can't get cng to work

[nytech]

I have a 97 ford expedition bi-fuel with 2 large tanks. I just bought my cng at auction and I tried to fill up at cng station, but I can't get any cng pumping ( neither could attendent and pump was working). I tried the on/off switch, I tried opening and closing tanks, but I cant figure it out. I am in the Bronx, NY and would appreciate any help on whats wrong or who I can bring it to, to fix it...

[Lakewood90712]

Re: can't get cng to work

Very likely the tanks are FULL , and the fuel tank pressure tran$ducer is bad $$$$. Most bi-fuel systems will not let you try to run on cng if it THINKS the tanks are near empty , even if actually full.

Does the fuel gauge indicate 1/4 tank or less ?

Do you have any blown fuses ?

[maxman]

Re: can't get cng to work

My 2001 F150 had a bad compuvalve. I thought it was out of CNG. When I went to fill it, it only took a bit, then the pump shut off. It was full. I'm not sure about what the transducer is nytech talked about. Is your a GFI with the compuvalve?

[CraziFuzzy]

Re: can't get cng to work

There could be a lot of different things causing this. We'd need to know what brand conversion is on the vehicle. My 2000 Expedition for instance, does not care what the fuel pressure is, and will just run on CNG until empty and it stalls out. Some other conversions will automatically switch to gas when they sense a certain low level on the CNG side. I know you said you checked the tank valves, but have you checked the 1/4 turn shutoff valve? Most times it is in between the fill connection and the tanks, so if it is shut, you won't get any gas in the tanks.

Oh, and the transducer that was mentioned is the device that measures tank pressure, and tells the CNG computer. If it is bad and is saying the tanks are empty, some systems won't allow you to run on CNG and would just force the switch to gasoline.

[maxman]

Re: can't get cng to work

Another thought could be the tanks are full, but the line may be shut off. Look for a manual shutoff valve somewhere between the tnaks and the engine. I think it's somewhere near the CNG filter under the the vehicle. I've read where many times they get shut off when selling at auction, either manually, or by removing a fuse.
Good Luck
Max

[cngnyc.com]

Re: can't get cng to work

There could be a lot of different things causing this. We'd need to know what brand conversion is on the vehicle. My 2000 Expedition for instance, does not care what the fuel pressure is, and will just run on CNG until empty and it stalls out. Some other conversions will automatically switch to gas when they sense a certain low level on the CNG side. I know you said you checked the tank valves, but have you checked the 1/4 turn shutoff valve? Most times it is in between the fill connection and the tanks, so if it is shut, you won't get any gas in the tanks.

Oh, and the transducer that was mentioned is the device that measures tank pressure, and tells the CNG computer. If it is bad and is saying the tanks are empty, some systems won't allow you to run on CNG and would just force the switch to gasoline.

Some ford contour have the 1/4 turn shutoff valve within the fill connection and the tank, I have another ford contour of same year but i can't find the 1/4 valve conection in there,did anybody know where else could be?