Going behind someone that just put brand new injectors in machine due to it having a hard time starting and you used to have to use either and this is a common rail with high pressure fuel pump and it ran for about 10 mins and the fell on its face they said, so I go out there they have replaced relief valve and rail pressure sensor and basically everything besides the pump but they don’t have Cat ET which I hook up to it and see fuel rail pressure at 50 psi when cranking it and I was like no good so I do the fuel pump solenoid test it test and also it’s brand new the replaced that as well injector solenoids are good too and I pull the the line off the low pressure pump we got fuel coming out of there also NO CODES at all on this machine and I just check the no start parameters and all speed sensors are working everything is reading good and the fuel injection disabled is off so if my diagnostic is correct there really is nothing else it could be but the high pressure pump right??? Also machine tries to start on either but won’t start on either now PHX1056
Welcome, Justin, to HEF. You'll find a wealth of helpful folks here willing to bend over backwards to help. I recommend posting the serial number so folks can pull up the exact specs on your machine. Oh, and using periods in your messages helps us 'old' folks to better understand the issue.
Ah yes sorry about that and I put the serial number at the bottom for some reason
Great- I didn't realize that was a serial number as it seems pretty short but maybe the Cat experts understand it. Best of luck with the fuel issues.
If according to you only have 50psi in the HP fuel circuit while cranking then why not try capping the injector lines at the fuel rail and crank the engine for no more than a couple of seconds to see what the pressure does. If the pump can't raise pressure when dead-headed it's farked - unless of course the rail pressure relief valve is leaking. Have you tried pulling the return line to check if any fuel is coming back from the rail when cranking.? It goes without saying this test has to be done CAREFULLY.
Oh I see I just saw this I was on it today and the pressure relief valve is brand new there is a steel line that comes off the bottom of pressure relief valve with a banjo bolt through it that runs to the top of fuel injection pump. When I push the primer pump it starts pushing fuel through that steel line that’s under pressure relief valve into a hose that goes back to the tank so when I hit primer something internally on pump is not closing and allowing fuel to go straight back to the tank. So it says that I think in sis it shows that line is for when the pressure solenoid is sees too much pressure internally in pump it can regulate some of it back to pump but it shouldn’t be doing that if it’s turned off and just being hand primed right ?
Also to note I did pull out the 2 little check valves on top of injection pump head and spring and stuff looked fine but on the end of one of the check valves . I noticed this really small little sliver of metal stuck to it so I was also thinking the only way that could’ve got there was from the pump internally.
Should I have any fuel going back to the tank just from the hand primer like I have now ? Thanks for the help
From what I recall the rail pressure relief valve is supposed to open at some crazy high pressure like 25,000psi. I may be off on the actual number but it’s stupid high. Hopefully someone else can confirm that.
The only fuel going back to the tank, from the primer bulb, should be return fuel. Do you happen to have a check valve, you could put in after the the fuel primer bulb? Might be bad in the primer bulb.
I don’t so that line that comes off primer goes to injection pump and that fuel is traveling through fuel injection pump and into line on the other side of pump and back to tank like it’s something inside the pump that’s supposed to be stopping fuel from going back to tank but it’s not it’s just free flowing through pump straight back to tank from the hand primer which like Nige said should hold up to 20k psi in that system
Like here it says it’s supposed to push air out of pump back into the tank but the only thing being pushed out of the injector is fuel not air so I can’t get it to hold pressure with primer cause it just pushes out of the pump internally and this machine has new injectors installed in it
What if the common rail wasn’t moving?
I’m sorry I don’t have a lot experience with type of system what do mean by the common rail not moving ?