We have a older forklift it will start and run for about 10 minutes then die then it will run about 30 seconds die start die until it sits then it will run 10 minutes and die. It will run on gas not real good it hasnt been on gas in years. It has a vacuum LP valve that is working and the converter is new. I put a low presser gauge on the converter and it has presser even after it dies. Its also fireing the plugs after it dies. I have worked on alot of LP engines but never had this problem.
Do you have a good flow of hot water (coolant) to the propane converter? Sounds like it might be freezing up on you.
The converter is hot so i dont think that is happening and it always has presser on the test port of it. They were useing it today i need to adjust the gas carb or get the propane to working.
try pulling off the fuel hose from the converter to the carburetor when it dies, crank the engine over and see if you have fuel (vapour) flowing out of the hose. That will narrow it down as to what part of the system is acting up - supply or mixer. Is it an electric or vacuum lock valve?
I have tryed that and it does have propane i even put a low presser gauge in the line and it had presser for a while after it dies.
It's got to be in the mixer then, or what ever metering device is above the carb.
I have been working on it some every day this week but got no were. I found out that i can start it on propane it runs good for maybe 15 minutes then starts running ruff then it will die then i can switch it to gas and it will run for a while and it will start running bad and maybe die. I have tested to see if it had fire at the sparkplugs and it has spark but it is hard to see or is maybe weaker than when first started. I thought maybe low voltage to the dist but it always has 12 volts. I am thinking about buying a new dist.
How about a condenser?
Is it point or electronic ignition? What you describe is almost classic electronic ignition bad stator coil. They crap out when hot, run again once they cool off.
Have you checked the propane filter? Sorry, didn’t see the ignition issue til after I posted.
Its electronic one hot wire to the dist coil is built in to it. It does sound like a dist problem but i never saw one act this way.
If a points and condenser distributor is either the condenser or the resistor block (some are built into the coil), reduces voltage at the points to around 9v, bad or weak condenser will do this.
so it's GM style HEI ignition? Check your cap & rotor. They burn up real bad.
Center contact is bad for self destruction, then affects coil. If a Hall effect like a Chrysler the small coil under the rotor goes to hellandgone.
I think monday i will order a new dist that will ether fix it or narrow it down.
if it has an external coil it could be that. I have had one act like that on a ford pickup. runs cold dies after 30-45 min. cool it off and runs again.