rough idle at start up
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rough idle at start up
I have an '87 f-150, 4.9L Inline six, 4x4 which is idling rough when you first start it up. It will drop real low in RPM's and then jump back up and then down right away. It does this about three or four times and then idles ok, but still alittle rough.
I just replaced the rear gas tank and sending unit right before it started doing this. Before starting it up I turned the key to on and crawled under there to make sure nothing was leaking, and noticed the vent tube off the top of the tank was not sealing properly to the metal tube it connects to and I could hear a hissing noise and could smell gas vapor. Nothing is leaking in the fuel lines. However it hasn't been started in about a month and a half due to my being away for work.
My first thought was a vacume line or something of that sort but then it stopped acting up after about 30 seconds.
Any help would be greatly appreciated.
David
I just replaced the rear gas tank and sending unit right before it started doing this. Before starting it up I turned the key to on and crawled under there to make sure nothing was leaking, and noticed the vent tube off the top of the tank was not sealing properly to the metal tube it connects to and I could hear a hissing noise and could smell gas vapor. Nothing is leaking in the fuel lines. However it hasn't been started in about a month and a half due to my being away for work.
My first thought was a vacume line or something of that sort but then it stopped acting up after about 30 seconds.
Any help would be greatly appreciated.
David
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Joined: Feb 2003
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From: Muskegon, MI (home)
My experiences with this brought me to replacing the IAC (idle air control valve) on my 96 F150 300 six. Now she runs smooth and steady as ever, I have also heard of the TPS (throttle position sensor) causing this. Are you getting a "Check Engine" light coming on?
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had some time to start her up again today and there is no check engine light. Something I forgot to mention is that the air injection was not connected when i bought the truck and I reconnected it since the last time I started the engine. I don't know if that would affect it or not.
Fleet Owner
Joined: Jan 2008
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From: southern md
if you have a way check the engine codes-it can be done with minimal tools -there is a link on here somewhere how to do it with out a scan tool-I think if ya look at the top of the page 1st column it's in that thread -the read 1st thread on here!
how to check engine codes
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Thank you for that information. I dont have time to do that right away as I have to put all new brake lines in the truck because when I went to take it for a drive the brake pedal went all the way to the floor and I discovered a pretty big hole in one of the brake lines. Good thing I had not left the driveway before this happened.
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