How to turn up aMack DM690 with a EM6

Highfinance97

Highfinance97

Garofalo Enterprises
Joined
Jul 30, 2006
Messages
5,135
My buddy has a 1987 Mack Dm690 with a EM6

How do we add fuel??

Its got a plate in it kind of like my adj. one from sheids

but it looks like this one has an up and down adj. :poke:
Mack fuel adjustment.jpg
 
It should have a silver can on the front of the pump. Unscrew it and add some shims that will help you bottom end fueling.
 
You ever get more fuel out of it.? They are pretty easy to do. What pump is on it? Ambac or United Tech. or Robert Bosch?
 
BGarofalo said:
You ever get more fuel out of it.? They are pretty easy to do. What pump is on it? Ambac or United Tech. or Robert Bosch?
Click to expand...

Ill let you know...idk much about the big trucks.....

he got some power but i dont think much

any tips Brian?
 
Yea I can tell you how but it is differant for differant pumps. I need to know which one is on his engine. I just did a pump on an mid 80's e6. Here is a few pics of the United Technologies pump. This info should interchange with the American Bosch pump. The Robert bosch is differant.

The two pumps im talking about here will have a 6 bolt cover on the govenor housing at the top. Remove the cover. One bolt is sealed with an aluminum cap witch can be removed by striking the center with a punch and using a screw driver to pry out. There is a 24 point bolt under it that needs to be removed. Your local pump shop should have the socket needed.

After you remove the cover you will find the govenor lever and a cam plate. The stop bolt for the cam plate is what you are going to adjust. It has a jamb nut that needs to be loosened and then back out the bolt about half a turn. A full turn is pretty much the limit. Its up to you to see where you like it. Then tighten up the jamb nut and re-assemble. Mark the original location of the cam plate assembly for future referance if you wanna bring it back to stock. Pyrometer recomended!

Plug off the air line going to the puff limiter on the front of the pump too for added low end fuel. Or unscrew it and add a washer to it.
 

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I used to work at a Mack/KW dealer and we had guys come in and want the buttons and springs for the Cummins motors. I got told we can get sued for turning up big trucks if they get in a wreck. The parts guys at Cummins told me the same thing. Those guys would get straight up pissed off, if they thought you were mixing parts to get more power. It was weird... but something to consider anyway.
 
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