Fluctuating voltage at cold start
I will see if I can describe this and have it make sense. On cold startup, to voltage gauge will drop down to about 1/4 up on the voltage gauge when the glow plugs are on. After wait to start light goes off, I start the truck and it starts with no problem. After the truck is running, the voltage gauge will begin to rise up to its normal running location (about 2/3 on the gauge). After a couple of seconds of running, the voltage gauge begins to jump around from 1/2 to 2/3 on the gauge and will do this for a few seconds, then will return back to normal position. There is a slightly noticible difference in engine tone when it is jumping around. The truck has 2 brand new batteries, a new valve cover gasket and one new UVCH because one of the glow plug circuits was fried. I have ohm tested all of the glow plugs at the top side of the harness and all came up at 0.7 ohms. It also has a new alternator, and appears to have a newer GPR. My questions are:
Should it take a few seconds to get up to normal voltage after the truck has fired up? I am used to seeing the voltage gauge jump right to its normal reading immediately after the truck has been started (this has been my experience on my other powerstrokes).
Is this jumping around of the voltage gauge the glow plugs cycling on and off? I thought when they cycled on and off they would stay on for a few seconds then turn off and back and forth. This voltage fluctuation is about every second.
If this is how the glow plugs cycle, should there be such a draw that I can see it on the voltage gauge when the truck is running?
If I need to make a short video, I can do it if I didn't make sense with my description above.
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