Let's Talk About Glow Plugs
Junior User
Joined: Dec 2013
Posts: 63
Likes: 0
From: Denver CO
So the GP system doesn't make any noise when it's energized correct? I'm dumb, I've been sitting in my truck waiting until the little humming noise goes away every time I cycle my GPs for a cold start (not plugged in). I turn key to on position (faint humming begins), WTS light comes on, then WTS goes off, I keep waiting until faint humming stops and I was considering that the GP system. Now I realize, there is not much that would hum in that system. So what is the hum?
Hotshot
Joined: Nov 2006
Posts: 11,286
Likes: 263
From: North of Greenville
The humming noise is your fuel pump which is located on the driver side frame rail almost right under your driver seat. It, like the GP's, starts every time your turn on the ignition and then runs for only a short time before shutting itself off (unless you either start the truck or turn the key off, obviously) - something like about 30 seconds, and that initial run time is always the same duration regardless of altitude, engine oil temperature, ambient temperature, etc.
NOTE... if it starts getting really loud (like a chattering noise), you most likely have a problem with restricted fuel flow to the pump or air getting sucked into the fuel line ahead of the pump.
NOTE... if it starts getting really loud (like a chattering noise), you most likely have a problem with restricted fuel flow to the pump or air getting sucked into the fuel line ahead of the pump.
Postmaster
Joined: Jun 2014
Posts: 3,206
Likes: 3
From: Oakhust NJ Jersey Shore
Don't forget to ohm each glowplug, disconnect the UVCH, the glow plugs are the bigger terminals, put one lead from your OHM meter to the negative battery or a good strong ground somewhere on the engine, then touch all 4 big terminals in the valve cover gasket connector, cold motor should have 4.6 ohms, on each glow plug +or - .5 ohms. if any are open or shorted you have to start there then move you way back to the relay, get rid of the IAH, that is nothing but a big plug restricting all your air to the intake, all that does is prevent smoke when you idle for long periods in the cold. Do yourself a favor and take that out and let the engine breath.
Laughing Gas
Joined: Jan 2015
Posts: 820
Likes: 3
From: Central OK
Don't forget to ohm each glowplug, disconnect the UVCH, the glow plugs are the bigger terminals, put one lead from your OHM meter to the negative battery or a good strong ground somewhere on the engine, then touch all 4 big terminals in the valve cover gasket connector, cold motor should have 4.6 ohms, on each glow plug +or - .5 ohms. if any are open or shorted you have to start there then move you way back to the relay, get rid of the IAH, that is nothing but a big plug restricting all your air to the intake, all that does is prevent smoke when you idle for long periods in the cold. Do yourself a favor and take that out and let the engine breath.
What is an IAH?
Some guesses:
Inner Apple House?
Inky Aardvark Hickey
Its All Hairy
Junior User
Joined: Dec 2013
Posts: 63
Likes: 0
From: Denver CO
The humming noise is your fuel pump which is located on the driver side frame rail almost right under your driver seat. It, like the GP's, starts every time your turn on the ignition and then runs for only a short time before shutting itself off (unless you either start the truck or turn the key off, obviously) - something like about 30 seconds, and that initial run time is always the same duration regardless of altitude, engine oil temperature, ambient temperature, etc.
NOTE... if it starts getting really loud (like a chattering noise), you most likely have a problem with restricted fuel flow to the pump or air getting sucked into the fuel line ahead of the pump.
NOTE... if it starts getting really loud (like a chattering noise), you most likely have a problem with restricted fuel flow to the pump or air getting sucked into the fuel line ahead of the pump.
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Hotshot
Joined: Jan 2011
Posts: 18,849
Likes: 179
From: Puget Sound
Air Intake Heater on trucks after E99. Two relays in the valley, the outer relay has a big wire going to the turbo spider. The AIH spins out with a wrench, and there is a sizable coil across the air inlet.
Postmaster
Joined: Jun 2014
Posts: 3,206
Likes: 3
From: Oakhust NJ Jersey Shore
Tuned
Joined: Oct 2012
Posts: 391
Likes: 8
So the GP system doesn't make any noise when it's energized correct? I'm dumb, I've been sitting in my truck waiting until the little humming noise goes away every time I cycle my GPs for a cold start (not plugged in). I turn key to on position (faint humming begins), WTS light comes on, then WTS goes off, I keep waiting until faint humming stops and I was considering that the GP system. Now I realize, there is not much that would hum in that system. So what is the hum?
