Electric Choke Switch questions

[Brynjminjones]

To give a bit of background before I start:

My 1991 Waggy is set up for dual-fuel, with the original carb for gas and a propane mixer bolted on top.
It runs great on gas with plenty of power, but is very under-powered on propane and doesn't idle as well.

This is my first carbureted vehicle so I'm really learning from scratch here.

Before I go in over my head and start playing with timing and tuning, I want to get everything set up properly.

Now, I recently noticed that my electric choke switch is disconnected with the connector just hanging loose.
I'd have thought that this would have caused problems running on gas, but it starts (hot and cold), runs and idles really nicely.

Is there often a reason that people might disconnect this; can I just plug it back in again or will that screw everything up?

[JeepJeepster]

Not really any reason to unhook that. See if its getting 12+ when the Jeep is running and hook it up. The choke also uses a vacuum pull off but from what I remember, it wont open the choke all the way.

Be careful, if that wire grounds out it will quickly burn the Jeep to the ground. The carb emission wiring is not protected with any sort of fuse/fusible link.

[tgreese]

The choke on these carburetors is thermoelectric; that is, it opens from a combination of electric heating and indirect heat from the exhaust gases. There is a passage in the intake manifold that delivers exhaust gas to a stove that makes filtered hot air (not exhaust fumes) for the choke.

The electric side boosts the opening speed. The switch is an oil pressure switch, so that electricity is only delivered when the engine is running. This prevents the choke from opening when the key is on and the engine is not running.

Typically you need both electricity and hot air for the choke to work properly. Since the rest of the fuel delivery has been modified, the choke may have too. There are all-electric choke mechanisms available that could have been swapped in to your Jeep. Also, the choke will work fine without the pressure switch as long as you don't let the car sit with the switch on.

[thumperjohn151]

Ok - Have you checked for vacuum leaks anywhere in the setup? carb-to-manifold? LPG rig-to-carb?

[Brynjminjones]

I just wanted to say a quick thanks guys, as well as put a follow up in case anybody's interested.

It would seem that reconnecting the electric choke has sorted all of my high idle issues. Seems a bit odd to me, as the electric choke switch was already disconnected before the high idle started, but it's better now.

The carb has since had a rebuild too as it was shooting gas everywhere, so now it's better than ever!