Hello guys it has been 80 degrees the last few days and nomatter if my truck is being started first in the morning or right after a 35 mile drive at 60mph the glowplugs stay on ten seconds, when the truck is warmed up they should only come on for 2 seconds I think, but there always on for 10, why is this happening? I don't know what to check such as the relay and controller someone please clue me in, the truck is great other than this and a small rear diff. leak

 

bump please someone help me out

 

There is some sort of thermostat sending unit that tells the high idle and GP controller when to turn on and for how long, not sure where but that is where i would start, think someone mentioned its next to the thermostat housing.

 

short answer:
test the GP's with at least the test light method(explained in the sticky threads or the link below)and battery terminals for corrosion.

"I would remove the ground wire (usually under one of the mounting bolts) and make sure it is getting a good connection by cleaning the connector and bolt."-Dave Sponaugle post #7 in thread linked below in long answer;






long answer:

check out all the tests i ran on mine when i first got the truck.lots of tests to inspect the whole GP system.
turned out to just be poor battery cables and some burnt out GP's.but a whole system check was easy using my haynes book.i list all kinds of 'em and more here.
sorry its kinda long winded thread,but lots of good stuff to learn:
https://www.ford-trucks.com/forums/8...old-start.html

the whole things a pretty good read,as i was a complete diesel novice going through it.but if you dont have the time,skim over everything,and read posts #13/29/30/31/33/34.

this site cant be beat.but if your interested,i really like the haynes book.its like 10 bucks and the # is 10330
its a nice basic diesel book i think and really helped me along with this site.it covers a few diesels.

as you notice there,though i was new to diesel,some of the things i was going through wasn't just for the GP system problem,but being a low mile rig(with age/rust/corrosion) i was going for preventative maintenance/upgrades too all at the same time.
since yours is like mine; basically a NOS (new old stock) rig.you may want to follow some of the other things i did there like new battery cables/fuel lines and im telling ya,the electric fuel pump conversion was one of,if not my favorite mod to date for the IDI.
good luck!

 

okay, can you guys tell me where the control module is and where the relay is? and what ground wire? the one from a relay?

 

look on the passenger side valve cover for this
there is a wire that runs to the front bolt that is a ground.some (including me) ran another ground wire right to the battery ground.

 

thanks I'll have to check this out

 

actually its behind the air cleaner on the n/a.
you'll see it covered up with a black plastic cap.

 

ok so ill remove the intake and airfilter housing and this will be behind it?

 

yeah.slightly to the drivers side a bit.you cant miss it.

 

93 year info.......other than some fuses mentioned the 7.3 system 87-94 is basically the same.

GLOW PLUG CONTROL
HOW THE CIRCUIT WORKS
The Glow Plug Control circuit applies power to the Glow Plugs, which heat the combustion chambers so that the diesel engine can be started.

Glow Plug Controller
The solid-state Glow Plug Controller, attached to the top of the engine block, controls the Glow Plug pre-glow and after-glow time. It also controls the circuit’s operation by sensing engine temperature, Glow Plug voltage and after-glow voltage from the start/run circuit.

When the Ignition Switch is turned to START or RUN, voltage from Maxi-fuse K is applied through the Glow Plug Controller to the Wait-To-Start Indicator Lamp.
The Glow Plugs heat up in zero to fifteen seconds, depending on engine coolant temperature. After the Glow Plugs heat up, the controller cycling switch opens and turns the Wait-To-Start Indicator Lamp off. The Glow Plugs are now warm enough for the engine to be started.

At the same time the Ignition Switch is turned to RUN, voltage from Maxi-fuse K is applied to the after-glow timer (located inside the Glow Plug Controller). The after-glow timer cycles the Glow Plugs for up to two minutes, depending on engine temperature. The after-glow timer then opens. The Wait-To-Start Indicator Lamp will not light during the after-glow period.
If the Ignition Switch is turned OFF, it can be turned to ON immediately, and the Glow Plug heating cycle will start again.

Diesel Start/Run
The diesel engine uses two batteries to provide extra power for starting and Glow Plug heating. Power is applied from the batteries, through heavy gauge wires, to the Starter Solenoid (located in the Starter Motor assembly). When the Wait-To-Start Indicator goes out, the Ignition Switch can be turned to START.

With the Ignition Switch in START or RUN, voltage is supplied to the Fuel Heater, Fuel Shutoff Solenoid, and the Engine Temperature Switch through Maxi-fuses K and U.
The Fuel Heater is in the Fuel Filter/Separator. It heats the diesel fuel, melting any wax that might clog the filter. The heater has an internal thermostat to turn it on as needed at 32*F.

The Fuel Shutoff Solenoid controls the flow of fuel into the injection pump. With the Ignition Switch in START or RUN, the Solenoid is energized, and fuel is allowed to flow into the injection pump. When the Ignition Switch is turned off, the solenoid is deenergized, fuel flow stops, and the engine stops running.

The Engine Temperature Switch provides voltage to the Cold Timing Advance Solenoid and the Cold Idle Solenoid. When the engine temperature is below 112°F (44°C), the Engine Temperature Switch is closed. When the Ignition Switch is turned to START or RUN, the solenoids are energized, advancing injection pump timing and engine idle, allowing the engine to run more smoothly when cold. When the engine temperature reaches 112°F (44°C), the Engine Temperature Switch opens. This deenergizes the solenoids, returning the timing and idle to normal.

 

hey guys I have an update, due to my headlight issue I didnt tackle cleaning the contacts of the controller being the air intake, but I wanted to get an opinion for this, sometimes when I go to start the truck the Wait to start light will come on and sometimes it wont come on at all, and its not the square on the dash where it lights up, because when I crank the engine to start it the other lights show while cranking but the WTS light does not, I'm not sure what this is but I'm pretty sure it has to do with the controller thing pictured above

 

Okay I have my intake off and can see this but still don't know what it is I'm looking at.. is it the controller or relay the bolts that are holding on all these wires look corroded/dirty I cleaned up my battery terminals, now would like to clean whatever is in this picture aswell the other thing that goes hand in hand with it basically I would like to clean the controller and relayy but don't know where they are I found this but where would the other be, to the left of this thing is a black thing with a wire going to the top of it, is that the controller? also when I opened up my airfilter there was like a light coating of oil on the soupbowl and on the metal grate where the filter housing sits? is this normal?? please respond guys thanks for all help so far with my new truck

 

bump anybody there?

 

This is the wiring diagram for your era of glow plug system (actually thats also most of the engine harness right there):



What is shown in the picture that Rupe posted earlier is the glow plug controller. The controller has a built in relay on it so that is the complete controller assembly.

The light coating of oil is normal. Diesels have a system similar to a PCV system on a gasser, and small amounts of oil vapor ingested by the intake is a simple fact of life. Nothing to worry about unless you start seeing large amounts of oil consumption.