89-93 12V Cummins Tech Talk '89-'93 5.9L 12 Valve Cummins VE Engine Tech Articles

Getting Full Throttle Out of Your VE Pump

 
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  #1  
Old 01-03-2009, 10:27 AM
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Default Getting Full Throttle Out of Your VE Pump

It seems odd to me (and almost anyone else) that you don't have full throttle swing on most of the VE pumps straight from the factory. So after a day of sipping on my favorite beverage and staring at my grinder I said... Why not!

So hang on as we try not to tear up the throttle linkage on my pump all in the search for more fuel!

I'm gonna start by saying this is not for the weak at heart... At all... You will be grinding on part of the pump and you wont be able to go back without buying new parts!

After cranking in my full power screw to the verge of runaway when you would snap the throttle it would hang there for a while before slowly coming down and the idle was about 1000 RPMS with the spring removed. It needs to idle warm at around 750-800.


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I started by taking off the throttle linkage by removing the nut circled in green. After you take the top piece of the throttle linkage off you need to look at the how the bottom piece is attached to the shaft. You will see that it has a star shaped hole in it that indexes it to the throttle shaft. Note the position. Now take it off and rotate it one notch clockwise, Then grind off the tabs circled in red, teh make contact with the fuel line circled in blue before you get full travel. Then reassemble everything, put your return spring back on the linkage and start it up. Chances are you idle is gonna be REAL high! my truck idled about 2300 RPM

This is the point of no return. Take the linkage back off and go get your grinder and start cutting!

You need to start removing material
A LITTLE AT A TIME!!! THIS IS NOW YOUR IDLE ADJUSTMENT!!!

The linkage will make contact with the pump housing and that is your new idle adjustment. I cant say this enough. You can remove material (lower idle) but you cant put it back!!! After taking off a little put it back on and start the truck to check the idle. Keep repeating this till it gets down to that 750-800 mark

Here is about what I had to take off. The red line to the right shows were it was. The red line to the left is the tab we ground off earlier.
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Here is how the linkage sits against the pump.
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After you get the idle were it is you will notice a few things. First there will not be enough swing with the throttle pedal to achieve full throttle. All you need to do to fix this is swap the return spring and the linkage adjustment were they attach to the linkage. So the adjustment rod goes in the hole closest to the pump (just use two wrench's to remove it) and the spring goes in the hole farthest from he pump. Look at the first picture in this thread and the third to see the difference. Next when you go to hook the throttle linkage adjustment back up you might notice that it is to short. You need to loosen the jam nuts and rotate the shaft to lengthen it. Then remember how I was telling you that the throttle would hang for a few seconds before slowly coming down? No longer. You snap the throttle and it returns to idle right away! DO NOT SNAP THE THROTTLE WHEN THE IDLE IS HIGH!!!

Thats it! Get in and enjoy your new found fuel. I picked up a solid 3-4psi of boost and can drag my fuel pressure down to 0psi now with about half throttle. Before it would only get down to about 3psi at WOT. There is ALOT more smoke but it is easy to control. Also you will note the throttle is alot touchier.

ENJOY!!
 

Last edited by RSWORDS; 01-03-2009 at 02:39 PM.
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  #2  
Old 01-05-2009, 07:28 PM
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Good write up Bobby.
 
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Old 03-02-2009, 09:43 PM
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I thought switching the throttle linkage and the spring gave you full sweep of the throttle arm. What does all this grinding do compared to just swapping the spring and linkage?
 
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Old 03-04-2009, 09:03 AM
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Originally Posted by Kebo
I thought switching the throttle linkage and the spring gave you full sweep of the throttle arm. What does all this grinding do compared to just swapping the spring and linkage?
if youpay close attention when you are messing with the linkage you will notice that it will hit the fuel line. Grinding the arm alittle will give it some more travel before it hit. Your clearancing it. If you take the arm off and clock it one tooth you will get even more travel and fuel. but it is gonna idle REAL high. That is when you need to start grinding on the idle stop to get the idle down.
 
  #5  
Old 03-11-2009, 03:03 AM
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heck it helps most trucks just to remove the throttle stop (piece of allthread that threads through 2 ears on the pump but has no use what so ever)......i took mine out and that made a world of difference, i also removed my entire idle screw and just let the linkage rest against the housing but if i would of went a step further and done all this im sure it would of helped immensely.....my truck also idled a little high cause of not doing this mod and let me tell you with no power brakes (vaccum system needs work) that plays hell in traffic on your right foot.....
 
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Old 03-11-2009, 05:21 AM
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Reckon i can get the truck in the shop and do this without the wife findin out? she kinda cringes when i get powertools out to work on "her" truck.
 
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Old 03-11-2009, 06:57 AM
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Originally Posted by txredman
Reckon i can get the truck in the shop and do this without the wife findin out? she kinda cringes when i get powertools out to work on "her" truck.


Good write up. Very interesting. So it does make quite a bit of difference Faint of heart, never been one of those either
 
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Old 03-11-2009, 07:05 AM
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Originally Posted by txredman
Reckon i can get the truck in the shop and do this without the wife findin out? she kinda cringes when i get powertools out to work on "her" truck.
Sure You Can!
 
  #9  
Old 04-27-2009, 02:50 PM
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Bobby, after you grind off the back piece that hits the idle screw do you still have an idle adjustment is does that no longer exist and your stuck with what you've got. The reason I ask is the last time I tweaked my full power screw I had a lil bit of a high idle and needed to adjust it
 
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Old 04-28-2009, 07:57 PM
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You can lower the idle by grinding more off, if yuo want to raise the idle... Well break out the welder!

Also jason as Logan said above remove teh high idle screw (looks just like the idle screw except on drivers side of the pump. Just take it out and toss it in the garbage!
 


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