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Old 07-29-2022, 12:59 PM   #1
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Power to the fuel pump

2007 R26 Workhorse Chassis:
Fuel tank is on the ground. There is no power to the four terminal fuel pump
plug. New relay in rear ccm K7 position, fuse is good.
I need know which wires are the pump and which are the gauge and can the fuel pump be dry tested?
Thank You SARGE.
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Old 07-29-2022, 01:45 PM   #2
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Quote:
Originally Posted by sarge1946 View Post
2007 R26 Workhorse Chassis:
Fuel tank is on the ground. There is no power to the four terminal fuel pump
plug. New relay in rear ccm K7 position, fuse is good.
I need know which wires are the pump and which are the gauge and can the fuel pump be dry tested?
Thank You SARGE.
Electrical schematics are near the bottom of this list:

Workhorse Technical Info.

Hope you can find what you need there, I don't know the answer to your last question. Good luck!
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Old 07-29-2022, 03:40 PM   #3
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From edgray's link, thx!



Determine which black goes to the fuel sender (purple)
The other black will be the pump motor (gray)
Or A & D on the connector.
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Old 07-29-2022, 03:42 PM   #4
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Then the Gray wire gets power from the K7 relay
Check the output to the gray wire / does the K7 relay pick up?


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Old 07-30-2022, 09:59 AM   #5
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We’ve seen this a few times now caused by an internal failure in the rear CCM. We used to have a test CCM we could rent out to diagnose issues like this but I think the last person we did that for never returned it to us :(
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Old 08-09-2022, 04:34 PM   #6
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No power to fuel pump

Got gas tank back in place today.
Ran a jumper wire to fuel pump from 12V lug in rear CCM.
Engine started and ran till jumper was removed from power.
I am suspecting rear CCM is bad.
Opinions please!!
SARGE
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Old 08-12-2022, 05:41 PM   #7
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You are most likely correct in your assumption. Cannot remember whether it is the J5 or J2 connector on the Rear CCM which provides power to the fuel pump. As you have the wiring connection diagrams via Ed Gray, you should be able to fabricate a jumper to connect power to the fuel pump from the connector. I have had a Rear CCM failure as posted in old posts on this subject. Had to replace RCCM and solved the problem. However, periodically the coach will stop due to the plug going to the RCCM not making a good connection due to ham handed techs working on the plug to troubleshoot the problem.

If I have my wife start the coach and I jiggle the plug, I have found the coach will start. I have since changed the pins on the plug and jury rigged a support for the power cord, seems to have resolved the connection problem.

Hope you find the issue and get it resolved.

Best regards
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Old 08-15-2022, 07:34 AM   #8
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No power to fuel pump

Thank you all for your help!
When I dropped the gas tank, I found someone had ran a wire from one that is hot when ignition switch is on to the gray wire to the fuel pump. I found that this wire did not turn on the fuel pump.(Don't know why!)
I then ran a jumper from a 12v lug on the rear ccm to the fuel pump, the pump worked. I reinstalled the gas tank and put a switch and fuseable link at the rear
ccm. The engine runs as long as the rear switch is on.
I need to find that gray wire as far back to the rear ccm as possible and check for continuity.
On the ccm, does anyone know if their programed per VIN #.
Thanks again SARGE!
By the way, I, for the life of me cannot my heads or tales of wiring schematics!!
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Old 08-15-2022, 01:28 PM   #9
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I can help with the schematics, but need a little help. I re-checked the prints provided and now see there is another set for the R26, which says "Original"
I looked in there and the fuel pump power in those are fed from the K1 relay and fuse #1 (Rear CCM)

Same gray wire but it comes out of connector J8(G)
Maybe check that.
EDIT: I mis-typed Should say "Original"
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Old 08-15-2022, 04:42 PM   #10
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Went back to my set of drawings the fuel pump is shown on sheet 35 and it shows K7 feeding the fuel pump and is protected by fuse 12 on the RCCM.

However when I go to sheet 11 which is the picture of the RCCM it has a pic of K7 relay but it does not show a K7 in list of relays and says fuse 12 is not used.

Finally drawing 22 sheet 2 of 2 shows the RCCM schematically and zone D6 has the K7 relay as feeding the fuel pump. Confusing for sure.

On my sheet 11, it shows Fuse 1 and Relay K1 on sheet 11 pic of RCCM as feeding TCM ignition switch.

You will most likely be able to continuity check back to the J5 plug easily, however, figuring out whether K1 or K7 feeds the pump will be more difficult.

Can I assume that the coach ran for you at some point and then had the issue?

If it did run for you, and now does not, and you found a wire jumper from the ignition wire to the fuel pump, then K1 or F1 would be suspect to me unless you get some other indication the ignition sequence is trying to start the coach which would say that the ignition sequence will at least begin. (Sorry in advance to the verbose wording)

In closing, believe part of the engine startup has an oil pressure sensor contact involved in the starting sequence. (Not to muddy the waters)
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Old 08-15-2022, 04:58 PM   #11
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I give up.... adios.
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Old 08-15-2022, 07:09 PM   #12
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Oldweb;

Not sure if my post offended you, but if it did, I am sorry for that.

Hope you resolve your issue Sarge1946 and will bid my adeau.

Best Regards
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