1hd-t vs 1hd-ft injector pump

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franzugan

franzugan

10 Year
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Apr 20, 2011
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Uganda
Hi guys, simple question that I cannot find an answer for. I have the 1hd-t engine in my car and have an ft pump sitting in the garage shelf. It needs to be taken to the shop and tuned back to specs.
My question is: are there any differences between the two, can they be interchanged and if yes what would likely be the difference.
Cheers!
 
The FT pump had design improvements over the 1HD-T, I could go into details but the short story is it should idle/preform smoother. Fuel output is higher, cant tell you off the top of my head but its in the range of 15%. Advance curve is similar. You definitely could bolt it straight on and use it providing the throttle linkage suits. If your interested in know exact differences post both pump numbers.
 
I was under the impression the FT pump ran at a higher pressure?
You could still use but need the FT injectors as well. Unless you can reset the original ones to the higher spec.

Or i could be talking out my bum and thinking of the FTE which is totally different.
 
The FTE definitely will generate a higher peak pressure. It's a radial piston design which is stronger and generates a faster rate of injection. FT does have a slightly more aggressive cam and longer stroke which is an advantage in trying to create a higher peak pressure. It would still run fine with the 1HD-T standard injectors, opening pressure wont effect the pumps ability to operation (well it actually can change overall quantity delivered but I wont get too deep into that :)) and the pressures between the two injectors are pretty similar anyway.
 
Anthony tanks a lot! One other question, since I have no clue about IP. If I get it to the shop do I need to tell the guy anything in order for it to be tuned like the one I already have? All I know so far is that I'm running about 14psi of boost.
My car is at the shop right now, getting dome manifolds for IC fabricated so cant get IP numbers. Only have the FT numbers with me.
Cheers
 
Ok first off if your FT pumps being sitting round for a while there is a chance internal parts could be gummed up. This happens with diesel when it sits for long periods of time.

As for the FT vs 1HD-T the most noticeable difference is at between 1200-1800 pump rpm (2400-3600 engine) where fuel increases 20%. This can't be tuned out, it's how the pump has be designed to work but as long as your EGT's stay within check it's going to pull a lot better. As for timing 1hdt stock is 1.18-1.24 @ tdc. The ft has two. Warm climate 1.37-1.43 or cool 1.52-1.58mm @ tdc. Being that I've never fitted an FT to 1HD-T I'd imagine it'll be timed somewhere between 1.37-1.58mm.
 
If the EGT's got too high top end you could try turning full load screw down and up on the unboosted screw. The 20% is progressive so midway it's about 10%. Someone else here might know what the stock 1HD-T egts are how room there is to move up top.
 
@Antony are you able to comment on the effects of injection pump timing on cold starting, EGT's, fuel economy, and performance? I'm still a bit fuzzy on how these all fit together.
 
Antony said:
As for the FT vs 1HD-T the most noticeable difference is at between 1200-1800 pump rpm (2400-3600 engine) where fuel increases 20%. This can't be tuned out, it's how the pump has be designed to work but as long as your EGT's stay within check it's going to pull a lot better.
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Very interesting. All the good fuel shops (and Unfort I found this out after the fact) recommend building the D-T pump to the FT specs. There is apparently a Denso bulletin regarding this and it helps remove roughness. You don't need to mod the D-T injectors, but if they are due for overhaul they can be matched also via the same Denso bulletin.

My pump now has this mod. I did not know about the 20% fuel increase, but this explains why I see AFRs go south and EGTs rise after 2400rpm. There is power in this zone, but I find EGTs too high especially on the 12v early combustion chamber. The later 1HD-T might handle it a bit better.

I have asked many people about fuel delivery over rpm and been told it did not change. The AFRs show this clearly and I have been chasing my tail trying to solve it.

In my humble opinion, on a non intercooled engine at standard boost, there is not a lot of room to move up top and you will need to be conscious of managing it.
 
Glad your getting to the bottom of this and its all making sense.

Looks like you need an intercooler and some more boost:clap:
 
IanB said:
@Antony are you able to comment on the effects of injection pump timing on cold starting, EGT's, fuel economy, and performance? I'm still a bit fuzzy on how these all fit together.
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Ian I'll tell what I know, hopefully it answers your question.

Most systems be it mechanical or electronic will advance the timing on a cold start up under till warm at idle. The major advantage of doing this is keeps the engine burning clean, no or minimal white smoke.

I would expect to see higher EGT's with a advanced engine vs retarded. The further you inject fuel before TDC you are then expecting the engine to work against it and compress somewhat the combustion process taking place. The closer you get to TDC or after the less time the injected fuel has to burn and you get a weaker, cooler combustion. That results in less power, so less preformance.

You'll generally find if your diesel is under preforming and its not a fuel delivery issue you'll drive round, heavy foot and use more diesel.
 
David60series said:
Very interesting. All the good fuel shops (and Unfort I found this out after the fact) recommend building the D-T pump to the FT specs. There is apparently a Denso bulletin regarding this and it helps remove roughness. You don't need to mod the D-T injectors, but if they are due for overhaul they can be matched also via the same Denso bulletin.

My pump now has this mod. I did not know about the 20% fuel increase, but this explains why I see AFRs go south and EGTs rise after 2400rpm. There is power in this zone, but I find EGTs too high especially on the 12v early combustion chamber. The later 1HD-T might handle it a bit better.

I have asked many people about fuel delivery over rpm and been told it did not change. The AFRs show this clearly and I have been chasing my tail trying to solve it.

In my humble opinion, on a non intercooled engine at standard boost, there is not a lot of room to move up top and you will need to be conscious of managing it.
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Well David it does sound like you have been paying attention :-)

Yes there was a mod for an idle hunt in the earlier 1HD-T crusiers. It was limited to few models/pumps and the ones I actually saw with this fault were savage. You weren't able to back a trailer or anything along those lines. The mod was extensive and included pump mod (camplate, fulcrum lever, delivery valves etc it was large) injector pipes and injectors. It was a bulletin either through Denso or Toyota. Now I say actually saw because I know alot of repairs were put in as precaution. It was generally believed that the change from standard delivery valves to constant pressure valves (do a better job of evening out the residual pressure in your injector lines and stopping secondary injection) was the biggest influence in fixing this fault.

Now if they have fitted FT components I'd be surprised if it didn't have that stronger fuel curve. Unboosted is the same. At 1200 pump rpm its 3% higher and by 1800 20%. Advance curve very little difference and high idle is the same. On the plus side you have a better pump for any future engine mods.
 
That is opposite of what i understand Anthony.

Retarded timing causes High EGTs and poor economy as the combustion is almost chasing the piston down and as you say reducing power so the heat is just going out the exhaust. Then you put you foot down more to get better performance and pump in more fuel and raise EGTs more and its a viscous circle.

Correct timing will see good economy and lower EGTs. You can advance the timing slightly to get better performance but it is risky as you get further BTDC because of the reasons Athony said (nailing)

Best to set timing at the manufacturers specs.
 
Imwhere said:
That is opposite of what i understand Anthony.

Retarded timing causes High EGTs and poor economy as the combustion is almost chasing the piston down and as you say reducing power so the heat is just going out the exhaust.
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That's an interesting point and honestly I havn't tried an over advanced engine or retarded and tracked EGT's but I have seen engines (on inline pump applications) with over advanced engines melt pistons and have overheating issues. As well an engine with low compression produces white smoke because of a cool combustion, the same white smoke is produced with retarded timing as the combustion is cooler.
 
Antony said:
Well David it does sound like you have been paying attention :)

Yes there was a mod for an idle hunt in the earlier 1HD-T crusiers. It was limited to few models/pumps and the ones I actually saw with this fault were savage. You weren't able to back a trailer or anything along those lines. The mod was extensive and included pump mod (camplate, fulcrum lever, delivery valves etc it was large) injector pipes and injectors. It was a bulletin either through Denso or Toyota. Now I say actually saw because I know alot of repairs were put in as precaution. It was generally believed that the change from standard delivery valves to constant pressure valves (do a better job of evening out the residual pressure in your injector lines and stopping secondary injection) was the biggest influence in fixing this fault.

Now if they have fitted FT components I'd be surprised if it didn't have that stronger fuel curve. Unboosted is the same. At 1200 pump rpm its 3% higher and by 1800 20%. Advance curve very little difference and high idle is the same. On the plus side you have a better pump for any future engine mods.
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I believe the Denso pump part number for the early ones ends in 7820. I actually never experienced the hunt until it got rebuilt the first time. Apparently this is not uncommon either. I was once told only the Aus versions used this particular pump model to save a few dollars. Unsure if true.

I believe the parts are in the order of $1k to do the mod.
 
All the ones I saw were Jap imports and auto. Actually had one turn up at work a couple of months ago but hadn't see one prior in 10+ years. It's definately not unusual to see a 1HD-T with a slightly unstable idle or very minor hunt and there's been plenty of theroies of why talked about.
 
My pump doesnt hunt or surge but it does idle a lot lower when the truck is facing uphill. apparently it will get worse and requires a rebuild.

I have been told the early 1hd pumps are missing a spring on the governor or something and this reduces fuel delivery. they were added from the factory after 8/92 build date. This is in Australia anyway not sure if ROW has this issue.
 
What changes when you face up hill? Auto or manual? I've not heard of a missing spring before. Every condition in the pump is a balance of spring force vs flyweights (centrifugal) so once your idling at your set speed only load can/will shift it. That sounds unusual!
 
I have found this to be a reasonably common issue on 1HD Toyota engines.
My 96 1HD-FT auto suffers from this issue as well. I believe reading that thee was a spring in the pump somewhere that lost some of its spring rate over time, or something like that.
I believe the solution to this has been posted on here somewhere.
 
Mine is a manual.

Idle gets lower the steeper the hill, i pull the handthrottle a touch to lift it back up. Im told it will get to the point it will stall.
Im not sure, that is what i was told by my local pump builder. Most of the pumps have been rebuilt and had the offending spring added.
I have no other symptoms and runs like a top!
 
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