Starting a fresh engine/IP and inj change

[Missy Good Wench]

I have been reading posts from several here that have had issues with getting a fresh engine and or an engine thats seen an IP and injector change started again.

FOR A DS4 system DB2 very similar

The process is simple.

The diesel system is a fuel system designed to run completely air free.
This is not all that different that your brake system (well actually a lot different) in that air compresses and fluid does not.

The Injection pump pushes fuel through the lines to the injectors until it reaches about 2000 PSI and then the injector POPS open and the fuel sprays into the firing chamber.

When starting fresh the system is full of air and this has to be removed before the engine is going to run.

Turning the engine with the starter is about the only option that we have to do this.

Long crank times with the engine fighting compression will kill the starter and the batteries as well as your patience.

Here is the easiest way to get this task done without killing anything.

I will skip some of the obvious steps like "Hook up batteries etc"

Depending on your rigs model year use what ever procedure is needed to get the lift pump running.

Get fuel to the Injector pump inlet (Hose in a cup until fuel flows.

Hook up fuel line to IP

Turn key switch to "ON" only

Run lift pump for approx 45 seconds or so. This will actually purge fuel through the IP and back to the tank.

Now WITH ALL GLOW PLUGS REMOVED (the RH side can be easily accessed via the inner fender access hole with tire off)

NOW
Have a helper watching the glow plug holes (LH side is easy)
Spin the engine over (will spin fast with plugs out)

Usually takes about 30-45 seconds to have fuel mist coming from the plug holes.

Stop and shut off the key switch.

Install the glow plugs and hook up the wires.

Take a deep breath ):h

Turn the key on and allow the glow cycle to complete.

Turn key to start and crank the engine over.
The engine should start in 3-4 seconds providing that all the goodies are working properly. (glow plugs, relays etc)

The engine should start right up and run fairly well using this procedure.

Every set of injectors and every IP is slightly different but thing should go smooth and fairly quick without the usually hastle of bleeding the lines and fooling around with a smokey rough running engine for 30 minutes.

With the engine spinning with glow plugs removed, the IP does not have to fight the compression to force fuel though the lines and out the injectors.

There are small clearances in the injectors that will allow air to escape readily as long as there is no pressure against it.

The engine will spin at around 400 RPM without the plugs in and this greatly speeds up the process.


I hope this helps any who need to restart an engine that has been freshened and or seen the IP and squirts replaced.

Plus while the engine is spinning without compression (Fresh build) you are getting oil pumped up into the system.


OH to the MODS, If you see fit, maybe this would make a good sticky

Best

MGW

 

[nvmtnlion]

Nice work Robyn! I think it's a good idea!

 

[Brooklyn Tow]

Tip of the week ^

 

[Acesneights1]

Maybe add in that quote from GMCTD about doing it without pulling the glows if one choses. I can testify he was right on.Just so mit's not confusing I had changed only 4 injectors and then started it thinking I would run it then do the other 4. Bad idea...
Here GMCTD goes:

While Ace's gone, blowing the air out of it, lemme 'splain this all again (from the above, fairly certain he ain't gonna pay attention, but fwiw here goes):

He's got three problems:
Left bank
Right bank
PCM

The bank with the old injectors is sloppy, laid back - the bank with the new injectors is tight, on-time

PCM manages idle by varying fuel rate cylinder by cylinder as needed to maintain even idle speed - thus, first sloppy old injector cyl results in extra fuel to keep rpm up - next tight new injector cyl now needs less fuel because of the new injector plus the first cyl got extra fuel - next oi sloppy cyl needs more fuel - next ni cyl needs much less - next oi cyl needs more, etc etc - PCM is headed for 3rd deg black belt PMS as a result of the opposite banks of unmatched old\new injectors, plus two cyls on each bank fire adjacently: 1-8-7-2-6-5-4-3 - thus the noises and uneven idle, not even to mention trapped air bubbles in the new injectors, which ain't gonna inject under most circumstances - thus the instructions to 'drive' it out.............

If he had a scantool, he'd see this as DTC91-98 Cyl Bal Errors, which don't show up on the CEL, plus the varying idle rpm and idle fuel rates, and probably timing variations

Thus, always a good idea to replace all eight injectors at the same setting - MrGoodservice then pulls the OS connector, which disables the variable idle function, which allows the injectors to air-bleed without driving PCM and owner crazy - prollem is, no OS = long-hard-start mode, even more confusing to the novitiate Dieseler, who's already worried sick that he's done something wrong and possibly damaging - thus, the instructions to 'drive' it out........
PartII GMCTD:
Ok - gotcher attention - after installing the rest of the injectors, new set both banks, you can either drive it out, purging the air bubbles, and best method, in this case - or - you can disconnect the OPTICAL SENSOR connector, which is the Service Bay technique - prollem is, that causes LIMP MODE, also known as long-start mode, because thass what it do: takes a long time cranking B4 it will start - but it will quickly (~15mins) purge the injectors in the driveway, not in the garage because of CO

If yer still nervous about it all, do it with new injectors in one bank at a time, may be quicker in the long run, in case something does go wrong - we on the same page?

Yes - GMTDScan Tech was designed for your OBD1 truck

 

[Missy Good Wench]

If you are replacing the squirts it makes no sense to mess around with all the extra work and stress.

Just screw in the fresh ones in all 8 holes and spin the beast up and go.

This is just too darned easy to make such a PITA out of.

Takes only a matter of a few minutes after the new aquirts are in to have the beast road ready again.

Where it gets a tad more dicey is when youhave a spanky new IP that empty plus empty lines, fresh injectors that are also empty.

One can even do the intial spin up with the turbo off the rig just as long as you plug the turbo oil feed line so it wont puke oil all over.

So what if it fires off, a little smoke and noise is all.

Buddy of mine has a mickey mouse pipe with a flange welded to it that bolts to the turbo flange on the RH manifold and sticks up and out over the fender and up in the air.

Makes doing trouble shooting easy and not have all that smoke in your face.

Just like running the engine without the intake manifold. No problemo, Just lock up all the rags and make sure the valley is clean.



MGW

 

[turbovanman]

What about a system with a mechanical pump?

 

[WarWagon]

Just like running the engine without the intake manifold. No problemo, Just lock up all the rags and make sure the valley is clean.

MGW

A CO2 extinguisher is a must if you have the entire intake off the engine.

Otherwise a plywood board that will cover the manifold can save your run away engine if the IP is stuck wide open.

 

[chessie 6.5]

Another easy way to bleed air after bleeding fuel filter is to leave any one injector line a little loose (one that is the easiest to get to). Most of the air will go to this point. Tighten after engine tries to start and fuel drips out.