White smoke and missing at altitude.

[dimspark]

Hey legends.
My 1HZ NA 78 series is playing up in mountains, about 1400m.
Runs sweet at sea level, but twice now up at altitude it feels like it's missing and blows white smoke under load.
Bring it back down lower and it's back to running fine.
Advice much appreciated, cheers.

 

[JDM Journeys]

Do you have a High altitude compensator on the top of the pump? I live at 1100m and frequent the (even higher) mountains. My early 1hz didn't have an HAC so I retrofitted one from a later 1hz. It didn't make a huge difference, but it helped a bit. I get no smoke at all unless I overwhelm how much air the engine can gulp at a given RPM (foot flat on the floor) but then I get black smoke.

Beyond HAC, assuming everything else is functioning properly, I almost always assume that there is some air getting into the system unless you've renewed the fuel system recently. White smoke and missing under load (usually) points this way. A clear (temporary) line between the filter and the pump will confirm or refute this possibility.) When were your injectors/pump renewed/replaced last?

You could advance the timing a bit to compensate, but honestly, unless you live at altitude, I wouldn't touch it if it runs perfectly where you spend most of your time. It is a slippery slope once you start messing with timing (At the very least, ensure your air filter is new or at least clear).

Someone who actually knows things will likely soon chime in and give you actionable intelligence...

 

[Gun Runner 5]

@JDM Journeys …. “Someone who actually knows things will likely soon chime in and give you actionable intelligence...”
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I was going to post but your criteria leaves me out.

 

[HDJ79R]

Hey legends.
My 1HZ NA 78 series is playing up in mountains, about 1400m.
Runs sweet at sea level, but twice now up at altitude it feels like it's missing and blows white smoke under load.
Bring it back down lower and it's back to running fine.
Advice much appreciated, cheers.

As a trained diesel plant mechanic of 35 years, what we were taught that has always held me in good stead is: white smoke = unburnt fuel, sometimes brought on by retarded timing, and could be related to the internal lift pump's ability to draw fuel without cavitating... Bearing in mind, the timing advance on those pumps is partly controlled by internal fuel pressure generated by the lift pump, which pressurizes the low side / inlet of the high pressure section. In short- low internal pressure will retard the timing curve. A simple test i have sometimes done on those engine is- with no load on (ie: when stationary / not even moving), is to slowly raise the rpm and listen if the engine misfires.

Make sure the fuel filters are clean before drawing any conclusion. Also, if when you take the fuel cap off, if you hear gurgling, the fuel tank breather vent is (at least) partially blocked. A lot of people assume the vent is in only in the cap, but recently when my 400,000 km HDJ79 showed this symptom, i went looking for a secondary vent, which i found, replaced and now it's stopped gurgling. Must do everything to minimize any vacuum at lift pump inlet as it prematurely causes pump failure.