F-150 Issues...HELP!

[passngass]

I am in possession of a 2000 Ford truck and I am having trouble getting it to start up on CNG. Both CNG tanks are full of fuel and both run excellent on gasoline. When I attempt to start the trucks in CNG, you will hear the CNG tank click, but then the CNG(green) light will go out and it then switches back to regular gasoline. I can't seem to get the truck to start and/or run on CNG fuel. Any helpful ideas will be greatly appreciated.

[Lakewood90712]

Re: F-150 Issues...HELP!

Compuvalve..................................

$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

And backorder is about a year .

Sorry .

[Lakewood90712]

Re: F-150 Issues...HELP!

Have your Ford dealer run the VIN # and find the "Date in service" .

If it is less than 8 years and has less than 80,000 miles, it is prob. under the federal emissions warranty . Ford may pay if so. The part will still be on order for a long time.

[new2cng]

Re: F-150 Issues...HELP!

Is the Check engine light on? Mine did the same thing turned out to be the MAP sensor.

[cng]

Re: F-150 Issues...HELP!

My 96 F150 does sort of the same thing. Although, sometimes after driving a while on a hot sunny day i can restart it in CNG mode, but it will only run in that mode for a few miles before it starts to hesitate and then automatically switches back to gasoline mode.

[karlhafen]

Re: F-150 Issues...HELP!

Check out this TSB. I performed it on a 2000 bi-fuel and it did wonders for the idle quality. Please be absolutely sure that your tanks are off and you have ran down the pressure before you remove the screw in the filter!!!

[cng]

Re: F-150 Issues...HELP!

Thanks karlhafen, thats some great information. Now according to the range for the F-150's that this procedure is to be utilized is 1998-2001. My truck is a 1996 GFI CNG System (its got a straight 6cyl engine), but i am inclined to think that the Compuvalve operation and specs are very similar (if not identical) therefor the same procedure should be acceptable for the 1996 F-150.. which is factory installed. Now if someone knows more about why this is/might not, then please furthur inform me. Thank You!

[cnguser]

Re: F-150 Issues...HELP!

To those with the '96 F-150 trucks:
If you want to bypass the dealer or CNG tech service and dig into this on your own, I would suggest ordering the '96 Ford F-150 Shop manuals from www.Helminc.com.
Also check the box for TSB's. Watch for any other selections listed pertaining to CNG, in case there is a CNG supplement manual, etc.
Be certain the truck's CNG system is not an after-market add-on, or you won't get any help from the manuals.
The similar shop manuals for the 2000 Ford Contour include the CNG system option.
Likely so for your F-150.
Good luck!

[locosmotion]

Re: F-150 Issues...HELP!

Sorry but I have to add, I have the 2000 CNG shop service manual in PDF for anyone interested. (Contour, F150, F250) It is mostly worthless without the Ford NGS scanner with the special CNG add-on ($3500). For troubleshooting it asks you to read values and if the values are wrong the next line usually says replace the compuvalve. Also it contains none of the wiring diagrams for the CNG side which I believe mis-diagnoses 70 percent of all compuvalves.

[ashtonmotors]

Re: F-150 Issues...HELP!

If you hear the solenoid valve on the tank open and then shortly after the vehicle switches back to gasoline you probably have a faulty pressure transducer. The pressure transducer on the F150 is located on the high pressure regulator. It is a small cylinder about the size of your thumb. If the pressure transducer cannot send an accurate signal the vehicle does not know that there is any cng in the system. It automatically will switch over to unleaded. There is a very high probability that this is the problem. It is not really difficult to fix but you will need to purchase a new transducer.

This does not have the symptoms of a faulty compuvalve.

[cng]

Re: F-150 Issues...HELP!

Thanks Ashtonmotors and Locosmotion for the additional info, you guys are great. Does anyone have the F150 Manual in PDF format that Locosmotion mentioned. If so, then could you please forward one to me.... my attempts to pm Locos are not working. Thanks in advance.

[CNG MOTORS]

Re: F-150 Issues...HELP!

Transducer is difinately suspect but not likely. Add a additional ground to the tank valve, This is a common problem with these F150's. Champion quated me $2500 for a new compuvalve and I fixed the problem for $10. Also check the two fuses just forward and to the left of the compuvalve.

[mazzy]

Re: F-150 Issues...HELP!

Ashtonmotors,

It sounds like that is happening to my 99 contour. Where is The pressure transducer ?

Do you know of any on line manuals/diagrams that will help me find this and change it?

Do you have to empty the tank before changing the pressure transducer?

Thanks,
Mazzy

[UtahGasBill]

Re: F-150 Issues...HELP!

Thanks Ashtonmotors - what a GREAT bunch of guys down there. I changed out the FUEL PRESSURE SENSOR on the HIGH PRESSURE REG like you suggested and BINGO, FIXED!!! I am once again running on CLEAN, NATURAL, UTAH CNG!!!

Thanks to all the guys at ASHTON MOTORS.

Bill



PS - Thanks to CNGMOTORS as well. I did first try the ground and the fuses, but sadly, they were not the problem... dang it!!!

[UtahGasBill]

Re: F-150 Issues...HELP!

DANG IT!!!!!!! It ran GREAT for ONE day. I think it must be a ground issue... I am going to take it to ASHTON MOTORS and let them take a look at it.

Bill