what is this wire? 4jg2t injection pump

by **vonzep** » Mon Mar 02, 2015 12:25 pm

It is at the front of the pump between the pump and block.
The front of the motor is at the bottom of the pic
I am looking at starting this motor out of the truck and I think I have the plumbing/wiring figured out except this one.

by **vonzep** » Mon Mar 02, 2015 12:25 pm

Sorry it's 2 wires not one

by **vonzep** » Wed Mar 04, 2015 1:31 pm

Ok can anyone suggest where to ask? ??

by **geeves** » Wed Mar 04, 2015 1:53 pm

At a guess its part of the cold start. Should start without connecting.

by **isuzurob** » Wed Mar 04, 2015 4:48 pm

hard to tell by the picture but looks like the rev counter pick up and wiring

by **vonzep** » Thu Mar 05, 2015 4:13 am

That makes sense on the Rev counter. I energized the fuel shut off solenoid and with a 2 psi electric pump pumped diesel and had a steady drip from the diesel return. My battery was too weak to engage the starter but it should be charged up this afternoon.

by **vonzep** » Thu Mar 05, 2015 11:36 am

Ok killed the battery trying to start it. It really felt like it was going to catch and even had sweet diesel exhaust smell but no luck.

Should I try bleeding the ejector?

by **turnturn** » Thu Mar 05, 2015 7:03 pm

I think, but am not 100% sure, that the fuel cut off solenoid requires at least 9 volts to work.

It wouldn't hurt to crack (loosen) an injector line to confirm that fuel is getting that far. Be careful while doing this as you are dealing with high fuel pressures.

I see that your 4JG2 is in another vehicle, did you keep all the CSD (Cold Start Device), QWS (Quick Warmup System), QOS (Quick On Start I, II or III) systems functional?

by **vonzep** » Fri Mar 06, 2015 2:50 am

I have the motor/transmission/transfer case combo mounted on a pallet out of the vehicle. It's easier to get around on it if there are problems. I have the manual from the link above but it is for a 4jg1t. The cold start stuff is there on the motor but the vacuum lines are missing and the wiring harness was cut. So I have no idea yet of how it goes together.

Even a search for a hardcopy or digital manual of the 4jg2t is fruitless.

by **Roderunner** » Fri Mar 06, 2015 10:43 am

If you have a facebook profile you can join the Australian Facebook jackaroo/isuzu page, which has a free manual that you can download, there are a few variations of the 4jg2, but the basics should be the same, if not similar. Heating the glowplugs might help it to start if ambient conditions are cold, the Australian model engine has 12 volt glowplugs so if yours are 12 volt (it should be written on them in tiny letters/numbers) just give them power for 20 seconds and see if that helps the engine to fire.

by **vonzep** » Fri Mar 06, 2015 11:07 am

WOW. Thank you.

by **turnturn** » Fri Mar 06, 2015 6:33 pm

For your situation the QOS (Quick On Start) system is probably the most important thing to get working. It controls the glowplug timing. There are (that I know of) three variations I, II & III. There are aspects of them covered in some of the manuals able to be downloaded from the Mediafire site.

The CSD is something like a device on your injector pump throttle linkage (wax canister with some coolant hoses going to it) that increases your idle when the engine is cold and also/maybe a solenoid that either advances your injector pump timimg or injector pump internal pressure (I could be wrong about this).

The QWS is made up of the two vacuum operated butterfly valves on your intake tract and exhaust. in my opinion (unless you are in a very cold environment) these are a complete waste of time. I remove or disable these at the first opportunity.

by **geeves** » Fri Mar 06, 2015 6:51 pm

http://www.mediafire.com/view/?32re54asslnsupk

try this just for the engine. The 4jg2 has a few variants though. I think this covers the non electronic controlled injector system. If yours has a big box on the back of the injector pump you are going to have some fun as this is the type with an ecu which I think you dont have.

by **vonzep** » Sat Mar 07, 2015 1:20 pm

The above link wont work, is there a link to the whole book? I hate asking so many questions but as of yet I have not found the resources I need.

by **vonzep** » Sat Mar 07, 2015 1:26 pm

No black box. There is a throttle position sensor, a solenoid fuel shut off on the back of the pump and up front between the block and pump a 2 wire sensor (the picture)

by **geeves** » Sat Mar 07, 2015 3:14 pm

the link does work but the online viewer does not. You have to use the download button on the top right then wade through a sea of advertising to get the file. I just downloaded it with Chrome but 3 full page ads and one surveystistment before the link started. Free service money wise but paid for by the stupid ads

by **isuzurob** » Sat Mar 07, 2015 5:24 pm

to start it you just need fuel, 1 power wire to the solenoid, 2 powers to the starter and 1 to the glow plug rail for 15 seconds and a good earth, the wires you wernt sure about are the rev counter pick up

by **vonzep** » Sun Mar 08, 2015 9:15 am

Glow plugs on for 20 seconds. Strong battery wired directly. Diesel exhaust puffing out the radiator hoses.

I am assuming it is a cracked head

by **turnturn** » Sun Mar 08, 2015 12:39 pm

Or headgasket.

by **vonzep** » Sun Mar 08, 2015 1:24 pm

True. I am waiting on the seller to get back with me as this was to be a "running" motor...

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