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Hitachi, I thought they made Vibrators.


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#1 Jrüdorf

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Posted 05 May 2017 - 11:35 AM

I have a 1985 Z24 backed with an Automatic transmission Fleet Owned 720.
I had just replaced all 8 spark plugs, wires, both ignition coils, cap and rotor. She was running like a dream..when the next day she was stolen almost imedietly after I had started her, so she could warm up, seeing as how it was -35°F outside that day.


After getting my truck back, it wouldn't stay running smooth once the engine became hot. (Standard running temputure) first start of the day, everything would be fine, until it gets to running temputure, then it develops an intermittent random sputter, almost akin to a Misfire.

If I shut the engine off while at running temp, it will not restart easily.
The engine will crank, but it acts like it is flooded and can't breath. After a few seconds I stop, wait a few minutes, and try again. It will come to life after sounding like a .38 cal was fired-

(cops have shown up at my house multiple times since my truck was stolen, "responding to gunshots" and I'm like "you guys have my gun in your evidence locker, the sound reported was my truck")

-it will run with coaxing (holding the pedal down 1-200 RPM higher than flat idle) at stop lights it will cut out upon acceloration almost as if it is not getting enough Air.

Now, mind you, this is only while the engine is hot, or warm.
Dead cold, (several hours of sitting dormant) it starts right up and runs like a dream, until it gets hot.

I decided with help from the Nissan 720 Shop Manual the first step was to check the Carb.
I saw that the plug was still covering the mixture screw, so I decided to check the rest of it. I found the accelerator cable was stretched 4cm. I found an armature sheered off, and the diaphragm in the Auto Choke was shot.

I decided that the best thing to do at this point would be to purchase a new one, being the broke ass northern'er I am, I bought the Ching Brand off FleeBay.
seeing as how the truck is a proud member of the Quarter Milion Mike Club, by having 350,000 miles on it, I was not going to be assed into buying a 3-400$ Weber.

So, new unit came in, and I noticed several small differences between the Hitachi and the Ching.
The Ching has No emissions system parts, like fuel air ratio sensor, a few vacuum lines and a breather line.
So I installed plugs on the other vacuum units in the truck that connected to the carb, and then fired her up.
After 20 second I smelled a Lot of gasoline, and the truck started acting bogged. I immediately killed it, jumped out and inspected the engine, gasoline everywhere from the top of the carb.

The float was stuck open allowing the fuel pump to continue filling the bowl.
I removed the new carb, brought it back home adjusted the float and now I'm wondering if anyone else has used the OM Replacement style carb.

I'm also wondering if my trucks electrical system is confused since the Hitachi has several wires in its harness going to different seonsors, but the Ching only has 2 wires, one being red, going to the anti deiseling solinoide, the other being Blue and going to the auto-choke.


Also, I'm wondering if anyone out there has any Hitachi parts laying around, mainly the cover for the float.
Ching brand comes with a Flat Float Cover, without the window. My Original Carb, also, was missing the window, as if someone had already once worked on it previously and replaced the cover.


1985
Z24 720
Automatic
Regular Bed
Standard Cab
Bucket Seats
350,000 mi.

#2 flatcat19

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Posted 05 May 2017 - 12:03 PM

Title made me laugh.


I think this guy will fit in nicely.






Post pics before the locals get unruly.

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#3 KELMO

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Posted 05 May 2017 - 03:18 PM

^^^This X2.

And I see what you did there.....fit in nicely. That made me laugh harder than the title.
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#4 datzenmike

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Posted 05 May 2017 - 04:45 PM

First I would put the old coils back on. They seldom actually go bad and now you have two unknown sources of problems.

 

Check all eight plug wires go to the correct plug. Not saying you got it wrong but it was stolen and messed with.

 

Check the each side has spark. Pull a plug wire of intake and exhaust side, stick a plug in the end, lay on a grounded surface and crank the engine over. Got two sparks???

 

Set the valve lash. Intake and exhaust are 0.014"

 

What does "I found an armature sheered off" mean?????

 

" and the diaphragm in the Auto Choke was shot" There is no diaphragm on or in the auto choke so not sure what you mean.

 

You had an electronic feedback carb with an oxygen sensor in the exhaust. You car chuck it and run a simpler one with just the idle cut and the auto choke. The truck won't know the difference.However this carb sounds like a piece of shit. Makes that Weber look pretty cheap.


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#5 Jrüdorf

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Posted 11 May 2017 - 01:10 PM

Yeah, all plugs and wires are good and go to the right place.

The truck has 350,000 miles and those were the original coils. It was Very obvious they needed to be replaced. The housing was rusted through on one coil, the other had rust and was deforming from heat.

It was stolen and driven less than 300 feet. I had eyes on them the whole time.

Metal expands when hot and contracts when cold. It was -30 outside, my engine was FRESHLY started, like ran for 10 seconds. It takes 30 minutes of Idleing before the engine is warm enough to drive without damaging the engine here in Alaska.
Bitch jumped in it as soon as I started it and walked back inside because it was ColdAsBalls, 'feel me?

She floored it, to the point where when it was leaving my driveway it sounded like it was running on One piston.

Now, whenever the engine gets warm, it acts like a pile of dick.

And if it is shut off while warm, it turns over, but won't start. After 3 or 4 revolutions it will back fire, with the equivalent blast of a .30-06 which, in Alaska, makes people draw firearms at you because they hear a gunshot. Not a backfire, because no one drives Chitty carbenated rigs.

#6 heywier427

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Posted 17 May 2017 - 10:57 AM

Possibly a headgasket weep?

 

Wrap a rubber glove over the radiator fill, with the cap off, and start the truck.

 

If the gloves fills up in less than a minute, its leaking.

 

These trucks need the head re-torqued every 100k, or less.  

 

Was the previous owner not retarded, and fixed things, or was it on its last legs with ducktape and zip ties as structure?

 

One of my turds V

 

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#7 heywier427

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Posted 17 May 2017 - 10:59 AM

Actually, after re reading, backfiring is flooding.

 

Make a fuel bowl door out of ducktape :) 


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#8 Charlie69

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Posted 18 May 2017 - 08:21 AM

Ching is and was a waste of money.  The factory carb you have has 6 wires on it because it is monitored and regulated by the ECM.  I put Webers on my 80, 85, and 86 720s.  You will like the Weber 32/36 DGEV if you do not by the Chinese nock off.


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#9 Jrüdorf

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Posted 18 May 2017 - 12:14 PM

Ching was 60 Dolan in the end. I can't afford any of that nice shit.
Anyways, the problem has been ruled into the catagory of a Vapor Lock.
So what do.
As for condition, it was a Fairbanks special.
Bits of duck tape and zip ties everywhere, White shag carpet floor mats on a painted fooor pan. Wiring harness stripped to Bare Essentials when I bought it.

#10 datzenmike

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Posted 18 May 2017 - 04:24 PM

Not really hot enough for vapor lock.

 

The carb should have a small glass window on the front. When running have a look and see if the gas is level with it. Take the top off the air filter and watch to see if gas is dripping into the carb when running at idle and after shutting off.


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#11 Jrüdorf

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Posted 19 May 2017 - 10:40 AM

So, neither my Original Hitachi nor the Replacement have the window on the bowl. There is no gasoline overflowing the bowl.

#12 Jrüdorf

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Posted 19 May 2017 - 10:41 AM

And like I said, once I shut it off when it's hot. It will not start again.
Which, is Vapor Lock.

#13 captain720

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Posted 19 May 2017 - 12:40 PM

Actually when I first got my 4wd it would faurt and die like running out of gas and act vapor locked when it got warm couldn't start it back up. And I would get epic backfires. It was the ignition control module.

Not always vapor lock is all I'm saying here.

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#14 datzenmike

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Posted 19 May 2017 - 04:44 PM

And like I said, once I shut it off when it's hot. It will not start again.
Which, is Vapor Lock.

 

No. It could be vapor lock but it can be other things. Timing too advanced, valve lash too tight, over heated coil, flooding carb, engine over heating, bad starter.


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#15 captain720

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Posted 19 May 2017 - 05:26 PM

No. It could be vapor lock but it can be other things. Timing too advanced, valve lash too tight, over heated coil, flooding carb, engine over heating, bad starter.



Yup Dmike that is exactly what I was trying to say.

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#16 Lockleaf

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Posted 19 May 2017 - 07:21 PM

If it's vapor lock, setting a bag of ice against the carb bowl will fix it. Try that, eliminate vapor lock, move on to the electrical problem likely causing the issue.

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#17 datzenmike

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Posted 20 May 2017 - 06:37 AM

The 720 is not known for vapor lock. It's not warm enough (certainly not in Alaska) for that. Plus it has a return line.


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