2H Diaphragm, what could have gone wrong? (1 Viewer)

[ColumbusHJ60]

Longtime lurker, first time poster. Reading threads on this forum is how I came to learn my truck needed an IP diaphragm and several other things I've been working through. This is my first Cruiser and my first Toyota Diesel. Far from my first Diesel, but the way the 2H IP works with the diaphragm setup is quite different to the Mercedes diesels I am used to.

Truck is a 1988 HJ60 5speed I imported from Japan about 2 months ago. Truck has always run well, but I'd noticed black smoke, a high idle, and a "flat" spot in the powerband around 2000-2500 revs. Reading on here, textbook torn IP diaphragm.

Now, Toyota USA would not sell me one. I had to give them a copy of my import documents and my title to get oil filters out of them, but they would not sell me the diaphragm. Ended up buying it from AllFourX4 spares in Australia.

Read a couple write ups on here, and removed my diaphragm




As you can see it was totally trashed, about a 1" tear in it and multiple holes and cracks.

While I was working I kept the drain plug on the side of the pump open to get all the old oil out of the chamber. Install went well, made sure I had it aligned correctly with the alignment tab down, spring and shims are in the right place, cover is centered and tight, didn't drop the washer or 8mm nut into the IP.

Start the truck up, runs really smooth, but idles at 300rpms. Look at the idle adjustment screw, its wound way out actually not touching the throttle arm at all and there are lots of the tool marks on the locking nut. I assume someone screwed with it fighting down the high idle from the torn diaphragm. So I adjusted it back to the 650rpm at warm idle spec I found on here for manual trans 2Hs.

Go for a test drive, zero smoke. But ZERO power. Truck has no power at all, could not get above 40mph in a place the truck used to crest 60mph.

So, here is my question. Do you think someone adjusted the fuel screw to lean the truck out trying to fight how rich it was running? It's pretty obvious someone did that to fight the idle down. My reading tells me that fuel adjustment screw is the capsule on the IP with the safety wire near the top right bolt for the diaphragm cover.

Is there anything I could have messed up in a diaphragm install?

Are there any other issues I should check for?

Are there other mixture adjustments someone would have gone after?

Is there any rule of thumb to making adjustments? I would hate to melt a piston. I do not have an EGT gauge on the truck, does the 2H have a test port where you can put in an EGT gauge for testing/tuning?

Thanks in advance!

 

[ColumbusHJ60]

This is far from an exacting science, but, there are tool marks on the 3 holed locking ring on my fuel adjustment and the adjustment appears to be maxed out on the way in, which I understand to be leaning out the mixture.



Looking at other pics I've found on the forum, most peoples seems to be more like half in, half out.


(I am pretty sure that picture is a 3B, but looking at lots of pictures of 2H and 3B adjustments, no-ones is turned as far in as the one on my truck)

 

[gerg]

Congrats on changing the diaphragm. It's a finicky job. Your fuel is dialled way back. Trouble is now tuning it without an egt gauge is tricky. Id turn it 1/2 turn out and test until you get enough power to get your 60mph but keep in mind that egts can be high in the absence of a smokey exhaust. If someone played that much with the idle and fuel screw I'd be checking the timing marks as well.

 

[Tapage]

IMHO EGT gauge it's basic playing with fuel adjustment ..

with that important note in my experience my 2H will go water temp up fist than EGT on dangerous levels ..

 

[ColumbusHJ60]

Incredibly unscientific per usual, I could see corrosion on the bolt that showed where it used to be. Adjusted it to there, drove it, got a little black smoke, turned the fuel down a bit, no smoke. Truck feels better than it ever has, and with the torn diaphragm the truck actually felt really pretty good when I first got it.

I was going to do diesel purge, change the fuel filters, and clean the inlet screen I have read about (if its on the later 2H), and recheck for smoke.

 

[gerg]

All good stuff to do man. Do double check the timing stamps on the side of the fuel pump. Also incredibly unscientific but give you a place to start as far as timing goes. Shoot a pic up. They are simply two stamped lines. One on the fuel pump and a corisponding one imediately adjacent to it on the front cover. Would have been nice if Mr Yota gave some sort of number or even two lines to gauge degrees, but no! Who need that stuff anyway when your stuck in the jungles of Borneo with the stock tool kit with no fresh water and drinking your own urine....

 

[ColumbusHJ60]

Sorry I have not replied to this thread, the truck is driving much better with my rough adjustments, maybe a little down on power at higher RPMs from when it was dumping all of the fuel, but around town its much nicer and no more lane clearing black smoke behind me.

I need to buy an EGT gauge for another diesel project car so I was considering adding a tapped hole to this manifold for a temporary hookup of an EGT gauge to try to get it dead on, when you've only got 105HP or whatever the 2H makes, you don't really want any of them to go missing.

 

[Tapage]

105 was at the plant at the flywheel and new .. I guess my 2H can put something like 60 to the wheel at this point