Adjusting 1HZ for altitude (1 Viewer)

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Hi Guys, I've been looking through the FAQ'a and other posts about 1HZ underpower issues but can't find an answer to my question, hoping you got some input or can share a link from this forum.
I recently bought a '91 HZJ77 with a non-turbo 1HZ and since I live at 8500' (~2600m) I need to adjust, or lean out the pump just a bit otherwise I'm blowing a TON of smoke pretty much everywhere I drive. This is an issue on short or long hill climbs. Since EGT are a concern, I will be ordering a EGT gauge and probe and hopefully can do some minor adjustments to the pump. I am not really concerned about flying through any hills, the cars shifts fine and drives great but I don't want to push my luck. I've included a pic of the pump. Do you you have any experience with leaning out the fuel on these pumps? Thanks in advance.

1hz fuel pump.jpg
 

mudgudgeon

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Adjusting fuel is very basic on these pumps. There's just one fuel screw, you'll have to remove the anti tamper collar. Then after adjusting the main screw, you'll need to tweak the idle speed

Cutting fuel will probably make it sluggish.

Maybe fit the EGT gauge and see what temps you are getting
 
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@mudgudgeon Side question: What is the best way to remove the anti tamper collar, was worried if i screw it out all the way to do it outside the truck it will not go back without taking the pump apart, can you confirm that is not the case?
 

mudgudgeon

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You can fully remove the fuel screw and reinstall without dissambly.

The collar is on the lock nut, not the screw. If you can crack the nut loose without completely mangling the collar, you can leave the screw in, and remove the nut
 
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I prefer naturally aspirated engines generally, they are simpler, and have potential for longer lifespans than equivalent turbo engines. Often a turbo diesel is used unnecessarily, when an N/A would do, although it does have applications.

Having said all that, I think a turbo diesel engine is definitely the way to go here in your case, rather than fighting with an NA at altitude.

Good luck.
 

FJBen

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Turbo!
I grew up at 8100’ elevation and any NA diesel was basically a turd.
A typical NA diesel loses 3~4% power for every 1000' in elevation. Rough math puts that ~20~25% of stock horsepower, which on a 135hp engine puts you closer to 100hp at the crank. Add in mountains/grades and a heavy 4 door cruiser and it's going to feel slower than normal.

You absolutely can turn the IP down. It's possible it was turned up before thus making it smoke more like a freight train up there. How does it run in Denver or lower altitude? EGT gauge for sure. When I lived closer to 4000' elevation, I could still make my little NA diesel smoke.

Get that gauge and see what you are running temp wise, then adjust from there if you need to.
 
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Turbo!
I grew up at 8100’ elevation and any NA diesel was basically a turd.
A typical NA diesel loses 3~4% power for every 1000' in elevation. Rough math puts that ~20~25% of stock horsepower, which on a 135hp engine puts you closer to 100hp at the crank. Add in mountains/grades and a heavy 4 door cruiser and it's going to feel slower than normal.

You absolutely can turn the IP down. It's possible it was turned up before thus making it smoke more like a freight train up there. How does it run in Denver or lower altitude? EGT gauge for sure. When I lived closer to 4000' elevation, I could still make my little NA diesel smoke.

Get that gauge and see what you are running temp wise, then adjust from there if you need to.
Awesome response Ben, thank you. I just ordered the temp gauge this morning and will see where I'm at driving below in denver vs. going up the hill to Conifer. It runs a LOT better down below which is saying much since "below" is at 5200'. I just need to figure out which screw is the adjustment screw.
 

FJBen

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Awesome response Ben, thank you. I just ordered the temp gauge this morning and will see where I'm at driving below in denver vs. going up the hill to Conifer. It runs a LOT better down below which is saying much since "below" is at 5200'. I just need to figure out which screw is the adjustment screw.



That run from Denver to Conifer eats a lot of HP. My old FJ55 2F on 35's was 35mph tops 🤣 on that. Gives you more time to enjoy the mountains.

Should be the screw like this on the back. Just go in like 1/4" turns and see how it reacts. The more it's lowered, the less fuel and less power you are going to get. Get the gauge on and go from there...and plan for a turbo :beer:

20180217_102548-jpg.1634915
 
Joined
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That run from Denver to Conifer eats a lot of HP. My old FJ55 2F on 35's was 35mph tops 🤣 on that. Gives you more time to enjoy the mountains.

Should be the screw like this on the back. Just go in like 1/4" turns and see how it reacts. The more it's lowered, the less fuel and less power you are going to get. Get the gauge on and go from there...and plan for a turbo :beer:

20180217_102548-jpg.1634915


That run from Denver to Conifer eats a lot of HP. My old FJ55 2F on 35's was 35mph tops 🤣 on that. Gives you more time to enjoy the mountains.

Should be the screw like this on the back. Just go in like 1/4" turns and see how it reacts. The more it's lowered, the less fuel and less power you are going to get. Get the gauge on and go from there...and plan for a turbo :beer:

20180217_102548-jpg.1634915
Big Thanks FJBen.

-David
 
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:popcorn:One of the origional application for turbo's , way back when, was altitude compensation for diesels:popcorn::popcorn: way before the performance application. If this area is where you are going to be setteling for a while, then an HD / HDFTmay be appearing in the old crystal ball.
G
 
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1573002598360.png

Perhaps a good start would be to get a pump shop to h fit a HAC and recalibrate. We run around Lesotho, a small neighbouring country at almost 3000m, with these, and although the power is definately down, not a lot of black smoke.
 
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View attachment 2126318
Perhaps a good start would be to get a pump shop to h fit a HAC and recalibrate. We run around Lesotho, a small neighbouring country at almost 3000m, with these, and although the power is definately down, not a lot of black smoke.
Good info sir! I'll do some research to see if I can source one. There was a member on here selling them while back, I'll need to track him down , otherwise my other options were super expensive from overseas for around 1k usd
 

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