then inspect the plugs and leads (clean and dry), water and oil levels, also if the gas tank is close to empty I would add a couple of gallons of fresh fuel.

Then try to start the car, if it starts then let it idle and warm up without driving it.

Then you should check the brakes, if they are disc brakes they may have some surface rust visible - if this is still light then driving with applications of the brakes will remove it. If heavy then taking the wheels off and cleaning or replacement will be necessary.

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