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Those of you that have swapped the 4BD1/2 motors into other vehicles may have run into difficulty using the OE Isuzu shutdown actuator. The OE wiring requires an extra set of contacts in the ignition switch to operate the actuator. You can either install the Isuzu switch (or one with the necessary additional contacts) or wire in an extra relay. The diagram below shows how to wire this relay.

The relay is a regular automotive SPDT relay. Be sure to get the one that is the "double throw" type also known as "Form C". This type has the additional contact (87a) that is connected to the common (30) when the relay is not powered up. One side of the coil of the relay needs to be connected to your existing ignition switch, to a terminal that is hot only in the "start" & "run" position and not in the "off" or "accessory" positions. If you are swapping this engine as a replacement for a gasoline engine, the connection that was previously connected to your ignition coil should work.
 

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Thats top notch work. Great job. I havent gotten to that part of my install yet but I will copy this for future reference.

Thanks

Randy
 

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Great diagram.
I think that's how mine is setup, it's one of the last birdsnests that I've been meaning to sort out.
The result is dead simple, just earth, batt connection (fused as shown) and to the "on" circuit from your key.

I have had issues in the past with this circuit being back fed from other accessories and keeping the engine alive after the key was removed. This was due to the original installer (who I spoke to a few years back and had no recollection of the conversion) simply picking the nearest wire in the loom which powered on with the key.
The alternator would back feed it and provide just enough power to keep the fuel on. I put a relay into the alternator circuit which worked unless the electric fans were on.

So yeah, take it back to the key circuit and avoid a lot of hassle.
 

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Discussion Starter #5
...So yeah, take it back to the key circuit and avoid a lot of hassle.
On a gasoline (petrol for some) engines, only a few items are hot in both the "start" and "run" key positions => electric fuel pump, ignition is all I can think of. This is the circuit that you want to power the relay. There are a lot of other circuits that are hot in "run" but not in "start" => alternator comes to mind. You don't want to use this circuit.
 

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On a gasoline (petrol for some) engines, only a few items are hot in both the "start" and "run" key positions => electric fuel pump, ignition is all I can think of. This is the circuit that you want to power the relay. There are a lot of other circuits that are hot in "run" but not in "start" => alternator comes to mind. You don't want to use this circuit.
Good point. Well worth checking with a multimeter and some needles before you commit.
But on my vehicle I went straight for the wires out of the key barrell. The "ON" circuit there is still live when switched to "start", but that doesn't mean yours will be.

BTW, I've added this to the FAQ at the top of the page.
 

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The round "female" end of the plug on my Isuzu Shutdown actuator has wired labeled 1 through 6 on the back of the plug. are these wire labels used in the diagram on this thread?

My wires are as follows:

1: Blue/Red
2: Blue/Yellow
3: Blue/white
4: Black
5: Blue
6: Blue/Black
 

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Discussion Starter #8
The round "female" end of the plug on my Isuzu Shutdown actuator has wired labeled 1 through 6 on the back of the plug. are these wire labels used in the diagram on this thread?

My wires are as follows:

1: Blue/Red
2: Blue/Yellow
3: Blue/white
4: Black
5: Blue
6: Blue/Black
I'm away from my manuals and trucks but expect to be back tomorrow and will look further into it.
 

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Discussion Starter #9
The round "female" end of the plug on my Isuzu Shutdown actuator has wired labeled 1 through 6 on the back of the plug. are these wire labels used in the diagram on this thread?

My wires are as follows:

1: Blue/Red
2: Blue/Yellow
3: Blue/white
4: Black
5: Blue
6: Blue/Black
I looked at a couple of different year's manuals and it appears that they use different connectors but the wire colors seem to remain the same. These are the abbreviations that Isuzu uses for the colors:

Blue/Red = LR
Blue/Yellow = LY
Blue/White = LW
Black = B
Blue = L
Blue/Black = LB

All of the shutdown wiring for the years that I looked at only used five wires as shown in post #1 so I don't know what to make of your Blue/Black wire. The earliest manual that I have corresponds to my oldest truck - 1986. I also checked out a 1995 manual.

You state in your other thread http://www.4btswaps.com/forum/showthread.php?t=10355 that the actuator came from a late '80 truck so I would expect the wire colors to be correct. Try hooking it up as shown in the diagram and just ignore the blue/black wire. Let us know if it works.
 

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Andy,

Thanks for loking that up for me. I've discovered that my injection pump does not have provisions for startup enrichment. All my other Diesel rigs had a manual pull-cable to stop the engine, so I believe I'll stick with that for simplicity.

I also like that non-diesel drivers won't know how to start it!


.. know of anyone needing an actuator? I paid $165 for it but I'll take $100.
 

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... I've discovered that my injection pump does not have provisions for startup enrichment. ...
Although it doesn't have the external lever for startup enrichment, the governor does include startup enrichment.

Refer to the pics that show parts around the sensor lever, parts around the torque cam and the governor assy.

The sensor lever pivots about the pin shown about halfway up it's length. The control rack engages with the fork at the top of the sensor lever and causes the sensor lever to pivot. As the control rack travel moves into the pump (more fuel), it's travel is limited by the bottom tip of the sensor lever contacting the torque cam.

When the engine is stopped, the governor spring (via the tension lever) pulls the torque cam fully back (clockwise rotation).

If you fully depress the accelerator pedal while the engine is stopped, the tip of the sensor lever will move under the notch at the bottom of the torque cam. This moves the control rack to the startup enrichment position.

When the engine starts, the governor will try to rotate the torque cam forward (anti-clockwise - the higher the revs, the further it tries to rotate the torque cam). When you lift off the accelerator pedal, the sensor lever will unlatch the torque cam, which can then rotate to the normal position.

... All my other Diesel rigs had a manual pull-cable to stop the engine, so I believe I'll stick with that for simplicity.

...
I would like to have the manual stop cable (no electrics to fail), but where I am the legal requirement is that the engine has to stop when the key is turned off - so I have to use the electric motor with push/pull cable.
 

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That would explain why my Land Rover Diesel has a mechanical stop-cable built into the ignition cylinder! Here in the U.S. vehicles were manufactured right up through the 1980's with manual stop-cables (my 1980 International Scout II with Nissan 633-T)

Does this mean I should start my engine with the throttle wide open?
 

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...

Does this mean I should start my engine with the throttle wide open?
Depends on conditions.

If you require fuel enrichment for a cold start (could depend upon ambient temp), then depress the accelerator pedal fully before starting the engine, and hold it down until the engine is running.

Edit: for your information, most diesel engines don't have a throttle. The air inlet is always open and the governor on the injection pump controls the fuel to give the engine speed commanded by the accelerator pedal position. The air/fuel ratio varies from lean at full power/load (smoke limit is about 18:1) to very lean (could be 200:1) at idle/light load.

Unlike a gas engines which have a throttle to control the amount of air that the engine can have. Then the fuel system controls the air/fuel proportion to be always about 14:1.

Some modern diesels have a throttle, but it is computer controlled and part of the emission control system.
 

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Are the injection pumps inter-changeable beween 4bd1 and 4bd1-t? Any adavantage in using the later model pump in the earlier engine?
 

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Are the injection pumps inter-changeable beween 4bd1 and 4bd1-t? Any adavantage in using the later model pump in the earlier engine?
Externally they are interchangable, but there are differences.
The most obvious being the external fuel enrichment lever/cam on the 1 series pump which isn't there on the 2.
There will be internal differences as well, I'd expect the torque plates (which set max fuel through the rev range) to be different.
 

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Are the injection pumps inter-changeable beween 4bd1 and 4bd1-t? Any adavantage in using the later model pump in the earlier engine?
Yes, they are all 'A' series injection pumps with 'RLD' governors, they rotate in the same direction and have the same mounting on the engine. So physically they can be interchanged.

Governor and timing advance calibration is different - but stock calibration is not likely to be optimum for a modified engine
Some have an aneroid for altitude compensation.
Some 4BD1T's have a boost compensator, and some don't.
It appears that some have different diameter plungers. I have see reports of 8.5 mm and mine has 9.5 mm diameter plungers.
There are 2 different sizes used on the camshafts in 'A' series pumps where the timing advance unit fits. But I don't know if all 4BD1 and 4BD1T injection pumps use the same size - they may well do, if not it wouldn't be a problem if you have the appropriate timing advance unit.

There is a Bosch pump identity number on the identification plate attached to the pump that allows a Bosch diesel shop to find all of the parts and calibration values for the particular pump. So if you knew a number from a 4BD1T pump (there are several different pumps used on 4BD1T engines), then it would be possible to change any different parts like plungers and barrels, torque cam etc. and the calibration could be replicated with a different pump.

Mason (dieselbuggy) posted a pump number 9400230069 (I don't know what engine it was from) that has 10 mm plungers and barrels that will fit a pump from a 4BD1T.

I found a number (101401-7452) for a pump from a Isuzu 4HG1-T that has 10.5 mm P&B that should fit my 4BD1T pump - I should know for sure soon :D

Besides the Bosch identity number and the Isuzu part number, there is an assembly number on the identification plate which can be deciphered to tell the plunger diameter among other things.
 

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Edit...Mason (dieselbuggy) posted a pump number 9400230069 (I don't know what engine it was from) that has 10 mm plungers and barrels that will fit a pump from a 4BD1T.

I found a number (101401-7452) for a pump from a Isuzu 4HG1-T that has 10.5 mm P&B that should fit my 4BD1T pump - I should know for sure soon :D ...Edit

Amazing as always John, thanks.:)
 

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I'm trying to figure all this out. My next project is to get my fuel shut off working. I have a 1991 engine, which I believe has the same 6 wire set up as mention prior. I want to make sure I have all of this correct.

So is the additional wire for the fuel enrichment?
The fuel enrichment is activated by the switch on the accelerator pedal?

Does anyone have a diagram of all of this?
 
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