The Official 1HD-T/FT Fuel Pump Mod Tuning Thread

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Great. Thanks guys!

I may have confused you with the pump build info. History as follows:

2008: bought truck. Pump tweaks unknown. Rebuilt in 2002. Went bloody well. Blew some soot down low and found EGTs a bit high on the highway. Economy pretty good 11-12l/100.

2010: got pump tuned on dyno. Economy improved. Tuner claimed there was not enough 'low end'. Picked up ~15hp. Ran for 80k. Did 6 month trip with 3.7ton. Reasonable economy; new injectors.

2015: got a bit smoky so pump rebuild. 'Modded' to late model pump specs. Set on bench. A real slug dozen low. Almost no smoke throughout range.


So... I should turn cam back to minimum and perhaps try a little less spring pressure? I have been adjusting star wheel through side but it would be easier to remove diaphragm. Do I just need to take out the spring in the front side to get the pin back in?


Will try and fit AFR ASAP.

Cheers!
Dave
 
Yotahed,
How is your pump going. Have you got an update for the forum?

Has anyone else come across info on the other sights for cummins etc for these secret recipes for internal mods to this pump. The Americans define over the top and there a lot of sled trucks etc pumping out serious power. Surely they have a lot of info to offer other than Aneroid tuning and pin grinds. There is more to power than just max fuel. Need to get it there at the right time and keep it efficient.

To everyone that has contributed… top job!!!

Cheers
Mat
 
I have been tinkering with the pump. I could not really get the travel I wanted out of the old spring (19mm) so had two new ones (26mm and 30mm) made ($35 Cairns Spring works, free plug, good to deal with and can make anything). I also tested the springs to see how the performed under pressure as well as the original spring. Put the data into a graph because everyone likes a pretty picture.

image001[1].webp


Atleast I know exactly what the springs do. Reckon I will end up using the 26mm spring as it gives about 12mm of movement. I couldn't test any higher than 22lb because the cooking scales I used maxed out so there is actually a few more mm of travel in the two custom springs. The original is just about maxed. and to get the university to test them is about $1000. DOH.

Anyway. With more pin travel makes it easier for me to fine tune. I might change later to a stiffer spring that will help tune for 24lb. With the longer spring the start height is obviously high as is the height at which it fully compresses but you get more travel inbetween only 8mm for original and over 10mm for the 26mm spring.

I will be running about 24lb boost and these spring will handle no drama. You can get custom springs made easily and then its just trial and error.

Smoke screw removed and a ground down bolt that does nothing inserted. Starting position is completely determined by AFC which with the bigger spring is completely wound down to the base. More fuel will be needed. I will keep adjusting until too smoky off boost. Wind up AFC to lean out AFRs until more boost kicks in.

On a side note I have been trolling through the various forums: cummins, diesel performance, turbo dodge etc. These guys have RIDICULOUS pumps. I got the diesel shop to set mine to 50% more fuel or roughly 93cc. They are getting pumps pushing over 600cc on some 1st gen cummins.:eek: They are not daily drivers though, but still.

Baffles me why this info has not yet filtered through to the Toyota fans. Fear perhaps?
 
Does anybody know the correct part number for the boost compensation spring for hdft there seems to be like 5 differnet part numbers just on hdft.. sorry if this has been mentioned cant go through 20 pages right now.. My old man left his out last time he made an adjustemt and now it has come to him he cant find it :( 50000km later
 
Tks how does this diagram work cant scroll these are obviously not toyo part numbers
 
There is nothing to scroll. that is the info Bosch sent me. At least it is a starting point. I tried getting a list of different available pins but they won't help. I had imagined a nice little picture with all the available pins. I pulled one out of an old Nissan it had 15.5 stamped. Very flat taper. One out of a rover was similar with a really long flat taper to match the longer Spring.
 
Anyone know where I can find a new AFC pin that hasn't been ground? Let this be a reminder to only run hardened fuel rods.... yes, this is mine... no, I did not modify it, whomever owned the truck before me in Japan did.

 
So much of the AFC pin was...destroyed... by the hardened guide pin, that it actually created a metallic PASTE that then JAMMED UP the guide pin, resulting it being completely stuck. I had to use a ****ing hammer to loosen it, then cleaned the AFC pin sleeve slowly using wd-40 and about 3,000 q-tips... then worked the guide pin back and forth back and forth lubing it with wd-40 until it moved freely. After putting the cap and spring back in I was pleased to see the guide pin moving like it should.

I do like the modification they did to the back of the AFC, which allows you to put the thing in 180 degrees opposite and then rotate it into place without having to remove that front plug/spring to release tension on the guide pin.
 
First thing to do was to cut a ramp into the new pin for easy installation. Luckily one of my friends has a lot of very fancy milling equipment and made the job very easy :):banana: We cut the ramp in at exactly 1/4 of the pin...say, "3pm"... allowing me to use either the "stock, oem" face or the more aggressive modified face.

IMG_20160111_213853.jpg


IMG_20160111_213858.jpg


IMG_20160111_214609.jpg


One thing we did check, he had some 4140 10mm rod... and compared it against the 2 AFC pins. The stock, but modified, one from Karter, and the completely aftermarket one that was in my truck when I brought it over from Japan. Both AFC pins measured at 11mm, not 10mm. In addition to that, the pin from Karter and the 10mm rod my buddy had were significantly stronger than the aftermarket pin from my truck.

IMG_20160111_213418.jpg


Measurements, because I know you guys like that...

IMG_20160111_213544.jpg


IMG_20160111_213639.jpg


Put it back together and marked the most aggressive section of the adjustable "smoke screw" lobe...

IMG_20160111_225856.jpg



Results : At 1/4 way on the compensator adjustment, no acceleration at all. Barely makes 1,000 rpm on full throttle down.

At nearly full adjustment, drives fairly normal. ZERO SMOKE. None. Hardly any on cold start this morning, and once a little warm, NONE. Even while driving down the road and then stomping on the fuel.

Downside, while in lockup, it really has no power. It has to kick down in order to accel even on flat ground. Once boost builds to about 6 psi, it feels normal, even as powerful as the old rod. But until then it's a dud.

I have to play with it a bit more. I have a bit more adjustment with the top screw. I can also play with main fuel screw as my egts don't seem to have been affected. I suppose I could also adjust that star wheel (though I don't want to since I don't know wtf I'm doing with it!) and I suppose I could also auger out the TINY little inlet hole for the air line that drives the compensator as others have previously done. That's supposed to increase response (build pressure on the diaphragm faster, maybe providing better response?)

:popcorn:
 
@asutherland

Augering out the hole will do nothing. Don't bother according to G, I asked about this in the past.

You need to give it more low end fuel by the sounds of things.
Don't touch the max fuel screw. Leave it stock. You can get more fuel out of your pump with a pump advancement.
When you turn your max fuel screw how I understand it it will hit a point where the pump will actually lose pressure inside and the advance piston won't work to how its been properly set. Hense why you can just advance you pump to get more fuel in per stroke (inject more fuel into your engine essentially).

Grease you're pin up put it in. Take it for a drive. Take it out, and take notes how its indexing (start point and how far it travels on max boost.
You want it to travel the full length of the fuel pin if possible.

It won't hurt the pin to run it on the cut section....
What you can do once you have found the optimum spring tension you would like (how far it travels under full boost) You can adjust the cam plate to give it more pre boost fuel. This will help the bottom end out.

Did you have any spacers in your pump that sat against the diaphragm cap and went over the fuel rod like a ring?
Those can be added if you want to limit the fueling up top.

Hope this all makes sense.
 
ForealBoreal said:
@asutherland

Augering out the hole will do nothing. Don't bother according to G, I asked about this in the past.
Click to expand...

Ok

ForealBoreal said:
@asutherland
You need to give it more low end fuel by the sounds of things.
Don't touch the max fuel screw. Leave it stock. You can get more fuel out of your pump with a pump advancement.
When you turn your max fuel screw how I understand it it will hit a point where the pump will actually lose pressure inside and the advance piston won't work to how its been properly set. Hense why you can just advance you pump to get more fuel in per stroke (inject more fuel into your engine essentially).
Click to expand...

Too late, it was heavily modified (with no indication of where stock was) when I brought the truck over from Japan. I have zero idea where the "stock" setting is on the main fuel screw. :(

ForealBoreal said:
@asutherland

Grease you're pin up put it in. Take it for a drive. Take it out, and take notes how its indexing (start point and how far it travels on max boost.
You want it to travel the full length of the fuel pin if possible.
Click to expand...

How do I do that? Put paint pen on the pin?

ForealBoreal said:
@asutherland
It won't hurt the pin to run it on the cut section....
Click to expand...

I already have it running on the cut section. I didn't even try the stock.

ForealBoreal said:
@asutherland
What you can do once you have found the optimum spring tension you would like (how far it travels under full boost) You can adjust the cam plate to give it more pre boost fuel. This will help the bottom end out.

Did you have any spacers in your pump that sat against the diaphragm cap and went over the fuel rod like a ring?
Those can be added if you want to limit the fueling up top.
Click to expand...

Yes, there were 2 small washer like spacers that were there. One fatter one and one really skinny one.

ForealBoreal said:
@asutherland
Hope this all makes sense.
Click to expand...

Mostly. Not certain about the spring tension. Another thing I have noticed since putting the new pin in, is that my boost doesn't build as quickly. I'm thinking my other pin was just far, far more aggressive, resulting in way more fuel. Which means I may need to turn the main fuel screw up?[/quote][/QUOTE]
 
Would the grease on the pin not show where the travel is, look for where the grease has been disturbed when you pull it after a test run?
 
IanB said:
Would the grease on the pin not show where the travel is, look for where the grease has been disturbed when you pull it after a test run?
Click to expand...

There isn't much room between the (full diameter) of the pin and the sleeve walls... most of the grease gets pushed around as soon as you put it in. I'll take it out today and see if I can see any marks on the cut area.
 
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