My truck wouldn't start today, battery had some power but not enough. Charged it for a couple of minutes (using an engine crank mode) and it started. Let it run a few minutes and moved it to finish my weekend project of cleaning it. Couple of hours later it wouldn't start and I had to use the charger again.

Waited about 30 minutes and it started fine but when I shut it off, I heard a strange noise under the hood. Started and shut it off again and traced the noise to under the plastic throttle body cover. It's a hissing/crackling sound lasting 5-10 seconds after the engine is shut off.

My first thought is that the battery needs replaced. I'm guessing it's the original. However the battery light has not been on and currently is not on and I'm concerned about what the strange noise means.

 

Just tried it again and the truck started fine plus the strange noise did not occur. Could the noise have been part of the computer control system readjusting things itself after the battery's initial loss of power?

 

have had my 98 4.6L 4x4 flaire-side (1st owner) 45,000 miles.

it has always made a hissing noise right after shut down, comes from the right side of throttle body. figure it's the fuel rails relieveing pressure. or just engine vaccum.

 

whoops strike that my truck has 65,000 miles on it. and it's never given me a problem till 60,000 when it started the ping thing like every body else.