Adding HAC to B engine that's never had it, questions. (1 Viewer)

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Rusto

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Ah, it's good to be back on the Diesel Tech forum. It took me waaaay too long to get my 75 BJ up and running after cleaning out the fuel system completely. But the fuel system is clean. The inline fuel filter I added for more visibility is showing wonderfully clear and the 40 is running smooth. I changed out the diaphragm just to be sure, even though it was in pretty good shape.

With that being said, I'm driving around at 6,500 feet at a minimum with excursions up above 10,000 feet on the weekends and it's puffing out a little bit of black smoke on the reg.

The engine never had an HAC and I have one ready to put on along with the bracket, but I don't know what else is needed.

The Toyota Engine Repair Manual isn't much help as it just shows the HAC, but nothing hooked up to it. Obviously, it has to connect to vacuum, but where?

Can someone help me understand what connects to the HAC and where?

Thanks
 
The HAC on my HZJ105 had no vacuum lines hooked up to it.
It works with a set of spring loaded bellows. As altitude increases, atmospheric pressure drops, and the bellows move and change the fueling
 
Thanks for the reply @mudgudgeon . It's hard for me to tell exactly how it's hooked up on the 40 as the pictures are limited in the Toyota Engine Repair Manual.
Here's what I can see in the manual on page FU-30.
1658243646828.png

and on page FU-35
1658243745272.png


The later pics for 11B, 12B and 13-BT show a connecting link, like you describe.

I thought I saw a picture of a vacuum home coming out of the nipple on the HAC, but now I can't find it.

Would love it if someone had a picture of an HAC hooked up correctly on a B Engine.
 
I have an Isuzu 4BD2 engine in my 60, but it has a HAC. On mine, the hose attached runs into the cab for a clean and dry air source. Don't run it to the air cleaner.
 
@mudgudgeon - good idea. Attached are two pics, and after looking at the components I have, and the pictures again, it's starting to make a little more sense.
The second diagram above, from FU35 appears to show the black, plunger looking part of the HAC butting up against the flat metal piece that connects to a cable that then connects to... something.
At this point, I assume that when mounted and the air pressure changes (or maybe vacuum?) the HAC lengthens or shortens the "plunger" and that moves the metal piece that attaches to a cable. The cable then alters something.....?

IMG_7317.jpg


IMG_7318.jpg
 
Hmmmm, not sure.

The HZ use a rotary injection pump, and the HACS is integrated into the pump.

That one looks like it acts on the throttle arm to increase idle position?
 
The vacuum line is vented to the atmosphere. It's purpose is to go to an area that's unlikely to get water and dirt in it. There's a diaphragm inside the HAC that is responsive to changes in atmospheric pressure and changes the length of the full-stop position. Think of it as a variable-length fuel screw.
 
This is 2H HAC but same like for B engine too.

If you need HAC parts i will help you.
 
@himhj60 - wow that video was great! Thanks for sharing. Starting to understand this more

Sorry for the long bouts between replies. One of my best friends fast moving cancer started moving even faster shortly after this post and we lost him a couple of months later. Crappy situation and he passed on at 52. Hug your loved ones and make peace with your enemies (or better yet, don’t have any to begin with)

Time passes, the world slowly returns to the new normal. Ive sold my FJ60 and now I’m back and focused on this again. I’m digging in and hoping to get this sorted before SAS7

@himhj60 - I’ll take another look at what I have and see what may be needed.

Nice to see one working correctly at 14,000 feet. I probably won’t ever be higher that 12,500 or 13,000 for the foreseeable future

More to come. And soon I hope
 
I think I’m going to have to take off the injection pump to really get a good look at this and get the HAC put on right.

The bracket seems to match what’s in the picture, but it doesn’t want to fit where it should. And even it fit like a glove, it seems next to impossible to actually get to.

This may be a bigger job that I’m up for at the moment.
 

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