Engine ruuning on (dieselling) fix

[Rod 2500S]

The attachment engine cut off solenoid valve 2.JPG is no longer available

The attachment engine cut off solenoid valve 2.JPG is no longer available

Hi Lads and Lasses
My 2500S being Australian delivered was fitted with anti pollution stuff (carbon canister, exhaust gas recirc etc) Also added was an anti run on solenoid valve which contrived, through devious Lucas and Leyland electrical magic (not) to switch manifold vacuum to the top of the float bowls when the engine was switched off.
When I got the car the Exhaust gas recirc had been deleted (Well done PO)
So far so good then, until the solenoid valve slowly fails over time, gradually applying vacuum to the top of the float bowls.
If you don't realise what is happening the cure is to richen the mixture, by this stage the motor is fairly tired and you just put it all down to wear.
I discovered all this when I did a vacuum leakdown test on the solenoid, swore violently then went looking for a replacement.
Imagine my annoyance to discover the part is "unobtanium" and cannot be repaired.
Local Gurus said "delete the lot and leave the Rocker cover breather tubes in place" , which I did.
OK So I have a high mileage engine with significant carbon build up which causes the run on problem. Leyland fitted this solenoid for a very good reason.
So how do we recover the situation without a OEM replacement, ok a little research found a valve intended for a small coffee machine with the required three ports and two positions which runs on 12 volts. IE Valve off ports 1 & 3 connected, valve on (ignition switched) ports 1 & 2 connected.
If 3 is Manifold vacuum and 1 is the float bowls then when the ignition is switched off the valve connects manifold vacuum to the floats and Et Voila, the fuel is pulled up and away from the jets and the motor stops.
With ignition on (1 & 2 connected) the valve connects the floats to the existing fuel overflow/return line to the tank, which is what nature intended.
OK see the pics if your confused, these should help.
The solenoid draws 240 milliamps and can be connected to any handy ignition on source (not the coil if it's ballasted) Readily available from the usual source at a few Quid.
Thank you for listening and I hope this helps those of us with this problem.
To head off any comments about Carbon build up etc, yes a full decoke will happen shortly.
Have fun all
PS yes the pics are out of order sorry but the web site is adamant that this is where they shall be, regardless of my wishes.

[Charles H]

What a neat and sensible solution.

[Rod 2500S]

Hi Charles
yes it's Triumph's solution without the emissions crap.
I've got a photo of the valve bare fogot to attach it
Cheers

[Rod 2500S]

The final version of the engine cut-off valve now incorporates a Non return valve in the fuel tank/float bowl breather line. When running this allows air to the tank and floats for full fuel flow.
This was found to be necessary on my car due to the multiple changes to the emissions set up. The original set up allowed air from the carbon emissions canister to this line.
As far as I can tell late model Australian delivered cars had a sealed fuel cap system vented into the canister.
Yours mightb be different.
The valve is an NRV from a brake booster. Any one will do, as long as its fuel resistant.
Now back to the Colortune because the carbs will surely now be rich.
Cheers all
Rod

[Rod 2500S]

Gday
An update on how this should be configured. It turns out that the valves are DEFINITELY not rated for continuous operation. Mine just failed after 1.5 hrs operation. Not continuously but in short trips.
Investigation reveals an interesting thing, these happily pull in at 6volts and run reasonably cool. I suspect the Chinese makers have relabelled 6 volt units to sell as 12volt, just surmising of course, can't prove this.
Anyway the cure is to use them in the normally closed port config no power to them and then wire in a switch to push when you shut down and she runs on. Put this under the dash somewhere.
Or run a "ballast" resistor to limit the voltage across the solenoid to 6 volts, this should work also. But even at 6 volts these may not last too long.
Kill switch for me it is.
Cheers

[torque2me]

Thanks for that interesting post Rod. Those "parts" people are worth their weight in gold on occasions like these.
Kev