CV 713 EUP problem

[Aletasman]

I'm working on an 03 cv713 with the AI460 motor. It has a miss and has terrible pickup when accelerating. I have 2 eup's that aren't acting right. If I crack the lines at the pumps, cyl. 2,3,5&6 all have fuel pulsing out of them and the motor changes pretty drastically. When I crack the lines on vylinders 1 and 4, there is a very slight change in idle however the fuel is coming out in a steady stream at kinda low pressure. I have no codes present and I have replaced the nozzles and lines on these 2 cylinders. I have swapped the eup's with other cylinders and the problem is specific to 1&4. I pulled the cam followers and did a visual inspection of the cam lobes and everything is fine there. Today I unhooked the connectors and performed a continuity test with the wiring as well as tested the solenoids on the pumps to make sure they weren't shorted internally and everything checks out ok. If I remove the wires from the pumps while the engine is running, I get a code for a low or open circuit. I removed the wires for one of the good cylinders and when I cracked the line, it has the same steady stream instead of a pulse. I am at the point where it seems like the EECM is not sending signal for it to fire the solenoids but I don't know if there is a way to test for this. Any insight is greatly appreciated. 

 

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[Mack Technician]

Don’t pull wiring. Check cylinders by laying a jumper wire across two terminals while it’s running. You cannot hurt ECU by doing it. They are not insulated because there is no risk of computer damage. If the lights are low you can also see a little dull blue spark and know there is power delivery. 

An EUP is constantly an open flow (open center) circuit out the top delivery port. In other words rail pressure is going to spray a constant stream, until an electric pulse hits it. EUPs are built that way so you can bleed them easily with no power required to move air through. When your EUP is receiving no signal it is sending rail transfer pump pressure against the injector nozzle, when it pulses, it delivers high pressure and nozzle opens. That’s why if you have a cracked or leaking tip on an injector nozzle they smoke like a chimney, constant rail pressure would spray into the cylinder at all times, unrestricted. 

Use a jump wire to cut-out test and see if you actually have dead holes. Stop opening lines. Test EUP circuit with a fluke while running and compare cylinders. 

[fjh]

So have you run a valve set on the unit ? Does it have blow by? You could have bad compression on thous to cyls !If u swapped the pumps out and the problem stayed with the cyl then it sounds like a physical problem to me! Can you post All your symtoms ! Color of the smoke boost preasure and pyrometer  readings( under load) This might help nail it down! the engine should make 30-35 psi  boost  and pyro should stay under 1000 deg and the re should be little to no black smoke while pulling!