Sn: cat0226dehrd01968 Looking for a schematic to follow wiring, identify related relays to the 12v primer pump. Changed the fuel filter and couldn’t get the machine to re prime, forced it to by cranking making the injection pump pull the fuel. Noticed after running filter never filled completely. Checked power at primer pump and none. Checked fuses in cab.
Did you also clean or replace the suction screen that is part of the electric priming pump assembly.? It is shown as part of #13 in the attached illustration. If that screen is plugged it could explain why the filter bowl assembly still has air in it. Try activating the electric priming pump this way. Turn the key from ON to START very briefly, then release it back to the ON position without letting the engine start. Does that make the pump start up.? I will send you an electrical schematic. Check your message inbox.
Yes I did change the small suction screen, it’s clean and clear, I was not touching the key to the start position, just turning to the on. I will try that and check power again. Thank you for the information and schematic
No power still even bumping the key, I will dig into the wiring schematic, thank you for that.
Head for the fuel pump relay in that case so check for power and whether or not it is getting a signal from the ECM on wire #365 Yellow. There are five relays all the same part number, so you could swap something like the stop lamp or backup alarm relay as a test.
After a lot of testing, I have continuity from 87 to the round connector behind the cab, from the connector to the pump I lose it. I removed the harness from the machine and found a break in the pk 327wire. Amazing it broke with how well shielded and built this harness was. Will be getting ahold of the dealer to see about cost of a new harness being I have an erratic egr code as well and seeing this harness connects to the engine harness I will probably air on the side of replacing to possibly fix the egr issue rather than repair. Thank you for all your help much appreciated.
Be sure you're sitting down when you ask the price of a replacement harness......... Is it Ref #12 on the attachment.?
It is the other half, machine body side not cab side. Dealer is also struggling to find it. I’ll do my best to not tip over when they tell me a price. On the wiring schematic it’s location c-14,ej c7 connector 4 then to to the pump, mating connector within the harness is to the engine harness location d-14 c-c4 connector 4 It comes from the back of the cab goes down the frame of the machine and back to the rear proper pump
You mean going from here to the right on the schematic...? That's the engine harness - 495-4794. which is a known problem for wire failures inside the harness itself, despite the protection outside. Question: Does the location where the 327-PK wire has failed happen to be where the harness is pulled tight around a corner and zip-tied in place to one or more ladder clips.? If so there may be some sort of factory support programme, although your machine might just be too old for that. You can find all the harness Part Numbers in a table at Grid F-1 on Page 9 of the schematic. The note below shows how to identify the reference letters of a particular harness. In the illustration you have Harness reference AG, Connector #4 connecting to Harness L, Connector #12.
Yes that’s the harness going to the right from there, better than I thought a little under $400. Thanks for pointing out the harness part number on the right side there. I Will have the harness tomorrow and hope it will solve the egr issues as well. If not I will proceed into diagnosing that. It has a 2791-10 code. But started with this primer pump issue first… one at a time. You wouldn’t happen to have any guidance on that egr code if after the harness install the code is still present would you? After about a minute of run time the engine will surge reving up and down sometimes almost stalling out. Your help has saved me an enormous amount of time, thank you again.
Here you go. 2791-10. EGR Valve Control : Abnormal Rate of Change. Troubleshooting is "Motorized Valve - Test"
So I replaced the harness related to the fuel pump issue, this solved the problem. When replacing it found another harness with chafing, bare wires. Replaced that one too. Moving forward with the egr code I removed it cleaned it and reinstalled. Code still present reving up and down still. Called the dealer 980 for a valve. Put the machine on a weight loss program so valves and intake and egr have been resolved but the machine to my surprise still is persisting with the reving up and down issue. Even with both items fixed. Machines not throwing any codes. Wondering if you had and direction to head to proceed diagnosing?