1.9 DF: bypass air cut-off solenoid power supply

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DevonAid
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1.9 DF: bypass air cut-off solenoid power supply

Post by DevonAid »

Attention 1.9 DF owners or wiring diagram experts: Assistance appreciated!

The power supply to the bypass air cut-off solenoid valve on our 1.9 DF (with Solex carb) is currently daisy-chained from a power supply to both the automatic choke heater and the thermo-switch for the manifold pre-heater (but not the pre-heater itself). There are signs of non-standard connectors at the thermoswitch.

The Haynes wiring diagram shows the bypass cut off solenoid should have its own, solo power supply, but shows it coming from ‘connector 12’. Despite scrutiny, there is no ‘connector 12’ anywhere else in the wiring diagrams to see where it should be fed from.

I’m getting spurious behaviour from the air bypass solenoid (not always opening on engine re-start, therefore will not idle unless the engine is repeatedly started, when it finally ‘catches’ and then can idle). I’ve got about a 1 volt drop at the solenoid compared to battery voltage. I’ve replaced the solenoid. The carburettor earth wire is intact. I’ve cleaned out the carburettor (finding minor debris in the pilot jet, but still the issue remains).

I’ll go hunting for that voltage drop, but somehow feel there is something more to the issue than that.
How are other member’s 1.9DF solenoids wired? Any similar experiences or tips?

Thanks in advance
1985 T25 Devon conversion 1.9DF

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Mocki
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Re: 1.9 DF: bypass air cut-off solenoid power supply

Post by Mocki »

It needs a positive supply whenever the ignition is on, so taking its feed direct from the coil black wire will solve that issue , it’s where it should be .

As you have it, it’s only operating when the coolant temp allows it to have power, so when it is too warm for the choke to be on, it will have no power .
Steve
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DevonAid
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Re: 1.9 DF: bypass air cut-off solenoid power supply

Post by DevonAid »

Thank you, seems like a sensible solution.

I’m not aware I’ve changed the way this has been wired in nearly 15 years of ownership, so not sure why its become an issue now, but will follow this advice. Cheers!
1985 T25 Devon conversion 1.9DF

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DevonAid
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Re: 1.9 DF: bypass air cut-off solenoid power supply

Post by DevonAid »

Just following up on this: wiring mods still resulted in occasional lack of idle and needing to restart several times once it came off auto-choke, until it 'settled'.
After two replacement carb solenoids from our favourite supplier, I got a third one from Just Kampers (I know, I know) which looked like a different brand but they are not stamped with suppliers details.
Result: idle is now fine every time.
Its worth persevering with a hunch that something/a component is not right.
 
1985 T25 Devon conversion 1.9DF

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Mocki
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Re: 1.9 DF: bypass air cut-off solenoid power supply

Post by Mocki »

Thanks for coming back with this , it means a conclusion to anyone looking at this in times to come 
if you can put up the part number details for what other s can order that would be excellent ( do JK have part numbers ) 
Steve
tel / txt 07947137911
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DevonAid
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Re: 1.9 DF: bypass air cut-off solenoid power supply

Post by DevonAid »

Just Kampers part number, as requested:
JK PART NUMBER: J12064
1985 T25 Devon conversion 1.9DF

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