Ok.. I posted this a few days ago but I did some testing and figured I'd get a fresh start. Heres the problem.



When I start my truck cold it smokes like a barn fire. There is
so much smoke I can't see the ground looking out the window. The
smoke is white and doesn't have much of a smell.



The truck starts really easy but I checked the glowplugs anyways and
they all seem to be fine. Once the truck is warmed up after a few
mins the smoke goes away and its fine again till it cools down.



Theres no PCM therefore no way to check for codes.



'94 6.5 turbo in a 88 3/4ton

How many miles on your injectors? How many mm's advanced are you running the pump?

Injectors are originals.. about 100k miles. Timing is stock as far as I know... never checked it.

Injectors are expensive but only good for up to 100,000. Timing chains only last 100,000 also,before they have excessive play, more than 1." is excessive.


Fuel shops can test injectors for atomization and opening pressure.


Loosening the IP and moving it 1mm driverside advances it and will take up chain slack. Edited by: quantum mechanic

Engine off, timing chain is locked into positon by valve spring pressure on rocker arms on push rods on lifters on cam lobes, preventing rotational movement of camshaft, driven sprocket, IP drive gear,and driven IP gear.


Moving Inj Pump in either direction cannot take up any slack from worn timing chain.


What QM is suggesting is to slightly advance IP timing to compensate for mechanical slack caused by worn timing chain.


Timing chain and sprockets wear allows camshaft and Inj Pump to slowly retard with respect to crankshaft - advancing the IP can help some.


If your engine has 100kmi or more, it's time for new chain and both sprockets.


Which will restore lost power, all else being functional.Edited by: gmctd

Now - Diesel fuel, as white smoke, is unignited fuel, where temperature was never high enough for ignition.


Odor is raw Diesel fuel.


Could indicate insufficient glow time - 60G'S require greatly extended on-time to match 11G heat.


Could also indicate HPCA not working - '94 engine would be PCM controlled, so no HPCA switch.


'88 Diesel truck should have had correct wiring - orange, green, iirc - with switch in passenger-side head, at rear, above exh port.


Should also have had glow controller Engine Coolant switch in t-stat crossover - 2 wires, yellow and black.


'94 engine would be PCM controlled glow, so sensor in t-stat crossover would be Engine Coolant Sensor, a temperature-variable resistor - not workable on your truck, at all.


Water vapor, as white smoke, would have odor of Diesel exhaust.


And antifreeze, if used and a coolant leak exists.

The coolent temp gauge in the truck doesnt work.. I'll replace it but I think it started smoking before that.

That sensor, driver's-side head front, may well need to be replaced, but what you're after is the glow controller sensor, usually in the t-stat crossover, and the HPCA switch, usually in the passenger-side head above #8 exhaust port.


Those two control cold starting - are they installed and wired?

What is the HPCA switch? Does the glow plug controller have a
computer to moniter these two sensors? I read somewhere that
unplugging the glow plug controller sensor it would default the temp to
-40 and leave the plugs on super long. Would that work on my
truck? Anyway to test the HPCA switch like this too? Thanks

Housing Cold Pressure Advance switch enables a solenoid valve in the pump, such that internal fuel pressure is bypassed to the tank.


With housing pressure reduced, more advance is available for cold starting.


HPCA switch enables the solenoid when engine coolant temps are below ~85deg, or so.


Also kicks in the Fast Idle Solenoid, on the driver's-side of the Inj Pump.


Orange wire to one terminal of the HPCA switch


Should be a green wire from the other terminal of HPCA switch to the HPCA solenoid, then to the Fast Idle solenoid.


Should be another sensor on the t-stat crossover, over by the heater hose outlet, controls glow on-time.


On my '89, was two-wire unit with yellow and orange wires.


Orange is ignition +12volts, yellow wire to glow controller


'94 engine would have had sensors for PCM, which your truck does not have.


Sensors from '88 engine should have been transfered to '94 engine, and would match wiring on your truck - was this done?

88 was a gasoholic before I got my hands on it.. I let another guy do
the swap for me cause he owed me money.. The problem just started so Im
sure he had it done right... Probably took everything from the 94.. I
was told the 94 didn't come with a PCM of anykind..

Well, then - without knowing your location, white smoke could be normal starting in the great white North, where water vapor and white Diesel fuel vapor combine to fog, until engine and exhaust warms up past 100deg or so.


Winter climes, and all.


Still - check for sensors and wiring as noted above, along with completed connections.