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MikeD 05-03-2015 11:26 PM

CAV Injector pump solenoid wire connections
Hi Guys,

I have also posted this on Boat Diesel, but maybe someone here has had a similar experience or knows the answer.

Anyway here goes....

I recently had to get the CAV injector pump and injectors reconditioned on my Cummins 6B engine, due to a fuel/water issue.

Coincidently, the hour meter stopped working at the time of removal of the pump.

Anyway, I investigated further last weekend and it looks like the mechanic may have left one of the wires for the solenoid off. The purple wire is connected to the solenoid, but the black wire is hanging free and I was unable to find a terminal to plug it on to. I am guessing the reconditioner left it off?

Anyway, I assume from the wiring diagram that this provides a ground (negative) for the solenoid. The solenoid works OK as it is grounded by itsī physical connection to engine, but is this the reason that hour meter is no longer working?

I have read about other hour meters failing over time, but it seems too much of a coincidence that this happened at the same time as removing the pump.

Would grounding this wire to the housing of the pump rectify the hour meter issue?


fryedaze 05-04-2015 07:28 AM

3 Attachment(s)
Mike what year is your 6BT. I have a 1989 with a Cav Lucas injector pump. It has a single wire and the comes from the ignition(purple) wire. I dont think the tach ties into the solenoid. Usually the alternator or a magnetic pickup at the flywheel. Maybe that wire goes to an oil pressure or temp sensor.

MikeD 05-04-2015 03:35 PM

Hi Dave, thanks for the reply.

My engine is circa 1993, I don't have the exact details here but will be up at the boat again next weekend.

Regarding the wires, there are four that leave the loom by the pump. 2 wires go to the oil pressure sensor and the purple wire to the pump solenoid. The loose black must be there for something, but I have been unable to find a terminal for it.

The temperature sensor is in another location.

I am pretty sure it was not loose before the repair but not 100%, so I am reluctant to do anything with it until I know its' purpose.

MikeD 05-05-2015 05:52 PM

Further to my message above, I have now ascertained that it is nothing to do with the loose black wire.

I managed to find a wiring diagram specific to my boat/engine and is says to leave this wire loose on netgative grounded engine installations, which mine is.

So it looks like it is hour meter that is definitely faulty.

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