External psi gauge for cng

[sixb]

Anybody have a gauge for there cng? When I am on empty and the fuel light is on I notice the gauge on the dispenser equalizes at about 1500 psi when it starts to fill it up and goes to what ever the compressor will put out. Just wondering if the truck will run all the way to 0 psi. Thanks

[freedml]

Re: External psi gauge for cng

It will stall somewhere below 40psi. I have found dispenser gauges to be terribly inaccurate.

[maxman]

Re: External psi gauge for cng

The Ford CNG service manual I have says the system operates at 105 psi and switches at 75 psi.
Max

[Surfdancer]

Re: External psi gauge for cng

The dedicated F150 uses a pressure regulator set at 95 psi at idle and 3000 psi tank pressure. By the time the tank gets "empty" (around 250 psi), the regulated pressure should be 100 to 105 psi at idle. You can still hit full throttle flow at "empty", but not too much past that.

The dedicated F150 measures fuel pressure and temperature at the rear in-bed tank. These signals are used by the EEC to drive a fuel tank level gauge in the dash. Since these are inputs to the EEC, they should be able to be easily diagnosed by a OBD scan.

[Adrian]

Re: External psi gauge for cng

The Ford CNG service manual I have says the system operates at 105 psi and switches at 75 psi.
Max

Hi,
I've been trying to find a Ford service manual for a dedicated CNG F-150 for some time now...where did you get yours?
Thanks,

[maxman]

Re: External psi gauge for cng

ebay. There were several of them for the different years several months ago. They were going for around $40. Mine was on sale for $15, but it is for a 2003 and my truck is a 2001. The diagram showing the connecting plug in of the compuvalve is different in this book than the one for mine.
Most of the diagnostics in here use a scan gauge. Mine doesn't seem to have the ability, although it shows codes for two areas.
What would really be useful is the Ford manual for working on the actual systems. This is just a diagnostic book for testing the systems, and refers to the manual many times.
Max