1HZ sputter when hot under load, Im Stumped

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Aug 20, 2013
I have a 1hz naturally aspirated diesel in an 80 series. it has a C20 injection pump manufactured in 2007 I believe...

The Problem:
When the Motor is hot and under load, (im pushing the throttle down) the engine sputters/ stumbles white puffs of smoke come out the tail pipe, loss of power. When I let up on the throttle it runs fine no smoke, no sputtering idles great. When the engine is cold no issues only when it is hot and im putting it under load does it have a sputtering problem.

What I have ruled out so far:
Not an Air leak: I have run clear plastic tubing on all lines going in and out of the pump no bubbles. I will be monitoring the tubes when the vehicle is stumbling ect... ect... no bubbles anywhere.

Not a plugged fuel filter: I have dual tanks and separate filters on each tank replaced one of them, sputtering occurs on both tanks no difference from one to another.

Not Injectors: I just recently had the injectors rebuilt by industrial injection.

Not a head gasket: this was recently replaced and the coolant looks clean, no oil sheen, no brown coolant.

Timing. Maybe? I recently adjusted the timing to the middle of the range 0.85 - 0.91mm, granted im using a crap gauge but I checked it dozens of times to make sure it is smack in the middle of the range.

Could this be a timing issue?
Could this be a bad governer spring?
Could this be a bad delivery Valve?,

I'm assuming it has to be something in the injection pump????...........

Anyone had this problem before? If any super hero's out there could point me in the right direction I would greatly appreciate it.

Thank you.
You could be right. I did a buch of digging on pump timing this is what I came up with.

Toyota HZ Landcruiser 75/80 Series 1.03-1.09mm @ TDC
Toyota HZ Landcruiser 100 Series 0.85-0.91mm @ TDC
Toyota HZ Landcruiser 100 Series ACSD 0.65-0.71mm ACSD, 8mm spacer

As you can see there is a broad range depending on the pump?

So I sent an email to dencodiesel inquiring on the timing. They responded with this.

"Looking at the exploded view of your injector pump it does not have a cold start device fitted so the injection timing will be 0.85-0.91mm @ TDC"

So that's where I set it. I believe the motor came out of an hzj79 mine truck, date stamp on the valve cover was 2007.
OK, i had 80 series timing numbers in my head.

So my first thought from reading your problem was air in the fuel system.
Air bubbles muck up the injection timing momentarily, and you aren't getting the right amount of fuel.

White puffs of smoke is unburnt fuel, suggesting either way too much fuel, or incorrect injection timing.

Sounds like you have doubts on the accuracy of your attempts at setting timing, if you're 100% certain you aren't getting air in the system, maybe it's time to pony up for a better timing gauge set up and verify your timing. Or tweak the timing without a gauge and see if you can eliminate it as the problem before buying another timing tool.
A small change in pump orientation makes a significant change to timing. 1-2mm rotation can take you from in the ball park, to out of the parking lot.

One thing you don't mention is air filter. is it clean? And no obstructions in the air intake?
Timing it is!

I turned my injection pump clockwise, I don't recall if that advances it or retards the injection timing.
any way took it for a spin. Off the bat I noticed the engine starts right up no extra cranking. My EGTs were noticeably lower maby by 100 degrees and toped out sooner than before under load. no smoke, no sputtering, yippieee............

This picture is where it is set at now, before ,the pump line (on the right of the picture) was below the line on the left. I know this is not scientific at all but frankly, I'm 90% sure I set the timing to .89mm.

Im tempted to leave the timing right where it is because I don't know where it is supposed to be.

what are the symptoms or problems associated with turning my pump too far clockwise?
until I can purchase a proper timing tool it would be nice to know what to look for so I don't cause any damage to the motor.

mudgudgeon Your the Man!

Thanks for the Help!

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