I'm new to diesels, and I don't know what or how to check to find what is wrong. How do I know if it is the glow plugs, the gp relay, or the gp controller that is bad? The truck starts ok as long as I plug it in at night, but it starts a lot harder in the afternoon after sitting all day to get cold. I know the fuel heater must work, because if it is cold out the truck will not start unless I wait for the little "wait to start" light to turn off, even when plugged in. I'm interested in just putting a manual button for glow plugs, but I have not yet been able to get a diagram to know how to do it. Will going to the manual control stop the fuel heater? Will the wait to start light still work? Thanks

Dwayne

 

Go down the page to "bypass switch". Switch hook up is there. My WTS light does not work since I put in the button. Also check out www.members.shaw.ca/k2pilot/. Alot of good info there, but the switch diagram is the older style. You should be using motorcraft/beru gps. They are the best. I don't believe the manual control has anything to do with the fuel heater. Buy a Haynes manual for your truck. You will need it for general information, specs., and how to stuff. Check your coolant to see if additive has been used. Buy some test strips at a place like Napa, Ford, or International. Do a search, there is a load of info on gps and controllers and testing. I am also new to diesels, but there are alot of very experienced people here to help. Good luck with the truck.

 

IF you are new to diesels, I'd stay away from the manual switch. It sounds to me, like you have a GP (Glow Plug) issue. Maybe one, or more, bad GP's.

The light that you see, is the Wait To start light. It's telling you that the glow plugs are heating, wait till they're hot, (light goes out) before you crank the engine. Try that first.

Where are you located, and what types of temps are we talking about?

 

One more time.........this 93 operation other than fuses mentioned yours does th e same........

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.

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.

 

VEEEEERY good info. This should be FAQ'd somewhere

 

Awesome info...I wish I would have read this before I posted my own Glow Plug question. Sorry for the repeat.