Dual fuel LPG/gasoline schematic?
 

Hey folks,
I have a 1977 f100 4x4 shortbed running a dedicated,LPG system. There is no gasoline running through any part of the truck, but when I bought it, it came with a massive custom feul tank and a holley four barrel carb so I could convert it back.
The LPG is in two tanks sitting in the bed of the truck with solenoids to switch between them.

How would I go about wiring the solenoids and switches etc so my feul options are "big lpg tank", "little lpg tank" and "gasoline"?

also worth mentioning is that currently the motor is fitted with a gas vapouriser throttlebody.

G,day Most of the time there is a check valve between the tanks in the common hose to prevent the big tank for overfilling the little tank, I have not had a lot of luck with solinoids as they use upstream pressure (tank) to hold them closed so generally if the little tank was empty the big tanks pressure would want to blow thru the solinoid to the little tank. Ok the the way I would hook it up is to wire the LP to one side of a 3-way switch (on-off-on) and the gasoline lock off or fuel pump(relay) to the other using the existing power circuit to the center terminal to power either system. Then if you want to control the big/little tanks separately you would need another 3-way or your existing set up in that circuit leg. You will need a mixer to put on top of your holly instead of your staight LP carb. You might check your distributor spark curve to make use it has not been changed to an all LP curve
Regards

Thanks for your reply mate.
Theres two solenoids, one on each tank (manchester/apa style tanks) and each has its own filler valve, and the hoses that go to the engine meet up in a T fitting. Would I still do the same? Is a wiring/hose diagram available?

I know im not meant to.be playing with lpg systems because Im not qualified but bugger the law LOL :)

Yes just interupt the power to those solinoids when you want to shut down the lp.
Any way you could email me some pic's of the system from the tanks to the engine?
I might be able to cobble a rough drawing up, but I am not known for my artistic talents =)

jengland@gasequipment.com

regards

Yep, shouldnt.be a problem, you cant really see much but I should be able to get a few shots.

http://www.pngtechnologies.com/PDF_F..._Schematic.pdf

This gives a basic layout you can edit to suit your setup.