Hello all,

I'm new! Got a diesel about 2 weeks. 1993 F-250 7.3L non-PS, 263,000 miles. Was cranking and running fine until 4 days ago. Overnight it started bellowing white smoke (smells like raw diesel fuel) with a very labored idle at start-up, continues to smoke the white smoke after warming up, just not as bad and the idle smoothes out somewhat. When going thru the gears it feels like it really starts to miss around 2200 to 2500 RPMs in 1st & 2<SUP>nd</SUP> but not after that. The only things I have done to the truck since I got it is pressure wash the engine, change the air filter, fix the A/C. I have checked the GPs all show .04 to .05 ohms and I have voltage on the GP harness while the wait to start light is on. I have read some of the postings and it seems to be a mixed bag of what could cause this injectors, IP, timing, water in the fuel, bad riser pump it seems like a scavenger hunt for the actual trouble. Does anyone have a better place to start trouble shooting this trouble than what I have found so far? Any help would be much appreciated. If this were a gas engine I would say it’s running very rich!<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
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Thanks,<o></o>
Dwayne

 

Is the fast idle solenoid and timing advance working on the IP......... are you setting the FI and with key on by pushing the fuel pedal once just before start. Is there power to all 3 electrical locations on the IP (cold engine).

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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.

 

When you pressure washed the engine was the ip still hot? I remember reading on here not to get the ip wet wet when it is hot or it will mess it up real bad. Did this problem start before or after the cleaning?

 

Where the problem with getting the IP wet comes from is temperature change.

Hot IP and cold water = big problem

150 degree IP and 150 degree water = no problem

The IP has very close tolerances and clearances.
The sudden temperature chance causes expansion and contraction of the metal to make a close clearance into no clearance.
Metal to metal contact in an IP ends in disaster.

As for the engine problems.
My guess is when you pressure washed the engine, you disturbed the return lines enough that air intrusion is what is causing the rough idle at start up.

Depending on how bad the return lines are leaking air, the white smoke may be from air.

Have you used any fuel treatment in your fuel?
A good strong dose of Diesel Kleen or some other fuel system cleaner may fix your problem.
Are the injectors painted grey?

You are due for new injectors if those are originals.

And if the engine was hot and you washed it with cold water, the IP may be on it's last legs.

 

Thanks for clearing that up for me Dave. I just remembered it was bad and never to do it.

 

got a 91 7.3L diesel started running rough on start up. Now won't fire... Possible cause??

 

Was running fine then just started taking long time to fire up. Would it be the fuel or the glow plugs?