1HD-FT /1HD-T pump

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B

benfun

Joined
Jun 19, 2016
Threads
3
Messages
9
Location
Finland
I'm going to swap 1hd-t to 1hd-ft Euro engine(remove the egr), and wondering which injection pump to use.
A lot more pipes on 1hd-ft pump, ( BACS. SICS ) .

Can I use the 1hd-ft pump and remove all vacuum pipes like BICS and SICS actuator.?
How much will i have to change the pump settings ?
 
Any yes, you can delete all the extra vacuum, throttle position and EGR stuff. My Euro spec engine runs great without it.
 
Rock40 said:
Any yes, you can delete all the extra vacuum, throttle position and EGR stuff. My Euro spec engine runs great without it.
Click to expand...

You mean that I can leave the BACS and SICS without any vacum line
without to adjust the pump because of this ?
 
Thread revival.

After heading up to the Sierras last weekend, I am looking at reconnecting my BACS and SICS systems. My 1HD-FT motor was from the OZ market, without EGR, and had the mechanical BACS diaphragm.

On my rig both the SICS and BACS were disconnected, with a cap on the SICS, and an open line on the BACS...not sure why.

Here is what I am planning:

  • SICS = Starting Injection Control System. This is the diaphragm on the engine side of the IP, and reduces fuel on startup. The SICS needs constant vacuum once the motor is running to ensure that max-fuel can be delivered. I will be running a vacuum line directly from the vacuum pump. If I understand this part of the system, I was never actually getting max-fuel, as it was disconnected and capped. I tested the diaphragm per the FSM, and it works correctly when hooked up to vacuum/engine running, moving the lever 3mm off of the rest/stop. Will see if the truck accelerates better tomorrow when getting onto the freeway.
  • BACS = Boost and Altitude Compensation Stopper. Controlled by a manual altitude diaphragm, 25709-17030. The diaphragm is connected to directly to the vacuum pump, and passes the vacuum to the BACS port on the IP. The diaphragm shuts off the vacuum when over 4000' in altitude, reducing the amount of fuel. At altitude the truck definitely was over-fueled and creating more soot than I would like, especially when cold. The only odd thing for me is that there has been no vacuum hooked up previously, so it should have been running lean? Will have to see.
Any thoughts/comments/wisdom from the 1HD-FT Mud collective? @orangefj45 @70sguy @Jan-78FJ40 @gifu @Rock40

Reconnecting both should enrich the fuel if I understand their function correctly.
 
Last edited:
Test #1 done with the SICS hooked up.

What a difference in the power from 2800 rpm to 3800, as the motor feels like it pulls stronger as the rpm increases, instead of falling. :steer:

Will drive another day like this before reconnecting the BACS.
 
Steve, do you have pics of either? I don't think my UK spec pump has either the BACS or the SICS. But it DOES have some sort of goofy throttle position sensor thing
 
Here is a good shot of the SICS actuator and diaphragm, in the 2nd picture below. This has a constant vacuum line from the vacuum pump (though from the factory there is a VSV to switch it on/off). I have it set to factory "no gap" when the motor is off, and it quickly moves to a 3mm gap once the vacuum pump pulls a vacuum.

full


Here is the FSM picture of what the BACS vs. no BACS port looks like. If there is no BACS, then there is a bolt and a rubber cap, and if has BACS, then there is a vacuum port. Mine has the port, and I am plumbing later today to the vacuum system and the mechanical atmospheric diaphragm.

full
 
OK, more success!

Today I installed and plumbed the BACS diaphragm, and added a VSV to control the SICS system. I found out that the vacuum pump held a vacuum even after the motor was shut off, thus defeating the purpose of SICS and need for the added VSV.

The pic below gives a good indication of how I have set this up. The vacuum from the vacuum pump is first is T'd at the blue VSV for the A/C Idle Up, then T'd to the red VSV for the SICS (triggered by IGN), with the final line going to the manual diaphragm for the BACS. It is actually a very simple setup.

full


While I was "in there" I decided to follow the FSM test for the Boost Compensator, and it failed. It is supposed to hold pressure, but it was not meeting spec...thus I needed to pull the aneroid and see if the diaphragm was torn.

First order of business was to get the cover off while the IP is in the truck...not simple with the 1HD-FT, as a standard 5mm allen key does not fit. Out came the grinder, and I have a custom SST now.

full


What I found was the two spring seats which on each side of the diaphragm had rust between them and the diaphragm, thus I cleaned them up with steel wool, and also cleaned the rust off of the diaphragm. This helped to get it back close to spec (though I will be adding a new diaphragm and seats to my next order from the UAE).

I do not think that my aneroid is stock, as the base had a factory cut to allow it to be re-inserted into the pump easily. Another item was that I had to remove the diaphragm from the pin before it would clear the pump and intake manifold. Anyone else with a 1HD-FT have the same pin or have an idea what this one may have come from?

full


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It was indexed to be just about the max fueling setting when on boost.

So, once everything was back together I went for a 10 mile drive to warm up the rig and be sure that everything was working correctly. The truck had more power, and enough that when I came up my hill (12% grade) in 2nd gear in the rain, the truck hit 20psi of boost, and for the first time did a four-wheel burn out. :hillbilly:

I figure that I can now start fooling with the fueling.
 
One more thing : Boost compensator spring is different in 1hd-t pump without Bacs /1hd-ft pump whith Bacs.
"Softer spring in pump without Bacs . Boost pressure moves Diaphragm more lightly without bacs (vacum) ??"

Bengt
 
CycloSteve said:
Thread revival.

After heading up to the Sierras last weekend, I am looking at reconnecting my BACS and SICS systems. My 1HD-FT motor was from the OZ market, without EGR, and had the mechanical BACS diaphragm.

On my rig both the SICS and BACS were disconnected, with a cap on the SICS, and an open line on the BACS...not sure why.

Here is what I am planning:

  • SICS = Starting Injection Control System. This is the diaphragm on the engine side of the IP, and reduces fuel on startup. The SICS needs constant vacuum once the motor is running to ensure that max-fuel can be delivered. I will be running a vacuum line directly from the vacuum pump. If I understand this part of the system, I was never actually getting max-fuel, as it was disconnected and capped. I tested the diaphragm per the FSM, and it works correctly when hooked up to vacuum/engine running, moving the lever 3mm off of the rest/stop. Will see if the truck accelerates better tomorrow when getting onto the freeway.
  • BACS = Boost and Altitude Compensation Stopper. Controlled by a manual altitude diaphragm, 25709-17030. The diaphragm is connected to directly to the vacuum pump, and passes the vacuum to the BACS port on the IP. The diaphragm shuts off the vacuum when over 4000' in altitude, reducing the amount of fuel. At altitude the truck definitely was over-fueled and creating more soot than I would like, especially when cold. The only odd thing for me is that there has been no vacuum hooked up previously, so it should have been running lean? Will have to see.
Any thoughts/comments/wisdom from the 1HD-FT Mud collective? @orangefj45 @70sguy @Jan-78FJ40 @gifu @Rock40

Reconnecting both should enrich the fuel if I understand their function correctly.
Click to expand...

Hi, up,
very interessant topic, I'm looking for informations about deleting all the BACS and SICS on my 1HD-FT with european spec, EGR has already been deleted, i've got a 3" exhaust and a top mount cooler,
If some of you have pictures of the pump with SICS/BACS deleted on his EGR version I would appreciate.
And also a picture with an australian version to compare.

When you says deleting BACS, it means unplug it from the injection pump (under the LDA)? and leat the hole free on the injection pump but plug the hole with a screw on the bacs side to avoid vaccum leak on the circuit?

Aslo when you said SICS limited max fuel about 3mm, does it mean that we can play on it's adjustment?

Thank's a lot, 1HD-FT friends ;-)
 
HJ61alex said:
When you says deleting BACS, it means unplug it from the injection pump (under the LDA)? and leat the hole free on the injection pump but plug the hole with a screw on the bacs side to avoid vaccum leak on the circuit?
Click to expand...
My BACS isn’t deleted, but I took apart the boost compensator yesterday and saw how it works.

The BACS port is below boost controller diaphragm, unless you are above 4000 ft the BACS system isn’t on, the controlling vsv is closed, and that chamber is more or less at ambient air pressure.

When the system is on, the vsv opens and pressure in that chamber drops or even become vacuum. Presumably that applies some downward pressure on the diaphragm, effectively sucking it down, and thus acts as if you had higher boost and increases fuel accordingly.

So if you plan to delete it, i would simply unplug the vsv, but would plug the line going to the BACS port.
 
Looking for knowledge on BACS and SICS. Currently cleaning up and simplifying my engine bay.

If I understand it correctly, I'd like to

1. Remove the solenoid for SICS and connect that directly to vacuum, for constant vacuum.

2. Remove the solenoid for BACS and either connect that to vacuum or run to atmosphere.

Questions:

- My 1HDFT JDM spec with EGR has no manual diaphragm for BACS. How does it sense the altitude? Is there a pressure switch inside the orange solenoid?

J1PNlwN.jpg


- I live at about 6000' and mostly travel/wheel from 4000 - 10000'. Would it be beneficial to hook up BACS to constant vacuum so that it's always "on"?

- OR am i overthinking it and should I just leave the stock setup? I'd love to simplify if possible.

Thanks
 
euclid said:
For the short term i am not. Debating keep the BACS and the SICS in place.
Click to expand...
I deleted a bunch of stuff. The only thing I left is BACS but I feel like I could probably get rid of that too.

It's a very simple setup now, I could draw a diagram for you at some point. I need to go look under the hood again but I basically have vacuum/boost lines going to BACS, boost compensator, and a boost gauge. That's it. Cruiser runs well.
 
ikarus said:
I deleted a bunch of stuff. The only thing I left is BACS but I feel like I could probably get rid of that too.

It's a very simple setup now, I could draw a diagram for you at some point. I need to go look under the hood again but I basically have vacuum/boost lines going to BACS, boost compensator, and a boost gauge. That's it. Cruiser runs well.
Click to expand...
No need, thanks for offer. I left he BACS and the SCIS. Gonna post up some pics and video i took soon.
 
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