Glow Plug Question

[Snowman671]

Just a quick one,

Once I turn key the WTS Light comes on, amp metter drops to about 8 or so 20 seconds later WTS goes out then start truck. now if I watch ampmeeter it does liek a clock 8 the 12 8 then 12 8 - 12 jumps up and down for about 20 more seconds ...

Is this normal or is something out of whack here. I think it keeps cycling the glow plugs on and off eveyr 2 seconds after I start for at least 15 or 20 seconds.


Thanks
Dave

 

[The Warden]

Sounds normal to me, depending on the interval. The WTS light comes on until the glow plug controller thinks the engine's warm enough to start, and can cycle the glow plugs a few times before turning the WTS light off.

But, if it's cycling on and off every second or two, you might have a glow plug out...

How's she starting?

 

[EvergreenRanch]

its bobbing like that after the engine is running? thats not normal as far as i know....id get a voltmeter on your system stat to see if your system is really spiking that much or if its something more innocent. if everything is kosher....gotta find out whats either causing that much of a draw :draw , or why the voltage is dropping that quickly.

 

[pafixitman]

That sounds like mine. The plugs cycle a bit after she starts, has since the day I fixed the 7 burnt out glow plugs. I would watch the dome light before I added the volt gauge.

 

[jslash]

As I understand it, that is normal. It keeps cycling the glow plugs for a few seconds after the truck is started to help it warm up.

Jim

 

[f-two-fiddy]

its bobbing like that after the engine is running? thats not normal as far as i know....id get a voltmeter on your system stat to see if your system is really spiking that much or if its something more innocent. if everything is kosher....gotta find out whats either causing that much of a draw :draw , or why the voltage is dropping that quickly.

This is perfecrly normal. It can 'After Glo' for up to 2 minutes. Usually it only afterglo's for a min or so, depending on how cold the coolant is. I can actually hear my truck quieting down during the afterglo cycle.

 

[EvergreenRanch]

i humbly withdraw my comment. i just havent observed those type of voltage jumps after im up and running. maybe its just this california weather..... i havent had to start the engine in temps under 50*. sorry fellas ill check my facts before i jump in next time.

 

[F350camper]

not to -Deadhorse but this is what the ford manual says about the GP system. Again, this is normal behavior.

Glow Plug Fast Start System

The 7.3L diesel engine utilizes a solid-state glow plug system to aid in the start of the engine. The system pre-heats air in the combustion chamber to aid ignition of the fuel.

The system consists of eight glow plugs (one for each cylinder), a solid-state glow plug controller/power relay assembly, two fusible links located between the power relay and the glow plug harness (one for each bank of four glow plugs), WAIT TO START lamp and a wiring harness which incorporates eight fusible wires (one for each glow plug).

CAUTION:
Hard starting will result if the ignition switch is left on for over two minutes without starting the engine. If the ignition switch is turned off, it can be turned on immediately and the glow plug heating cycle will start again.

An after-glow operation allows the glow plugs to cycle on and off after the WAIT TO START lamp has turned off. This helps to reduce white smoke during engine warm-up. The lamp will NOT cycle on and off during this operation.

The solid-state system determines the glow plug temperature by electronically measuring the resistance of the glow plugs and maintains temperature regardless of ambient conditions. The system uses positive temperature coefficient (PTC) glow plugs with push-on bullet terminals. These are NOT interchangeable with previous model year glow plugs.

 

[Snowman671]

Well I'll be darned somthing that might actually be workign correctly. I have replaced all 8 with the recommended glow plugs. (Motorcraft) so i'm happy about that. I think i may need to do a bit more. it was 82 degrees yesterday and of course they kicked in for thier normal 20 seconds before it would let me fire it over.

Another thing after the engine is warm shoudl it still cycle for 20+ seconds everytime. I mean i can shut her down go in store come back out in 5 - 10 minute snad blam gotta wait that whole cycle again is this normal or is there sensor might need replaced.?


Dave

 

[aaklingler]

that doesn't sound right, 5 sec. on a warm engine at 82* should be plenty.

 

[pafixitman]

Dave,
IIRC, I get the WTS cycle almost all of the time. She has to be very warm for me not to get the cycle. Of course, now that you ask I second guess my self and will need to pay attention to it!

I like the looks I get from my wife when I get in the Explorer, turn the key, wait and realize I am not in the truck!

Sent you a PM about Gettysburg.

 

[f-two-fiddy]

that doesn't sound right, 5 sec. on a warm engine at 82* should be plenty.

It is right, it's an emission deal with later model diesels. My 93 does it, my 85 doesn't.