4BD!/2 Shutdown Actuator Wiring

astr · Apr 14, 2008

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.

carcrafter22 · Apr 14, 2008

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

hayes167 · Apr 15, 2008

Thanks for the footwork!

Dougal · Apr 15, 2008

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.

astr · Apr 16, 2008

Dougal said:
...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.

Shanker · Aug 30, 2009

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

astr · Aug 31, 2009

I'm away from my manuals and trucks but expect to be back tomorrow and will look further into it.

Shanker · Sep 3, 2009

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.

bush65 · Sep 3, 2009

Shanker said:
... 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.

Shanker said:
... 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.

Shanker · Sep 4, 2009

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?

bush65 · Sep 5, 2009

Shanker said:
...

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.

coog · Sep 4, 2009

You start with the cable pushed all of the way in, pull to kill.

coog · Sep 5, 2009

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

Dougal · Sep 5, 2009

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.

coog · Sep 9, 2009

Thanks, John.Nice to know the extras I'm saving can be used for either motor.

gijohnson · Oct 9, 2011

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?

Dougal · Oct 9, 2011

I don't think the 4BD2's have fuel enrichment. They rely on the glowplugs and higher compression ratio for starting. If it's a 4BD1 cable pack, then just find the wire that pulses the second selenoid.

nexxussian · Oct 9, 2011

John, did you ever find out if the 10.5 mm plungers you had sourced would work in the pump for the 4BDs?

Please forgive me if you've posted that and I missed it.

Dougal · Oct 9, 2011

I don't know if John is currently around to answer, but I think that was negative with the bigger plungers but more rack travel was able to give him the fuel he wanted.

Randy has some solutions for these pumps more local to you.

gijohnson · Oct 13, 2011

I'm trying to figure out how the fuel enrichment works. My 4BD1T appears to have a fuel enrichment cable operated by the same unit that operates the fuel shut off. I wired the fuel shut off as depicted in astr's diagram at the start of this thread.
It works great at opening the fuel shut off and also opens the enrichment lever, but once the fuel shutoff is fully opened the enrichment lever springs back to it's resting position.

Does it require adjustment to get the enrichment lever to stay open?

Dougal · Oct 13, 2011

The enrichment lever pulls out the fuel rack and latches it there before returning to it's original position. This latch is released by the governor when the engine gets above cranking speed.

Starting fuel injection rates are much higher than any while operating.

nexxussian · Oct 15, 2011

ASTR, yeah, I mis remembered (tired when I posted that, not that a commonrail 4BD wouldn't be cool too

) I was thinking of the 4H-E-1TC (always screws me up that E doesn't stand for electronic :emb: ).

I'll post a correction for that in an edit in the previous post so someone searching for info on those doesn't get a bum steer.

gijohnson · Dec 25, 2011

The enrichment lever pulls out the fuel rack and latches it there before returning to it's original position. This latch is released by the governor when the engine gets above cranking speed.

Starting fuel injection rates are much higher than any while operating.

My start up enrichment doesn't seem to be working. The cable pulls the lever back but it doesn't latch; it springs to its resting position. Anyone have any ideas.

Dougal · Dec 27, 2011

The latching is internal, the external lever returns to it's resting position. You can pull the governor housing off and take a look if you are mechanically inclined.

gijohnson · Dec 27, 2011

Thanks for the insight. I'll check it out.

Burning Oil · Feb 18, 2012

Just finished up my swap. A 4bd2 in a 94 Suburban. Very little detail thing to do still, like the engine shut off. Thanks for posting the info.

dontoy · Nov 12, 2013

Andy and Co,

I just wired up the fuel cut off actuator on my 1992 4BD2T. I did use a relay that has the 87a prong. My question is it seems to work opposite of the way I expected. Can’t remember how it worked prior to pulling the motor. When I have the wife turn the ignition key to the run position the actuator runs the cable out, not in as I thought it should. Is shut off function such that when cable is slack/not connected the valve is in the run position? And when key is turned to off position actuator pulls the cable in against the spring closing the valve. Seems like for a fail safe operation if the cable came off/failed the fuel valve should close due to the spring not open.

Do I need to reverse the 87 and 87a wires or is this normal behavior?

Any help is appreciated.

Thanks,

Don Ferguson

astr · Nov 12, 2013

IIRC, the spring pulls the lever to the run position so you should be OK. I'm going from memory so I may be wrong.

astr · Nov 12, 2013

Using the Wrong Relay

I've noticed that some people are having a problem because they are using the wrong relay. Be sure that the relay that you use has the 87a contact. This is the normally closed contact. I see that some of the relays have two 87 contacts which are wired together inside the relay. These will not work! You need both an 87 and 87a contact.

dontoy · Nov 12, 2013

Ok thanks Andy. Yes on mine when key is run position cable is slack and valve spring has rotated arm toward firewall.

thanks again,

Don

dontoy · Nov 13, 2013

Dougal.....thanks that answers that mine seems to be doing what it should then. Got the DSL-1D tach converter hooked up today. Used the sensor in the pump cover for the signal. Tomorrow I plan to hook up boost and EGT gauges and modify fan shroud.
thanks again,

Don

bush65 · Nov 13, 2013

Is there a work-around with the tacho converter for only 25 pulses per engine revolution?

Without looking up the details I seem to recall that the minimum pulses per rev, for calibrating the converter, are somewhat greater than 25.

I would like to do similar and was wondering if there might be a work-around like setting it for 8 cylinders instead of 4.

mechanic68 man · Mar 2, 2015

I have a 2006 ford expedition with a 4bd1t in and running I cannot figure out how to wire up the stock ignition switch to my ignition switch in the truck any help would be greatly appreciated or the wiring diagram of that extra selenoid

4BD!/2 Shutdown Actuator Wiring

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