generally the lp lockoff valve is located somewhere in the inlet line before the regulator, might even be on the regulator. There will be an electrical conncection going to it.

I finally got around to looking at this issue again. I got it to the no start issue and found it did have spark, so I am thinking it is a fuel problem. Can you tell me were the shutoff solenoid is?

josh.olivia at gmail

Don't rule out the distributor module, or the coil to soon. usually when they go bad the unit doesn't start at all but it is an electrical component. I would get the engine to the no start phase and then begin to trouble shoot, looking for ignition fire first. If the unit has an ecu on it, this can also cause trhe problem. I had one doing that very samre thing and itr trurned out to be the ecu unit. The ecu unit being the black box with thre multitude of wires running into it mounted on top of the engine. If you are getting fire, then troubleshoot the fuel system. This truck has relays in the dash that can also create issues when engine is warm.

If the engine runs well once it starts & doesn't smoke I'd rule out rings. I find temperature related issues are usually electrically based. I'd check the timing while cranking the engine cold, then again once the engine's hot. If that checks out then I'd check the fuel shut off solnoid- sometimes they stick when hot. Supply external power to the propane shut off solnoid & run engine until hot- turn off propane bottle til engine stalls (leave propane solnoid energized)- wait a minute & try to restart- if engine starts good- shut off solnoid is faulty- hope it helps

Thanks for the great information and ideas. Hopefully I will have sometime this weekend to work on it.

an ideal compression reading would be 150psi
but if engine has wear on it then you will not get that high of a reading, according to the engine manual any cylinder should not read anything less than 100psi on the guage. And there should not be a variance of any more than 70% from the high cylinder psi and the lowest cylinder psi reading.
ie: if the highest cylinder reading was 150psi then the lowest allowable reading on any other cylinder can be no less than 105psi.

You can do a compression check if you like but i would also pay attention to the LP Vaporizer, make sure its not freezing up. Also check your LP filter make sure its not stopped up.

Some things to check after it warms up is note the temperature reading on the guage (if it has one), make sure its not running hot. When you start the engine does it sound like its laboring hard when turning over?

Just a couple of things to consider :o)

No I haven't. I will check that this weekend. Do you know what the compression should be on a gm 4.3. Thanks for the help.

Hi , do you have check the compression? i think you have problems with the piston rings. check this or replace the rings.

Mayby valve leak?