VE Pump tweaks, still looking for more power.

[Turbo67]

I would appreciate those of you experienced with the VE Pump to give this some thought and recommendations.

I’ve been trying some mods on my 93 Cummins with a VE pump. Bought the Truck about a month ago.
It’s a 2500 5 speed, extended cab, long bed.

When I bought this truck the power band was 1700 to 2100 rpm. I could get it to go to 2500, but not really any power after 2100. It ran fine, got around 24 mpg on a 250 mile trip at 65 mph with the AC blowing cold, just very narrow power band.

Installed a fuel pressure gauge after the fuel filter and an intake manifold pressure gage to monitor things.
I saw a max of 16 psi of boost in 4th gear WOT.
Truck makes 5 psi of fuel pressure back then and now after all the below changes.

Indexed the throttle shaft one notch, This was the single most eventful thing done. Truck will now make 21 psi boost in 4th gear, pull to 2800 rpm and rev on up to 3000 rpm. Much more driveable with the extended rpm range.

Next tried indexing the aneroid fuel pin to the richest setting, maybe a little more power, hard to tell. No smoke at all.

Moved the star wheel under the aneroid down to its lowest setting, no difference in power. It was within 3/4 turns of bottoming out when I removed the top and is now fully bottomed. No change in power.

Next turned main fuel screw in 1 turn. This raised the idle speed, and I had to lengthen the control rod by 3 turns to back down the idle speed. No change in power. Maybe a little smoke at lower rpms and WOT.
Turned the main fuel screw in ½ turn more (this produced a slow return to idle speed) so I backed it off ¼ turn. This does now produce some smoke at low rpm and WOT. Hard to say if it makes any more power, but maybe slightly more. It does now smoke when rolling into the throttle from slow speeds in 2nd or 3rd.

Next adjusted the high speed throttle stop screw and moved the linkage pin to the inside hole and the return springs to the outside hole to get more travel out of the throttle. This made a noticeable difference in power, boost and smoke. It will now achieve 23 psi in 4th gear at WOT. Smokes rolling into the throttle from slow speeds in 2nd or 3rd.
(I got more out of the 2 throttle indexing / throttle travel changes than any other thing I have done so far)

Started backing off the aneroid set screw to try to reduce the roll into the throttle smoke. ¼ turn increments at a time, at 2-1/4 turns leaner, it made a little more power. But ½ turn more leaner the power dropped. So I turned it back down ½ turn, power did not return. Cannot seem to find this lost power. I tried more turns in each direction, but don’t seem to feel it anymore. It does still smoke when rolling into the throttle at low rpm.

Checked the timing, at TDC, I have .046 inches plunger lift, this is very close to the correct setting of 1.25 MM, (.049).

Installed the 4200 rpm governor spring and clipped two coils from it. Clipped, it is essentially the same static length as the stock spring.
No change at all in power level. I have not, don’t plan to rev it over 3000 rpm, (stock valve springs) but it hits peak torque still around 2500/2800, so no reason to anyway. It is more responsive to small throttle inputs, but does not make any more torque than the stock spring.

Changed the fuel filter, same 5 psi fuel pressure downstream of the filter, at idle or WOT as with the old filter.

Tried it with the KSB connected and disconnected. I cannot tell any difference. I did bench test the solenoid on the KSB, when 12 volts is applied, the solenoid does move the plunger out to close the hydraulic circuit. I have read that depending on the year of the engine, when power is applied to this valve the results can be opposite.

Roll into the throttle in 2nd or 3rd gear does not break loose the tires. They are dried out old radials.
Don’t get me wrong here, the truck runs night and day better than the day I drove it home last month. But I was expecting lots more torque with these tweaks.

***What am I missing?***
I really expected a roll into the throttle to break loose the tires….am I expecting too much?

What else can I try to boost torque for no cash outlay?

Is it time to consider spending small amounts of money for the next attempts at increasing torque?

[RCCUMMINS89]

An aftermarket fuel pin will give you some more power. AFC settings won't change power (starwheel adjustment).

Indexing throttle shaft shouldn't of been needed.............where is it at now? With the shortened 4200?

An incorrect throttle indexing can affect how much you can turn the pump up.

The fuel screw (if never been adjusted before) can be turned in a lot more than an idle hang, unless something is funky.

To help with a starting point.....I've never tweaked a ve pump that couldn't make at least 30 psi with power screw adjustments on a factory turbo.

[oldestof11]

Turbo, where do you live?

[Turbo67]

An aftermarket fuel pin will give you some more power. AFC settings won't change power (starwheel adjustment).

Indexing throttle shaft shouldn't of been needed.............where is it at now? With the shortened 4200?

An incorrect throttle indexing can affect how much you can turn the pump up.

The fuel screw (if never been adjusted before) can be turned in a lot more than an idle hang, unless something is funky.

To help with a starting point.....I've never tweaked a ve pump that couldn't make at least 30 psi with power screw adjustments on a factory turbo.

Thanks for replying.
***Throttle shaft is still indexed 1 spline with the shortened 4200 spring.***

***I turned the fuel screw in a total of 1-1/4 turns. Any more than that would slowly return to idle. I had the board ready, and turbo open, but did not have to use the board.

I don't understand your statement that the fuel screw can be turned in a lot more than an idle hang...will it not get into a run-away if I turn it in more?

Please explain in more detail how the throttle indexing can affect how much the pump can be turned up. I have it indexed where it pulls more on the governor spring, as if all the "slack" is taken out. Indexed in the same direction it turns when pressing on the accelerator pedal.

[Turbo67]

Turbo, where do you live?

North Alabama, where are you oldestof11?

[oldestof11]

IL.

You are just using terms like aneroid and plunger lift, things that are most commonly said by someone overseas.

[Turbo67]

I am new to the Cummins, only been at it for a month. Been working on an old Mercedes diesel for the past 5 years, so I probably picked up some terms there.

[Remps]

Did you remove the nylon washer from the fuel pin? Grinding the stock pin only takes a few minutes and can provide the same max fuel as an aftermarket pin. Make sure the horizontal pin that rides against the fuel pin is lubed and moves freely. Put a little grease on the fuel pin so you can tell if its getting full travel.

[Turbo67]

Did you remove the nylon washer from the fuel pin? Grinding the stock pin only takes a few minutes and can provide the same max fuel as an aftermarket pin. Make sure the horizontal pin that rides against the fuel pin is lubed and moves freely. Put a little grease on the fuel pin so you can tell if its getting full travel.

Ok, I will remove the nylon washer, grease the horizontal pin and fuel pin and report back.
Thanks for the input.

[RCCUMMINS89]

If you remove the nylon washer from below the stock fuel pin, you can actually push down and bend the slide pin. To run it properly with the stock pin, it has to be ground down and checked until correct.

[Turbo67]

Did you remove the nylon washer from the fuel pin? Grinding the stock pin only takes a few minutes and can provide the same max fuel as an aftermarket pin. Make sure the horizontal pin that rides against the fuel pin is lubed and moves freely. Put a little grease on the fuel pin so you can tell if its getting full travel.

Ok, I will remove the nylon washer, grease the horizontal pin and fuel pin and report back.
Thanks for the input.

I removed the fuel pin and inspected the rub mark, it goes to within about 1/8 of an inch of the smallest part of the fuel pin. Then greased it as well as the shaft and horizontal pin. Horizontal pin moves freely, but greased it anyway. Removed the nylon washer. Then took it down the road. No increase in power. Removed the pin and inspected the new rub mark. It is longer and goes right down to the smallest point of the pin, so the tweak of removing the washer does let my pin extend further down into the bore and correspondingly is letting the horizontal pin move further toward the rear of the vehicle. Sadly, no increase in power for me.

I did take note of my boost gauge during this and noticed it was only going to 21 psi, where last week I was seeing 23 psi and some more power at that time. I do not believe this loss of boost is related to removing the nylon washer, rather I believe this has been the case for the last week, I only just thought to watch it as I ran through the gears today.

Removed the inlet hose to the turbo and disconnected the pressure line to the wastegate. Still only have 21 psi in 4th gear at WOT. Less in 5th gear, but at a lower rpm to remain a relatively safe driving speed.

I suspect something is not allowing enough fuel flow, hence the 21 psi rather than higher psi.

Thoughts anyone?

[RCCUMMINS89]

It will allow it to go further down......double check your marks though. I've heard of some being right to the deepest point, but almost all (if not all) that I've looked at and tested in person, go further....and the the broad part of the fuel pin actually hit the slide pin on the side.

Point is.... make sure it isn't.

[Turbo67]

It will allow it to go further down......double check your marks though. I've heard of some being right to the deepest point, but almost all (if not all) that I've looked at and tested in person, go further....and the the broad part of the fuel pin actually hit the slide pin on the side.

Point is.... make sure it isn't.

Thanks for the detailed description that helps me visualize the concerns. I will pull it out and check it carefully and the slide pin.

In your earlier reply you commented on my throttle indexing and main fuel screw tweaks.
I would appreciate your educating me more..

Thanks!

[RCCUMMINS89]

They are both connected to the same lever, ultimately.

Essentially your power screw is a starting point for your throttle (indexing controls throttle position). Increase indexing, fuel screw has to be backed off.........which gives more tension on gov spring, but less overall fueling. Opposite is opposite.

[Turbo67]

Ok, I think I am beginning to understand: So I should put the throttle indexing back to stock, then turn in the fuel screw more.

Is there anything gained by indexing the throttle even more in the opposite direction and turning the fuel screw in more still?

Still don't understand your earlier comment that the fuel screw can be turned in more than a throttle hang. Is your term "throttle hang" what I am calling a slow return to idle?
Is a slow return to idle safe, or is it at the point of approaching a run-away?

Thanks for the clarifications!