problem with my IAC again i think?
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Lead Driver
Joined: Nov 2008
Posts: 8,450
Likes: 70
From: South Jersey
problem with my IAC again i think?
a few days ago i posted in the 5.4 forum and got a few posts backs to check for vacum leaks and fuel pressure. problem is last summer i got stuck out on the river fishing one night and this dam truck couldnt spin a tire in high or low range. and stalled everytime i gave it gas to try and rock it out. so you guys told my to replace the IAC which i did and it got alot better but a few months later i was hunting and almost got stuck but the rpms would drop to 500 but come back up. but the truck still had that no power thing going on like it couldnt spin the tires. so the next day i took the truck to a shop and had 4.30 gears put in it. problem fixed no more problem spinning tires now. but the truck still acts funnny sometimes when i first start it, it jumps to 1200rpm slowly goes down to a normal 700rpm but sometimes it drops to like500 or even lower almost stalls and jumps back to 1000 and finally settles at around 700. so last june a new fuel pump went in (a factory one), i change the fuel filter once a month always, and a new IAC last june also but it was a aftermarket one. so i really need some help again cuz i love this truck but this little problem is really starting to get to me. oh by the way on the strret the truck is fine no problems anywhere in the power range but on occasion also when you first start to move from a red light the truck seems to hestitate for a split second and then move. if that has anything to do with it maybe.
Thread Starter
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Lead Driver
Joined: Nov 2008
Posts: 8,450
Likes: 70
From: South Jersey
218 people viewing this forum and no one has any idesas for me? please i really need some help since no one around my area knows, all i get is we charge so much an hour and call to schedule service
FTE Leadership Emeritus
Joined: Jul 2002
Posts: 42,561
Likes: 423
From: Long Island USA
Well, you have to give us longer than 3 hours, especially with all that you've already done 
Did you ever check the fuel pressure regulator?
Hook up a fuel pressure gauge to the fuel rail. At idle, you should see 28-30 lbs. Now, disconnect the vacuum line going to the fuel pressure regulator and plug it with your finger. It should jump up to 38-40 lbs. If the readings are way off, you probably need a new regulator.
Did you ever check the fuel pressure regulator?
Hook up a fuel pressure gauge to the fuel rail. At idle, you should see 28-30 lbs. Now, disconnect the vacuum line going to the fuel pressure regulator and plug it with your finger. It should jump up to 38-40 lbs. If the readings are way off, you probably need a new regulator.
