If you are a 1st gen Cummins owner (’89-’93) and your rig is stock you have probably noticed your rig is less than “fast”, and has a limited top end. You can bury your foot and get up to the speed limit...but the truck just doesn’t seem to have any more legs. If so, be reassured your good ole’ Dodge isn’t broken – it is de-tuned intentionally, from the factory. There are several upgrades, but one of the least expensive tricks (less than $20 bucks!) is to install a ‘366’ spring inside the VE44 injection pump. The net effect is more fuel across the rpm curve for a given throttle input. It will not decrease your fuel mileage but rather give you more ‘pedal’ available for passing and, of course, acceleration, and, more top end rpm potential which in turn means higher cruising speeds. Your Cummins only needs ‘x’ amount of fuel to maintain speed, and most reasonable fuel mods to the pump (including the 366 spring) will only affect mileage under acceleration or heavy load pulling, and that is all up to the driver. IOW, your right foot will affect mileage more than anything else.
There are a few bits of voodoo required to make this work nice and smooth and I'll go into those. Let me know if there are any questions.
First off, digging into a VE44 mechanical injection pump is very similar to working on a carburator - just nuts and bolts and a few small items that like to disappear. I recommend reading through this whole writeup so you'll know where the voodoo is and can be prepared for it. Bottom line - if it's written in red, it's extremely important.
Here is a less-than-great pic of what the pump looks like without the TPS (throttle position sensor - a feature on auto-equipped trucks) and also what a 5-speed rig looks like as-is
Remove the big bolt that secures the throttle levers (one atop the other). Remove the bolt...but not the levers - there are little index marks on the lower lever that you'll need to match up with the slot on the tip of the throttle shaft
. Unfortunately mine would not come apart easily, so I had to yank it all off and guess at the index. This causes a potential problem later on with having the throttle shaft off key with the governor which can cause the engine either to not restart...or to have 'runaway' - uncontrollable fuel. The only way to stop runaway is to slap a piece of wood in front of the turbo and shut down the airflow. This happened once to me and the wood worked percectly. In this pic I also have the AFC cover off to inspect the fuel pin and diaphram...but that's another mod
). Anyway, here's the bolt/lever assy:
The throttle shaft with all hardware removed -
...the hardware, left-to-right in order of disassembly -
You have to remove the AFC boost tube...
...and the 17mm bolt securing the return line -
There are 4 allen bolts holding the top of the pump to the bottom. Remove those (the upper rear bolt can be impeeded by the idle screw - more later on how to alleviate that little problem)
With the top popped loose you'll lose some fuel (much like pulling off a Holley float bowl). Lift the top half up a bit...and you'll be looking at this -
Note the arrows. Lower arrow is the 'top hat' assembly with the governor spring hooked into it. Right arrow is the end of the full fuel screw. Upper is the throttle shaft arm with the governor spring attatched. Use some needle nose pliers and unhook the spring at the throttle arm. It takes a bit of patience - not brute force.
some detailed pics of the smaller stuff -
of note, the red pointer is aiming at the back side of the full fuel lever - this lever can't be moved out of the way during reassembly, which is why the fuel screw has to be removed to put the top back on. The yellow pointer is the fuel shut-off solenoid, FYI.
Full fuel screw. This has to be removed in order for the top to go back on. Screw it back in 1 full turn 'in' past where it came out. This will yield a nice power increase.
Before installing the 366 spring, do a little voodoo. Remember the screw on the back side of the pump...the one in the way of getting that 4th allen bolt out (back side of the pump, behind the full-fuel screw)....yeah let's take care of that. This screw is the idle screw. Remove the idle screw - Note the end with the screwdriver slot
. This screw is a real beyotch to adjust from the back, so, install it from the front
- brilliant! But, while it's out, hack off 1/2 inch or so - not the end with the slot
, and thread it back in from the front to be where it was originally. Hack off enough to clear the 4th allen bolt so when you reassemble the pump you can actually get the allen wrench in there
Now, let's hook it all back together. Getting the spring reattached is a bit tricky. My solution is to carefully remove the throttle shaft from the top of the pump, attach the spring, re-insert the shaft, and then bolt it back on. Lube the shaft with either fresh diesel fuel or any kind of good oil (I use my air gun oil mix - 1-part Mobil 1 10W30, 1-part Marvel Mystery Oil).
Inspect the big rubber seal in the top half of the pump - if it's cracked or looks real bad, replace it. Same goes for the fuel screw and throttle shaft o-rings. With the throttle shaft back in (spring attached), and full-fuel screw removed, pop the top back on, insert the 4 allen bolts, snug good and tight. Screw the fuel screw back in - use a 6mm 1/4" shorty socket - works great. Reinstall the 17mm return line and bolt.
Now, here's more voodoo. The throttle lever rotates counter-clockwise making just the slightest pull against the governor spring. Rotate the shaft CC, and re-index your throttle lever hardware where it was when you removed it. The little slot atop the throttle shaft will index to the marks on top of the lower throttle lever. If it's off by just one index slot, the engine will either barely start/run (if at all) or it'll try to runaway (idle speed will shoot up and try to keep climbing). No biggie, but if you're not sure of the index marks you'll want to have someone start the rig for you while you wait at the turbo inlet with a piece of clean wood to shut off the 'air' - this will kill the engine. I know - it happened to me
That's about it. If you adjusted the full-fuel screw you may have to adjust the idle speed a bit to get it back down. Adjusting the VE44 is very similar to adjusting a carb - one of the reasons I really like these old VE44's.