5.4 Rough Start sometimes
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New User
Joined: Nov 2003
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From: Missouri
5.4 Rough Start sometimes
I have a 99 F150 lariat with 5.4 engine. I replaced the IAC over the winter because it would start and immediatly stall, replacing the IAC fixed the problem by the way. On to something that has been going on since I had the truck, but has began to knaw at me recently. When I start it up after its been warmed up, like drive 30 miles, shut it off, and in an hour come back and start it up. It starts, but sometimes it is really rough starting, like it misses while starting almost. But this only happens sometime, other times it is smooth and nice..but I always cringe when it goes south on me. I wonder if it is the fuel filter (crossing 150,000 miles tomarrow) and I don't know if it has been replaced. Also thought maybe MAF? but I don't knwo if the computer gets reading from the MAF on warm startup or after some post-startup interval. MAF also hasn't been replaced to my knowledge. After it starts up it is fine and idles just fine (it has that slight roughness but I like it damnit 
What would you guys start by looking at? Thanks! 
if you suggest fuel filter, how do I go about replacing it?
What would you guys start by looking at? Thanks! if you suggest fuel filter, how do I go about replacing it?
Mountain Pass
Joined: Nov 2003
Posts: 142
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I would definitely replace the fuel filter. It's located on the driver's side framerail just about behind the driver's door. You will need a disconnect tool that you can get at NAPA, Autozone, etc. Make sure you relieve the fuel pressure before starting by popping up the Fuel Inertia Switch (located on the passenger side footwell, just above the carpet). You can stick a small screwdriver under the little red button and carefully push it up. Then try to start the engine a couple of times (it'll die out from lack of fuel).
As for the MAF, check this out:
https://www.ford-trucks.com/forums/s...hreadid=126093
The link is for a 3.0, but the basic procedure is the same.
Hope this helps.
As for the MAF, check this out:
https://www.ford-trucks.com/forums/s...hreadid=126093
The link is for a 3.0, but the basic procedure is the same.
Hope this helps.
Last edited by mizzleman; Jul 12, 2004 at 12:27 PM.
Thread Starter
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New User
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From: Missouri
update
Well, before I read the post you left, I did just all that, cept I disconnected the inertia switch instead of raising the button, same effect I might add. The fuel filter seems to help a lot, I get better pickup with less gas pedal. So a good sign, I've driven it all day off and on and I havn't had a rough start yet, so here's hoping And thank you for the MAF link I'll be looking into that too, just cause. :-)
In the MAF section it mentioned that disconnecting the battery is very important, it said to do that in my chitlin book....but I didn't cause I'm lazy and I don't like things that could ground (ie spark) laying around when I'm messing with gas. By unplugging hte battery I could possibly reset the system and get even more umph for my buck?
And thank you for the MAF link I'll be looking into that too, just cause. :-)In the MAF section it mentioned that disconnecting the battery is very important, it said to do that in my chitlin book....but I didn't cause I'm lazy and I don't like things that could ground (ie spark) laying around when I'm messing with gas. By unplugging hte battery I could possibly reset the system and get even more umph for my buck?
Last edited by wolfdog1; Jul 12, 2004 at 05:44 PM. Reason: neg batt. disconnect?
