Mrfixit,

Thanks so much for the suggestion. I have thought myself perhaps the supposedly new regulator was faulty. I contacted the seller and he only used it for a short period of time before finding out that he had a dead hole on his engine thus the reason for selling the regulator.

With that said I don't discredit your suggestion. When we purchased the new used regulator we also bought a rebuild kit. I will reseal the original regulator assembly and see if that changes anything.

Regarding your test suggestion I will submit some more info you may find valuable. When we had issues with the original regulator assembly we used a tiger torch with a flow valve so we could control the flow of propane into the carburetor. We were able to run the engine with the forklift propane tank valve off. Also on this forklift another mechanic wired in a toggle switch for the electric solenoid lock off valve. Without the toggle on the solenoid will never engage.

We tested the engine and with the external supply it ran, so we decided to start it with the external supply then turn the forklift tank valve open to see if the engine would stay running. When we tried this it wouldn't which is when we came to the conclusion that it was a fuel supply problem. We found that when held about 2" above the carburetor the engine would run, any higher and it would die. This all seemed normal and pointed us to the direction that there is no propane getting to the carburetor, not too much propane.

My friend being who he is went to a local forklift shop and they sold him an impco regulator and convertor two pot system. He installed the system and we again attempted to start the forklift with no luck. We again tried the external propane supply using the tiger torch and the engine ran again. From my research the impco system uses some sort of a membrane vacuum operated valve on the carburetor to allow a vacuum to be pulled to start the flow of propane vapour from the convertor. We tested the operation of the new convertor and regulator and both seemed to work properly. The vacuum valve worked, we tested to verify good propane out of the regulator by disconnecting it from the convertor and using a vacuum pump to open the vacuum valve on the regulator. After this we used gentle shop air on the convertor while drawing a vacuum on the propane outlet port and the convertor seemed to work as designed.

At this point I told my friend you can't start mixing and matching systems, you need to use all the components from one system. I figured that we must have a missing piece that is required for the impco system not present with the current Aisin system. This is when we decided to purchase the new used Aisin convertor/regulator that was the identical model to the first. When we first installed the new used unit, it started and ran fine for an entire day. We stopped and started the engine and had a stable idle and everything seemed good.

It was over the next few days that I later found out the engine stopped starting again. It is possible that there could be an issue with the new used regulator so that isn't bad to check but I felt I would explain some more background testing.

I am going to reseal and test the original regulator assembly to see if that fixes the issue. I also read that some forklift systems route power through an oil pressure switch to the fuel lock solenoid. I will test to see if this forklift is the same. Perhaps the solenoid is only working intermittently which is why sometimes you hear propane flow after or during cranking and sometimes you don't. I will post back with the results.

Thanks again for the suggestion Mrfixit, it's appreciated.