I just got my first diesel its a 91 f-350 w/7.3 idi I dont think it has problem starting my concern is my son is going to be using this truck as daily driver to our job sites. and I want to know that he doing things right.... He turns the key to the on position and waits for the dash indicator to go out, then he cranks it over i wanna say for like a good 3-4 seconds and it doesnt fire right up on the first cranking so he pauses lets off the key then hits it again and this time she fires right up no more than 2 seconds of cranking.. now in my sons defense the man we bought did this exact procedure too. so maybe my sons thinking this is the way to do it. My question is should it not fire right up on the first cranking session (we havent tried it to see if it would by cranking it longer) or is this a common practice to crank it twice. seems to me that by stopping and then recranking your causing extra wear and tear on the starter? Im just learning these diesels and hesitant to tell my son different if I dont know what im talking about.. Just wanna be safe than sorry thanks guys

 

Make sure he waits untill the (WTS) Wait to start light goes out......

How ...The Solid State Circuit Works ........

This is 93 info, but other than the "maxi fuse" operation is same.


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.

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 denergizes the solenoids, returning the timing and idle to normal.

To start turn key on press fuel pedal to the floor, then if above 30*F hold at 1/2 throttle, if below 30*F hold at 3/4-full throttle start engine. Once started release the fuel pedal to the fast idle setting or feather pedal to keep running.

 

Rule of thumb,
Crank the starter for 20 seconds max.
That must be followed by 2 minutes cool down time minimum before cranking again.

For the first start of the day, the wait to start light should be on for about 10 seconds.
Wait to start light on for a shorter time usually indicates a burnt out glow plug.

When you say he lets off the key, is he returning the key to the off position?
If so, the glow plugs will heat again when he turns it back to on.

 

I am wondering if the controler is starting to give problems.

Another problem might be this. Is the fuel return lines (located between injectors) painted "gray". If they are they need to be replaced as they are letting air into the fuel system letting the fuel drain back towards the fuel tank giving a - no start - due to lack of fuel.

 

He only just releases the key from the cranking position you know so the starter is not cranking then he hits the key to crank the engine and she fires right up in about 3 revolutions. weird im gonna try tomorrow and see if on the initial crank up if she wont fire in a reasonable amount of time. No i wont over crank it and get the starter hot. I just kinda think it should start the first time around. I do love this truck though. thanks dave

 

Kinda odd that it takes a second try if he's not returning the key to the off position. If he is just releasing it and letting it spring back on it's own then the glow plugs are not reactivating. I'd guess at air intrusion in the lines as has been suggested.

 

If its air intruision wouldn't that effect the overall performance after starting as well? And how does a fella check for this air intrusion. Are you suggesting items like a loose fitting or fuel filter? thanks

 

Generally the air is worked out by the starting process, so it doesn't usually effect overall performance. Once the air is purged from the system during startup she should run fine. There are a few places to check but the injector return lines are usually #1 on the list. I'd start there.

 

It will when it gets bad. In the beginning it is a slow start which keeps getting longer.
There isn't really any test other than taking the hose from the filter to IP off before trying to start. See if when you first try to start you get fuel immediately or air.
What happens is air will go in thru small hairline cracks in the hose not large enough to let fuel out. This has been a common problem for several years now.

 

Check out this page for clear hose test for air intrussion....... lots of good reading here...

Ford diesel 6.9 7.3 IDI

 

Wow that is informative I printed that baby already for my diesel file thanks!!

 

turn key on and listen for the glow plug controller to start cycling and wait until it quits clicking if it is 50 degrees or coooler turn the key off and back on and let the glow plugs cycle again then depress and release the throttle to set the fast idle solenoid then engage the starter
if its cold outside try cycling the glow plugs three or even four times before trying to start the engine

 

mine was doing this same exact thing. then i was fooling around on the engine and bumped one of the return lines and it went from on a scale of 1-10 maybe a 2 to a full blown 10 where it wouldnt start at all and took me a good 1/2 hour. turns out when i bumped the return line it cracked the plastic T cap ever so slightly and it wouldnt build pressure in the injector lines.

i got a replacement kit and put in some Beru glowplugs (didnt need em but i got em from autozone when they were on clearence cheap and for my own personal piece of mind). now it starts right up after the WTS light goes on.

moral of the story, DONT BUMP THOSE RETURN LINES, lol.

 

Quick question on replacing those return lines and the glow plugs. Does the system purge itself of the air, or do you have to do this yourself in some way when replacing the lines? Or is there no concern with air when replacing these things?

 

it'll purge itself to a point. i changed my fuel filter at the same time so i filled it up and that helped getting it started.

if it doesnt start right away u can crack (slightly) one injector line until u see a little fuel dribble out.