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Old 11-23-2007
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Join Date: Oct 2007
Location: Idaho falls, ID
Posts: 2
hard starting

HI every one!

i have a 99' Ranger, 4.0 that has a hard time starting when the outside temp is below 30 degrees and it sits for several hours. I have replaced the battery and cables, iac, iat, ect, fuel filter, cleaned the maf, changed the plugs and wires, and lower intake gaskets, had the coil tested. it will start and idle realy rough for 10 to 20 seconds and is fine after that. My mechanic tested the pressure for leak down and stuff and said it is fine, but he never had a hard time starting it. ( it was in a garage) Could the pressure regulator be causeing low pressure only when it is cold and it is haveing the problem? I cant hear the pump prime for 2 sec. should you beable to for sure with this model? I dont hear it when it is running either however. Some times when its really cold out it will start, sputter and some times die. on restart she fire right up. Once in a while it will start rough when it is warmer out ( low fifties) it seems like its always moist out durring that instance. thanks to all.

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Old 11-23-2007
4LO 4.0's Avatar
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Join Date: Jun 2007
Location: Grovetown, Ga
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Try running a can of sea foam through the motor.
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Old 11-23-2007
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Welcome Mike, Looks like your already on top of the most common stuff.

The only thing I'd try to rule out before digging deeper is to see if it's getting spark at first fire. (I'n not sure if the pcm is holding back spark to allows oil to get primed or something? I say this because everytime since mines been brand new.. mine seems to take longer to start the colder it gets outside. When temps are in the 0 range you'd think something is wrong)

Last winter when mine was still under 10k miles I was thinking it was taking too long and considering taking it back to the dealership. Well.. I cleaned the injectors w/techron and started using shell V-power fuel. I was supprised! Within 1/2 a tank it started quicker and quicker. Still slower than in summer weather.. but it did make a difference.

Since your truck stumbles after it starts... I suspect it's fuel related. Maybe a leaky injector or low fuel pressure.

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Old 03-08-2008
Join Date: Mar 2005
Location: Whitehorse, Yukon
Posts: 30
hmmmm interesting thread.


i just did an engine on a 97 F150 with the old 4.2. the truck was a $500 junkyard find by our client as it had a siezed engine. we did everything ... rebuilt block and heads, reman injectors, reman starter, reman alterternator, water pump etc etc etc. the only used parts on the truck, generally, were the front end, rear end and the tranny. everything else was done.

after we did the swap we had a hard time starting it. every start would flood the engine. the only thing i could do to get it running was to pull the plugs and dry them off. with that i did the cold start sensor and things sorted themselves out - for a while.

the truck is still at my shop as the cold start issue (and winter, lol) wont go away. leave the truck inside overnight at it starts like a champ. leave it outside in the cold for a few hours and it still wants to flood itself upon startup. and when it does start when cold, the idle is rough. no check engine light and no misfire.

i'm leaning toward the regulator on the fuel rail on this F150, and that might be something to check out on your truck too.


With that F150, if an injector were leaking down then:
- only one plug should be wet when pulling plugs
- it should flood the engine when it's warm, too

For both your truck and the F150 it sounds like it might be that regulator. The cold will do funny things sometimes.
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