rough start up

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Sep 6, 2014 | 02:06 PM

59203shop

Thread Starter

Mountain Pass

Joined: Apr 2012

Posts: 196

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rough start up

hey guys, I got a 2002 ford explorer. what causes a hard start, rough start? it almost starts been then shuts off right away. and then when you restart it, it starts right up and runs. sometimes the very first time you try to start it, it would crank crank crank and crank, and then I would stop, and try it again, it will fire right up. what the heck? no codes...what could it be?

Sep 6, 2014 | 09:47 PM

Mikeman

Posting Guru

Joined: Apr 2000

Posts: 1,746

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From: PNW

Try turning the key to ON (not START) until you hear the fuel pump stop at least five or six times before you turn it to START and see if it starts up right away. If it starts right away, it would suggest a leaky check valve in the fuel pump. You can do a more thorough check with a fuel pressure gauge. Hook it up and see if there's pressure when you shut the engine off and after it has been sitting overnight. Then, check to see if pressure builds up when you turn the key to ON. Keep turning the key to ON and check for pressure increasing each time.

Does it run smoothly once it starts? Any black smoke when it first starts up? If there's a puff of black smoke like it's running rich, it could be a leaky injector. A leaky injector is pretty rare. They seem to last forever.