1999 F250 BiFuel idle problems on CNG

[HELCOWESTVIRGINIA]

I have a 99 F250 that does not IDLE on CNG. Also when you tramp on the thorottle, it switches over to Gasoline. I have so far drained the tank, replaced the filter, i removed the compuvalve and tore it apart and cleaned the jets inside but still the same problem. The only other mechanical part is the Regulator. This is not leaking so i figured it was good. Any suggestions?

By the way, these compuvalves are not that difficult to clean. Just takes a little bit of patience and general mechanical knowledge.

[HELCOWESTVIRGINIA]

Re: 1999 F250 BiFuel idle problems on CNG

Part two...Well after taking the regulator apart, we found where the missing filter got to. It must of fell apart and got into the input side of the regulator. The line was jammed full back four inches before the regulater and inside. After taking the regulator apart and putting back together, the truck is running a whole lot better. It no longer switches over to gas and runs very well mid to top end. However, it still does not idle. Has anyone out there ever had this problem????

HELP!!

[sdhamblin]

Re: 1999 F250 BiFuel idle problems on CNG

Sorry, I've got a 2001 bifuel F150 and I don't know why yours won't idle. That's great that you got it to run otherwise though! Mine switches off when the after the engine warms up, or it goes under a load, so I've wondered about trying to clean out the compuvalve by hand. Can you give any details on how to turn off the fuel supply before I unbolt the thing? Any other helpful hints? I've worked on my own vehicles a lot, but not on gas lines, so don't want to cause a leak etc.

Thanks and good luck.

[HELCOWESTVIRGINIA]

Re: 1999 F250 BiFuel idle problems on CNG

The cng tank has a 12 volt supply that controls the valve opening. If you are to work on the cng lines, disconnect the battery terminal first. As far as the compuvalve goes, I removed the valve being careful in remembering where all the wires and vacuum lines were connected. After the battery was disconnected, bleed the Gas by cracking open one of the supply lines at the compuvalve. (Do this outside so the gas can disapate) On one side of the Compuvalve contains the electronics and really has no bearing on cleaning. Remove the solenoids by removing the cover nuts, then the covers, then the magnetic housings, and dont forget to mark them so you get them put on in the right position. After the Mags are off, you can unscrew the bases which have a spring and plunger under them. The plungers work on top of a bank of Jets that allow the gas to be released sequentially. After All solenoids are removed, you can then remove the Idle injectors. Then you can clean the base and jets and reassemble. Inspect all your o-rings and replace if worn. Also, Ford uses O-rings in almost all connections or a Brass washer on the Flare fittings. Be VERY Carefull not to loose. I dont know where you could get a replacement for these.

[dtbouck]

Re: 1999 F250 BiFuel idle problems on CNG

Just a stab in the dark but you may try cleaning the air flow sensor. My contour had trouble idling and cleaning the sensor cleared it right up. A can of air flow sensor cleaner is about $7 at any auto parts store.

[chester]

Re: 1999 F250 BiFuel idle problems on CNG

any tips for cleaning the regulator supply, i got one that is hard starting on cng, runs great on gas. less hard starting in summer when engine warmed up for a few miles.