Buzzing sound after shutdown
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Buzzing sound after shutdown
'88 F150 4.9
The buzzing in the video continues for a couple of minutes after the truck is shut off. Coming from the EGR area. Unplug/replug the EGR vacuum line and it changes pitch (even thoughh the truck is off and the key is out). Eventually it winds down like an electric motor would sound but it is not the fuel pump or the blower motor.
I have recently been troubleshooting the usual 4.9 EGR bucking at road speed and a surging/stalling idle issue on cold mornings.
The buzzing in the video continues for a couple of minutes after the truck is shut off. Coming from the EGR area. Unplug/replug the EGR vacuum line and it changes pitch (even thoughh the truck is off and the key is out). Eventually it winds down like an electric motor would sound but it is not the fuel pump or the blower motor.
I have recently been troubleshooting the usual 4.9 EGR bucking at road speed and a surging/stalling idle issue on cold mornings.
Cargo Master
Joined: Jan 2004
Posts: 3,118
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From: South Dakota
That's kind of exclusive to 4.9 engines of a very few years around that time. Some kind of fan is supposed to cool something after the engine is shut off. Something with the fuel system I believe. Anyway it is supposed to do that.
I think the one on my '88 played out, i don't remember hearing it anymore.
I think the one on my '88 played out, i don't remember hearing it anymore.
Postmaster
Joined: Nov 2011
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From: SW Florida
That's kind of exclusive to 4.9 engines of a very few years around that time. Some kind of fan is supposed to cool something after the engine is shut off. Something with the fuel system I believe. Anyway it is supposed to do that.
I think the one on my '88 played out, i don't remember hearing it anymore.
I think the one on my '88 played out, i don't remember hearing it anymore.
Junior User
Joined: Jul 2007
Posts: 55
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From: norfolk, va.
Look for the blower on the pass. side of motor. Look for a flex hose coming from blower to a manifold going under your intake runners. Next time you hear the noise, un plug blower and see if it stops. Mine sounds more like a fan than a buzz. Worth a check.
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Sorry guys, should have mentioned that fan has been disconnected for years from the looks of it. No, this seems to be coming from the electrical/vacuum do dads bolted to the head right under the EGR valve. Ive been grabbing sensors from the local pull a part (for almost free) to diagnose my idle problem. I'll get a set of these next time.
Post Fiend
Joined: Apr 2004
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From: Lafayette, IN
My '93 F250 did it, too, as did my '90 F150, if I recall. I think it's probably just the vacuum reservoir slowly filling with air from one or more of the vacuum-controlled components leaking ever so slightly.
Jason
Jason
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Fleet Owner
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My old 1992 F350 made a "farting" noise after shutting off the engine. I traced it down to the EGR Valve Regulator (EVR). I took it apart and cleaned the filter, that seemed to lessen the noise
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On further inspection it is definitely the egr vacuum regulator solenoid. I can feel the vibration in my hand. I am a bit concerned as to why it would be trying to operate with the key off. I've pulled the computer and replaced the capacitors but that had no effect on anything.
Post Fiend
Joined: Apr 2004
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From: Lafayette, IN
On further inspection it is definitely the egr vacuum regulator solenoid. I can feel the vibration in my hand. I am a bit concerned as to why it would be trying to operate with the key off. I've pulled the computer and replaced the capacitors but that had no effect on anything.
Jason
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TexasGuy001
1987 - 1996 F150 & Larger F-Series Trucks
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Jan 2, 2005 06:12 AM