Hi, I recently purchased a 94 CNG Dodge Caravan and it worked great for about 10 days, then it suddenly stopped starting. It turns over fine, has about half a tank of CNG but refuses to start. I tried the on/off code test and received no codes back but 55. I’m not the best with cars, but am hoping this is something my friends and I could fix ourselves. Any idea what it could be?

 

Just a wild *** guess as I know nothing about how those systems work, but have you tried a new tank of gas? Just to rule out that the previous owner didn't fill half the tank with compressed air ?

 

Any noticeable symptoms when it died? Stumbling/rough idle or surging? Did it die suddenly while driving or you drove it one day and it wouldn’t start the next? Any odd smells, such as burning oil or coolant?

It’s possible the fuel gauge is incorrect and it’s empty.

Remove the CCV hose (connects from the air filter box to the valve cover) and use starting fluid IN SHORT BURSTS through the port while a helper cranks the engine. If the engine starts, it is a fuel supply problem. If it doesn’t, it’s a spark problem.

USE CAUTION AND DON’T USE TOO MUCH STARTING FLUID!! CNG engines are much more sensitive to starting fluid than gasoline engines. A shot or 2 just to see if it will fire is OK, but trying to run them on starting fluid alone can quickly burn valves or blow head gaskets. If you’re certain the starting fluid is getting pulled into the intake and it’s not firing, consider it a spark supply problem.

 

Nah it seemed perfectly fine before it died, I was sitting in it for like 30 minutes and then turned the car off, came back and it refused to start. I guess it’s possible it’s out of gas but I topped it off with CNG on the 21st and it wasn’t used much and has now been dead for 4 days.

I will try doing what you said though, thanks for the help i’ll let you know if it works.