The Official 1HD-T/FT Fuel Pump Mod Tuning Thread (15 Viewers)

[rebuilt80]

I would like to run it up on a dyno of course, just for consistancy. I've got no need for bragging numbers, but to be able to repeatedly replicate the same conditions and make small but regular changes would be so nice!! The authorities that rule our freeways must sure be getting sick of me pulling on and off it...!

I'm sure both sides of the pond can agree that the end result is the main thing, and how you go about getting there is your own business..?!

My intention was to set max fuel at max point of the pin, which got a bit ugly at the time, but I'm pretty sure I roughly got the pin to fit full travel when I was setting max fuel. But you're right, I have a current test drive that I've got a couple of points of reference on, so I can check it. Been a bit busy but trying to get it done via measuremnet but as you can see, I kind of shot myself in the foot a while back (pre Gturbo) when I was trying to get more fuel in low down. I've ground the off boost flat even shorter, so to get the follower to sit on the off boost flat, I've got to lift the pin even higher, which means more spring tension to get it to start to move. Which doesn't help me getting off the line.

But setting the smoke whilst having the trailer on means it pretty clean without it.

I've always reckoned the med range is a bit doughy and lean tho. What do people thing about grinding in a slight concave to get some more fuel going thru the midrange?

 

[rebuilt80]

Been busily winding down the spring tension to get some more punch into it, and getting happier with results. Still tuning with the trailer on, so its a bit different without the trailer, but I guess its a daily so it needs to be safe towing.

Will head up some larger hills over the weekend, might see if I can sneak a shim in for the top end, and get a little more main fuel flowing, keeping the top end under control...

 

[jvoelcker]

Have any of you had any issues with tuning with pusher pumps fitted?

I have been playing with two '94 80s with 1HD-Ts, both have the same exhausts, charge cooler and Bad Boy turbos and I was noticing that one was producing more grunt at higher revs than the other.

The one with less grunt was fitted with a Walbro pusher pump a few years back in a bid to help with fuel supply at higher revs, however this seems to be causing the problem especially since the pump has recently been recalibrated.

Chatting to pumps specialist it seems like the fact that the Walbro is supplying fuel at a constant 10psi it is affecting the transfer pressure leading to the timing being more advanced at higher revs - does that make sense?

Unplugging the Walbro immediately provides a lot more grunt through the rev range.

Someone has suggested that it may be possible to tweak the pump so that it has the benefit of the pusher pump without the causing the advanced timing problem.

Has anyone else encountered this?

 

[CycloSteve]

IIRC the 1FZ-FE in-tank fuel pump uses a resistor and runs 6v at low loads, and then ramps up to 12v at higher loads. I am not sure if this is mapped purely to RPM, or another item which the ECU determines load. With the diesel, perhaps you can use a MAP (Manifold Absolute Pressure) sensor with a resistor circuit to control the amount of voltage which is supplied to your Walbro pump. It may be a hair-brained idea, but definitely would lower the amount of fuel that the pusher pump supplied on the low-end, and only supply higher pressures when under boost.

My only question is why leave the Walbro connected if there is better grunt throughout the range without? Have you run an O2 sensor in the exhaust to see if there is indeed a need for the extra fuel due to the truck leaning-out at high load / RPM?

 

[ForealBoreal]

You don't need a pusher pump with the VE pump. Rip it off. There is no benefit, people say it's effortless to prime the filter but that's what the filter primer is for....

 

[arnott1t]

You don't need a pusher pump with the VE pump. Rip it off. There is no benefit, people say it's effortless to prime the filter but that's what the filter primer is for....

A lot of the cummins ve pumps are pusher fed and in fact it was good practice to upgrade. Not sure they are different inside but I believe them to be the same.

 

[jvoelcker]

You don't need a pusher pump with the VE pump. Rip it off. There is no benefit, people say it's effortless to prime the filter but that's what the filter primer is for....

The pump wasn't on there for priming, it was there to help with the older worn pumps where the lifter pumps are worn - I've seen them transform the performance on some trucks.

 

[ForealBoreal]

well keep screwing with it if you think its helping.
Best to start with bypassing that pump and if it alleviates the problem.
if not your back to square one. Doesn't take a rocket scientist to figure that out.

 

[jvoelcker]

IIRC the 1FZ-FE in-tank fuel pump uses a resistor and runs 6v at low loads, and then ramps up to 12v at higher loads. I am not sure if this is mapped purely to RPM, or another item which the ECU determines load. With the diesel, perhaps you can use a MAP (Manifold Absolute Pressure) sensor with a resistor circuit to control the amount of voltage which is supplied to your Walbro pump. It may be a hair-brained idea, but definitely would lower the amount of fuel that the pusher pump supplied on the low-end, and only supply higher pressures when under boost.

An interesting idea, but I suspect re-callibrating the timer side of the pump for operation with the pusher pump may be an easier option.

My only question is why leave the Walbro connected if there is better grunt throughout the range without? Have you run an O2 sensor in the exhaust to see if there is indeed a need for the extra fuel due to the truck leaning-out at high load / RPM?

It's plumbed in, but not connected up at the moment, but yes now the pump has been recallibrated it will be good to check to see if the pump is actually needed now.

Over Xmas I'm installing an all in one display and data logger to fit to the truck that will track all key aspects like EGT, AFR, Oil Temp, Water Temp, Oil Pressure, Pre and Post charge cooler temps, Auto box temp, etc. A great toy we are playing with, but once installed I'll start the tuning in earnest

 

[ForealBoreal]

Fitted the dark coloured one in the centre. Tuned it to the stiffest spring I had, works well.

Order left to right
Cummins 6bt, cummins 6bt, industrial 6bt, Land Rover boost pin, stock denso pin, one that came in the xxi pump.

Note the pumps sleeve was changed to fit a different sized fuel pin. I wanted more options.

 

[SeaJay]

Do you need to be towing something heavy uphill to set the boost comp spring tension properly? or is it ok to set not towing if you don't regularly tow? I have a 1HDFT with a Gturbo BB 26psi, XXI air box, cross country top mount and 3 inch exhaust. I have the star wheel set 50 clicks up from fully wound down. Sits on 35 to 45 AFR at 6psi 100kmh, and drops to around 21ish AFR if I floor it at that speed. Am I correct in thinking that as long as it leans back out its ok at that?

 

[ForealBoreal]

That sounds ok. Full load sounds fine. What is your low end AFR off the line?

 

[SeaJay]

in the 22 to 24 range, I would have to do some WOT starts to be sure though. Pulls hard off the line, no black smoke

 

[ForealBoreal]

Starting AFR is usually 16.5 or 17:1 then leans out to your 21:1

 

[ForealBoreal]

If you want it richer off the line play with the cam plate at the top a little bit

 

[SeaJay]

do you mean the adjustment on top of the compensator?

 

[ForealBoreal]

Yes, so what that does it adjusts preboost fueling
It essentially pushes the pin in deeper without really modifying your spring tension

 

[SeaJay]

thanks, Ill have a good look at what its doing off the line and adjust it there if necessary

 

[SeaJay]

I didn't touch the cam plate, but wound the star wheel down 8 clicks (42 from bottom), it does drop into the 16's briefly, maybe a second, then 20.6 to 21.8 or so for a standing start holding WOT. Is there a magic number it should lean back out to at 100kph to retain some economy? it settles on 36 to 42 at 6psi on flat road at that speed.

 

[ForealBoreal]

I don't know what it should be at cruise. What else are people running?