When we bought our '89 Dodge, we found out during the long drive home that it had a top speed of about 75 mph. The horsepower was there, just not the rpms. When we put the truck on the dyno, our problem became even more obvious as we noticed our truck was pulling back fuel to the point where we only had about 50 horsepower at 80 mph. It was no wonder our truck felt so slow at highway speeds.
Since we were first timers on this modification, we had Troy Chambers of J&H Performance walk us through the install. The first part of the governor spring installation involves removing the throttle linkage. Note the marks on the linkage so you can put everything back where you started once the spring is installed.
Interestingly enough, the solution to this limitation cost only $15.00. The Bosch VE injection pumps use a small spring (called a governor spring) that limits the fueling as revs rise, ultimately stopping at about 2,700 rpm. The solution is as simple as replacing the factory spring with a 3,200-rpm or 4,200-rpm governor spring, both available from many aftermarket sources. We went with the 3,200-rpm spring, as the 4,200-rpm spring can cause valve float unless you upgrade the stock valvesprings.
Since our truck came with a non-overdrive Torqueflite 727, we really needed the extra 500 rpm that this spring would give us. After we turned up the pump, our truck would top out at about 85 mph. The 3,200-rpm spring gave us a new theoretical top speed of about 97 mph, which meant we could now run it down the dragstrip! After the spring was installed, we took a few impromptu blasts down the highway, and verified that we had full fueling now up to about 75 mph before it would start to taper off. Before, even though we could go about 85 mph, it would start pulling fuel back at about 65 mph.
Next, the main throttle return spring must be removed. Be careful, as this part is plastic and can break if you try and force it. Wiggling it loose is the preferred removal method. | 
With the linkage off, the top of the pump can be removed. Make sure you unscrew all of the Allen bolts that hold the pump head in place because there are a couple toward the back of the pump that are a little hard to see. | 
With the screws removed, the pump can now be carefully lifted off. Note the governor spring (arrow). |