1HZ Diesel pump adjustment for temporary high altitude

[EsbenDenmark]

I hope you guys can help and give some advice.
We are on our way to central Asia in our 75 series. It runs GREAT, but I expect to have issues on the high mountain passes.
We already had issues in Armenia above 2500 meter (8000 feet) and really ran like s*** at above 3000 meter (1000 feet)
The engine was puffing WHITE smoke and could bare get above idle.... Not black smoke as expected!!!!!!
It is a non turbo 1HZ engine. I have replaced the original exhaust with a side muffler from Tourfactory in Germany. (See attached picture)
Also installed a Safari Snorkel with a centrifugal prefilter. (see picture)
Otherwise the engine is stock!

So when we get there I want to play around with adjusting the fuel mixture and hopefully be able to get the engine to run just a tiny bit better.
so a few questions

1. Any trick to loosen the little adjustment screw? Looks like it has a locking nut? I do not want to break anything while on the road!!

2. To LOWER the amount of fuel. Do I unsrew or tighten the little screw?

3. How much? I am guessing I should only turn maybe 1/4 or 1/8 of a turn and then see how it runs. But what is your experience???

4. Any great idea on how to mark the adjustment screw so I am sure to get it back to the precise setting again?

 

[Eurasiaoverland]

You have already posted your problems on this thread, which went cold: 1HZ high altitude smoking and sputtering - https://forum.ih8mud.com/threads/1hz-high-altitude-smoking-and-sputtering.1346197/

As I said in that thread, your engine has a fuel supply problem which manifests at high altitude. White/blue smoke and sputtering/cutting out are not symptoms of high altitude. Did you see other vehicles having this issue?

Air is the limiting factor on a diesel engine in standard tune. There is no adjustment for air density on a 1HZ (no air-flow meter etc.) so when air becomes scarcer, the same amount of diesel goes in and you get incomplete combustion leading to black smoke. Look at the trucks labouring up the passes around you.

Blue smoke or white smoke indicate completely unburned fuel, which together with your engine cutting out, indicate there is a fuel supply problem (i.e. erratic fuel supply). The issue is most likely air getting into the injection pump, or some other problem with the pump.

You talk about adjusting the pump temporarily. What you are referring to is the maximum injection screw. It is an adjustment made on the bench by a technician who knows how to set up these pumps. Given that you think it will adjust fuel mixture (which implies you do not know the fundamentals of a diesel engine and fuel system), I can only say to leave it alone. The maximum injection screw adjusts the maximum fuel injection volume, i.e. when you have the pedal to the floor. It will not do anything for the injected volume when you are off the maximum. So unless you use the accelerator pedal as an on/off switch, it will not help you.

Try running a clear fuel hose from your filter to your pump and watching for bubbles. You can also try removing the air filter to intake manifold hose (i.e. running unfiltered air for a minute) to rule out an air supply problem.

 

[Eurasiaoverland]

One more thought on the symptoms - when exactly did they start? Were you getting black smoke, then turning to white/blue smoke and lumpy running as the altitude increased? Or did the white/blue smoke and bad running suddenly start?

 

[EsbenDenmark]

Thank you for your response.

What is interesting is that I never have black smoke.
It goes directly from running fine (of course a bit less power in elevation) to white smoke.
At least if there is any black smoke it is VERY VERY little.
So Yes a very sudden thing and was gone just as sudden going back down.

As far as I can see there is an high altitude compensator on this model fuel pump..
So I had expected it so run better and yes I was expecting low power and tons of black smoke.

Just not what happened.


If I was at home in Denmark would for sure visit the local diesel Guru but I do not have this option while on the road. Do not really trust the mechanics around here.
Right now I am in countries with no high altitude so this will be sort of a long term project.
Will get back to Georgia and hopefully up in elevation in late August.

About the clear tubing.
I will try this again when I get a chance to buy a bit of clear tube.
Actually it would be great with a small clear hard tube always installed.

I actually had a similar problem when I got the truck.
The fuel filter bracket/primer pump was leaking and I had air being sucked in and I could see clearly bubbles in a clear hose I had installed from the filter to the fuel pump.
The symptoms was small losses of power when driving fast on the Freeway.
So the primer pump is brand new and after there were no bubbles and not symptoms like that.
All fuel hoses are new.

And yes. I do need to learn more about diesel engines as this is my first diesel car..

 

[Eurasiaoverland]

From your previously posted video, it looks like you were driving up a steep off-road ascent (Gegham Mountains in Armenia?) with a very heavy vehicle. If I recall, that track goes up to about 3300 m which, for my Hilux (powered by an engine which is basically a 4 cylinder 1HZ) was below the altitude where it would easily make black smoke. For me, I found that started at about 3500-4000 m and I never had any symptoms like yours, even well above 5000 m.

Aside from the drop in air pressure, what was different from normal when the symptoms started? Was it colder, steeper inclination, rougher terrain, heavier load on the engine etc? How is the engine on a cold (sub zero) start (at any altitude)? Was it a one off? Could it have been some bad fuel at the time?

Maybe it's time to start working through the fuel system. Check the tank for rust/sediment/microbial growth. Check fuel lines. there can be tiny splits which only open when things expand or contract. Do you have a dual fuel filter? That could be restrictive. When were the injectors last serviced?

If you don't find anything obvious, I would look at getting the pump and injectors serviced at a decent diesel specialist, I would expect there is at least one in Tbilisi as there are lots of Land Cruisers and imported cars there. I would not wait until Central Asia. If you get those symptoms again you'll have a miserable time getting close to the Pamir Highway and miss out on a great experience.

 

[EsbenDenmark]

Yes. I will definitely go through the fuel system.

I am sure the tank is fine. I cleaned it before we left Denmark. But I will check.

Check all connections on fuel hoses.

Install clear tube to make sure there is no bubbles.

I do have additional prefilter. Just changed both prefilter and normal filter.



Unfortunately I do not think I will hit any really high altitude roads in Georgia or on the way there.

Oh and yes.. who knows.. it might be bad fuel and it will never happen again.