Familiar with Isuzu NPR cab/chassis with 4HE1 engine? No start

[fastline]

Bought this 2003 not running. Guess it just died for prev owner. They had a shop look at it and quoted and entire new fuel system but I can find no evidence they did a single thing to it. Not even pull the fuel filter. Curious if anyone has experience with these? Wait to see if any knowledge here before I rattle on.

 

[thepumpguysc]

DONT TOUCH THE INJ. PUMP.!!
Unless timing it to pull it off..
That’s the best advice I can offer..
The injectors are serviceable tho..

 

[fastline]

DONT TOUCH THE INJ. PUMP.!!
Unless timing it to pull it off..
That’s the best advice I can offer..
The injectors are serviceable tho..

Well, let's assume I condemn the pump, do you have any procedures prior to removal? I intend to open the bleeder screw on the top of the pump to attempting priming when it gets here, but I don't intend to blindly mess with the pump until there is reason and a plan.

 

[heymccall]

Finally killed an 4HE1 on one here. Definitely the injection pump on ours.

Let's start with yours, though.
There is screen in the top of the water separator mounted by battery, that is overlooked by many. Remove bowl retaining ring and drop bowl and Oring. Now, spin off the diffuser and pull off screen. If it has a steel tank, tank rust can block that screen (happened on many of mine).
It may behoove you to simply remove the separator and place it in a vise. If the retaining ring is seized, you'll have to replace it and know that most aftermarket separators don't have that screen (but, with creativity, you can move the screen over).
Next, once cleaned out, replace engine fuel filter, open bleeder on engine fuel filter and unscrew primer handle and pump till clear of air.

Another killer on mine is the fuel stop. When key is turned on, stop cable must actuate. This cable is independent of throttle cable. The actuator is like a windshield wiper motor, so, at key on, <whir> for a second along with cable movement. Similar <whir> at key off along with cable moving other way.

Final killer is the catalytic converter muffler. If plugged, engine will run up to 10 seconds and peter out. If attempted to restart right, it won't. If left sitting 30 seconds, it will give up to a 10 second run again. Cut muffler to exhaust brake bolts, leave a gap and restart engine. Should prove plugged muffler.

 

[fastline]

OK, so just talked to owner and I guess it started in the morning, then started to sputter, the died. They checked the fuel separator and bowl was dry! All good signs of a simple fuel delivery issue. Yes sir, I noticed what looked like a screen at the top of that bowl. When it gets here, I will make that the first thing to check.

But on the cable you mention, this does have a fuel shut off solenoid on the pump, but you are saying there is another shut off cable? Truck is not here yet so I am just trying to get my bearings.

 

[fastline]

Also @heymccall , you say you killed a 4HE1? What happened and how many miles? I am trying to learn the limits on the engines and fuel systems. We have no way to know if the pump or injectors have ever been changed.

 

[heymccall]

I've got 4 of them. The rest are 4hk1 (common rail injection).
The 400k mile 4he1 unit that slobbered out the exhaust finally gave up its injection pump. Between the $4k injection pump, engine slobbering (rings from rusted through air filter housing years ago) and rear frame rot, I put that one out to pasture.

These things are nearly bullet proof, though. Keep oil and fuel, along with cleaned air, in them and you're good to go.

The shut off is only a lever, actuated by a cable. Cable no move= no go.

Last one I pulled injectors on, at 250k miles, had them test good. It had restricted steel line from tank to separator.

 

[heymccall]

 

[heymccall]

That gizmo that you "think" is a stop solenoid is actually part of the rack control. Do NOT remove it. It will NOT go back in WITHOUT pump disassembly.

 

[thepumpguysc]

Lol… excellent advice..

 

[fastline]

LOL, I try not to touch unless I know. Let me drop the update. After getting details from the seller, I had more focus on the issues, and I had it running in 15min. I was going to open that separator but decided it had fuel in it at the moment and I want to see if I can make it sing first. No one even attempted to bleed the system! The primer plunger was puking fuel all over but it did the job, I primed the pump bleed screw, then the banjo on the filter housing because that stupid thing does not have a bleed screw.....wtf....

Anyway, I resorted to cutting the spanner nut on the separator to get it apart and I found the smoking gun. A huge glob of nasty in there that has probably existed for years. It must have finally lodged just right and blocked fuel flow. I have a new separator coming.

Engine sounds perfect. There is a touch of blowby off the down tube but no freight train. Exhaust is clean.

NEXT ISSUE. As I ran through the rig, I realized whoever they use for their maint checks is scamming them because there are chunks out of the belts, and the waste gate rubber tube is rotted off! It is puking boost air there and the waste gate rod does not want to move! I'd like info on that! With gentle pliers, it seems like the arm wants to move clockwise, but not counter. I am not sure if that means full boost and it just can't dump boost, or ? What is further annoying is they made that air can just so you can't even remove it!

Other than that, I am just combing the system right now. AC does not work. No charge in the lines but I can see dye so someone was chasing it. I also do HVAC so I guess I will dig into that. I don't have high mode on the fan controls so I am trying to figure that one out. Usually high kicks a relay for full voltage but I am not that far yet. Nothing is labeled so I would be guessing.

 

[heymccall]

PM your email to me. I has digital book that answers most engine questions.

 

[fastline]

PM sent boss! Thanks for your help! I am now trying to find a few upgrade items as this will probably stay in the fleet and it needs a tune up! Wheels sims and LED headlights are what I am chasing at the moment. Did I mention cheap? lol

 

[fastline]

Oh the joy of junk parts.. Got the new water separator.... China.... Looks good. Could not get the spanner nut off at all so said screw it. Thought I noticed a little fuel around the spanner but seemed to stop. However, fired the truck and could see air in the fuel bowl. Bottom line, I chopped the new spanner nut off the new separator because it was FUBAR and I wanted to see that disaster. They galled the shi* out of that nut and the bowl was not tight and sucking air.

Fun part is I got to chase my tail before circling back to that stupid separator. Thought we might have a plugged line, empty fuel tank with bad gauge, etc. In the end, I removed the new separator that was mostly full of fuel and tilted it sideways slightly and fuel came out of that stupid nut. If fuel can come out, air can go in.

Thanks again China! Or OEM for 10x the price. Is there not a middle ground anymore?

 

[OzDozer]

Re the lack of bleed screw on the fuel system - most Japanese diesel engine fuel injection systems do not have a bleed screw, you just pump the primer and it pumps fuel through the whole system and bleeds air out the return line.

 

[heymccall]

Isuzu 4H Series Introduction

Since there isn't a specific area for the newer engines, I posted this here. I'll cite reference where I can. Most of the following information was pulled from the following thread: http://forum.ih8mud.com/diesel-tech-24-volts-systems/157856-isuzu-4he1-swap.html Manual with specs here...

www.4btswaps.com

4btswaps has lots of info on the 4he1, if you dig a bit.

 

[heymccall]

Wait until you need a wheel removed. Aside from being Budd nut style, with LH & RH threads on opposite sides, the inner hollow nut on the inner dual has a tendency to gallon to the outer nut. And, most tire shops don't even have the correct combination socket on hand for normal removal. If the inner nut stays with the outer wheel, I use a 1-5/8 combination wrench thru a hand hole, and a 15/16 12 point socket with a 3/4 gun to separate the two "nuts".
Oh, and even if they has the correct socket, most tire shops don't tighten them sufficiently.

 

[OzDozer]

I always use a sniff of Never-Seez on the threads of Japanese truck wheel studs, sure saves a lot of pain and aggravation from galled threads.

The threads are clearly marked with a big "L" or "R" on the outer end of the nuts, I don't know how anyone could miss that.

 

[fastline]

As I mentioned to mccall, I have found a turbo leak where the gasket has failed between the exhaust manifold and turbo housing, if anyone has experience how sucky this will be? Should I just order a new turbo now? I am imagining breaking every single bolt. I know CAT stuff has always surprised me so maybe Isuzu? I am trying to figure out if I start with the dotco now or make an attempt?

Ideally I would like to just unbolt the turbo, replace gasket, drop back down and go. But thinking that is NOT likely. I will just braze the damn turbo on and be done with it.....lol

 

[heymccall]

Here, in the rust belt, with a little patience, I have successfully unbolted the turbo from the manifold, on several. I have not, however, ever been successful at removing the downpipe. If you undo the first exhaust hangar, and, of course the turbo to manifold hardware, you can slip in a new gasket.
If you're not in the rust belt, you may have it even easier.