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Roscoetaggart

1983 Mack E6 350 injector pump issues.

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Hi there, 

I have a 1983 R688 with the E6 350 motor in it, motor has had top and bottom end rebuild 5 years ago and runs very well but a couple of days ago it wouldn't fire up up me.

It turned over on me fine but it was as though fuel wasnt getting to the I injectors. I started the fuel bleeding process (which is a hell of a job when the truck is air start and you have a small compressor) and I wasnt able to get fuel past the injector pump. I got to the point where I cracked off all the fuel lines heading to the injectors and when I try and prime or crank the motor, the pump doesnt send anything out the top. 

My guess is that I havent bled it properly, but am well aware these pumps were not renowned for their reliability. Any help would be appreciated.

-plenty of fuel at the injector pump from the tank

-engine cranks and will run on ether or brake clean briefly so I presume timing drive is fine

-Fuel shut off seems to be in the right place (i think)

Pics of the injector pump attached if someone could let me know more about the pump as it has been painted over so the tag on it is near impossible to read.

Cheers.

-

15598586812614374733074064999965.jpg

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Check the rack to see its not stuck in no fuel postion

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Posted (edited)

Don’t mess with a lot of engine rolling.

Make sure filters are still full. Crack a line on output side of lift pump. Place a plastic garbage bag on tank opening with hands sealing bag to opening. Stick air nozzle in and pressure fuel through pump and fasten line while your flowing fuel. Should be able to operate the hand primer for rest of operation. Crack fuel overflow valve and turn engine over to confirm system has flow. Crack all lines and position throttle full fuel, make sure shutoff is positioned for run and crank. Should be fuel, otherwise Theakerstwo scenario may be playing out. 

Edited by Mack Technician

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Is the stopper off properly?

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You "think" fuel shutoff is in the right position, try it in the "other" position and see what happens. Looks like a weird setup with that chain hanging on the shutoff lever....

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I have checked the fuel shut off again and it is spring loaded in what I would assume is the 'open' position, with an air ram to shut it off. I'll take the spring off and try it in the other position and let you know the results, thanks guys

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check the buttons & springs in the transfer pump

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Posted (edited)

pull the plate off of the side of the pump housing as you turn engine over watch what happens.

Edited by theakerstwo

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Do something!

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Sorry for the late reply guys, turns out the little air ram that actuated the fuel shut off was jammed and have ended up having to replace it. The way I worked it out was I disconnected everything from the fuel cut mechanism and when I put it in the right place the truck started fine and narrowed it down. Thanks for your help on this.

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