[astr]

On my 4BD1T, I have three mechanical cables that go to the injection pump: first is from the accelerator pedal and controls the fuel quantity, the second comes from the electric servo motor and activates the fuel shutoff lever to stop the engine, and the third, the mystery cable, also comes from the electric servo motor and loops behind the injection pump and rotates a shaft on the injection pump that is between the pump and the engine block. What is the purpose of this cable? Both my 1985 and 1989 4BD1T engines have it while the '92 4BD2T does not. There is no mention of it in the FSM.

What is it?

 

[Dougal]

That's your cold start enrichment.

It pulls on the cam on the block side of the pump and locks it at higher fuel delivery until the governer turns fast enough to unlock it.
On my engine I adjust the cable stop to get best starting while minimising smoke.

When the key is turned on it should pull once, then relax.

 

[astr]

Dougal,

Thanks! You truely are a wealth of information on thesae engines.

Andy

 

[the88tlc]

4bd1t - first start after rebuild

yeah dougal, thanks for the information about this, I was also curious about this.

I tried starting the isuzu 4bd1T before installing the trans. I had the injectors done, but not the pump. I did not remove the 3 gears (pump, idler, cam) only the crank and clearly marked a crank tooth, and a idler valley. new filters. rechecked the valves. Bled the line to the pump, then also bleeding the high pressure side. should just pop right off?

I tried to start it on the chain and stand, and could not get it run smoothly. we would pull this cable then start it, glowplugs on, and it would only rev up, then die. seems like it is starving for fuel.

fuel injection pump problems? air in the lines still? Lift pump? Or is there something going on with this enrichment cable?

 

[Dougal]

The cold enrichment cable is a way of manually over-riding the governers fuel delivery.
If you pull on it you can keep fuel flowing even when the gov doesn't want you to.

But it sounds like you've got air in the lines. Last time I put my engine back in the fuel lines, injector, filter and pump were completely empty. It took a lot of priming to get it running and even more to get it running smoothly.

 

[the88tlc]

isuzu injection system priming

thanks for advice. sounds like I need to find one of those actuators. I have only seen a photo of this in the 'white bag', is this two separate actuators? or one that somehow does both? does it actuate shutting off the engine, and at the same time opens the fuel for the next time the engine is started?

regarding the engine priming. I have not let it run too long, so i wondered if it needed some more priming. i will wait until I get in the truck, get a fuel pump to force fuel up, and a radiator, and try it again.

the engine did run before, so the liftpump and IP were doing there deal before introducing a bunch of air into the system.

 

[Dougal]

Yep the one white bag with two solenoids in it and two cables coming out of it.

 

[briney]

do these engines return to the pump, or to the fuel tank ? if it returns to the pump, it may not hurt to crack the bleeder while the engine is running. just to get any random bits of air out.

 

[Dougal]

do these engines return to the pump, or to the fuel tank ? if it returns to the pump, it may not hurt to crack the bleeder while the engine is running. just to get any random bits of air out.

Return to the tank.
But cracking the lines ontop of the injectors while running seems to work well. Of course if it's running, the air will soon be purged anyway.