F-150 bi fuel troubles

[Curtis D]

I have a 2000 f-150 bi fuel with 76,000 miles on it.Ran great on either fuel up till yesterday.Now it runs on ng if you keep a little pressure on the accelerator,but dies if you let off.Still runs perfect on gasoline.
I had a shop diagnose a leaking regulator a few months ago because I had mentioned that I could smell natural gas from time to time.Could the regulator be the culprit here.I am thinking it might not let enough ng through to idle but when the accelerator is down a little it does.
Anybody ever have any experiences with this type of behavior.

[noneed2panic]

Re: F-150 bi fuel troubles

I have some parts on ebay if your interested let me knoe and ill end the auction

[Curtis D]

Re: F-150 bi fuel troubles

Update,
Replaced the regulator with a new one and the compuvalve is leaking quite a lot from the low side solonoids now.Truck idles and runs fine but I don't dare to drive it on cng for fear it will catch on fire and or explode.
any one ever here of the compuvalve leaking like that?

[jblue]

Re: F-150 bi fuel troubles

Replaced the regulator with a new one and the compuvalve is leaking quite a lot from the low side solonoids now.

You might try a full disassembly/cleaning/reassembly of the compuvalve as described here:

http://www.cngchat.com/forum/showpos...0&postcount=11

in the hopes that you might be able to find the source of the leaking and fix it.

So did this replacement compuvalve come from "noneed2panic" or did it come from Russ Dearing in MA?

[boomr]

Re: F-150 bi fuel troubles

I just took my compuvalve apart and cleaned it and it was not as hard to do as you would think. Check the thread "rebuilding compuvalves" . It was pretty easy and you can do it yourself. I do not have much mechanical know how but found the instructions pretty much spot on. Not sure if it works yet as there is no power to my switch for some reason but I am working on figuring that part out. GOOD LUCK

[Curtis D]

Re: F-150 bi fuel troubles

Thanks for all the input.
I have not replace the refurbished compuvalve on this f 150.I replaced the regulator with a new one I found on EBay.The regulator was leaking so when the truck quit running on cng at low rpms I assumed it was the leaking regulator.I think what has actually happened is the low pressure solonoids in the compuvalve are faulty,dirty who knows. It runs great if you keep some pressure on the accelerator.
My next step will be to take it apart and clean it. I won't pay thousands of dollars for another one.We need to figure out how to lose this weak link on these trucks.There are alot of them out there but not alot of parts.
Thanks again for all the input and I will let you Know what I find out.

[Curtis D]

Re: F-150 bi fuel troubles

Well I took the compuvalve apart today and cleaned it with alcohol.(see attached pics)It was not really dirty at all.After I reinstalled it it leaked from one of the two low flow valves like before but quit leaking after a half hour or so.Just like it did after I put in the new regulator.But now the truck runs on cng great except for occasionally it will stall while idling.I could not get the 5 high flow solonoid plungers out even after creating a slot in the tops for a screw driver.I left them in and poured a pint of alcohol through using cue tips where possible to scrub.Although none of the cue tips seemed dirty there were some black flecks in the alcohol that washed through the compuvalve.
I'll update this if things change.(and they probably will).

[jblue]

Re: F-150 bi fuel troubles

I'll update this if things change.(and they probably will).

Well done! Thanks for the update and pictures.

[Franz]

Re: F-150 bi fuel troubles

The plastic injector holder on the low flow injectors was known to develop a hairline crack, and of course, they are not available for sale, anywhere, new. The black flecks are usually seal compounds from somewhere in the system, and it can come from long before your vehicle, in the compressor station.

These flecks and other foreign matter can work past a regulator filter and have been known to stick in a high pressure seat in the primary regulator and allow uncontrolled higher than desired pressure and a leaking low and high flow injector at the Compuvalve.

Using alcohol works to flush the system although I usually start with mineral spirits to get the wet stuff out first, then alcohol to final flush out. I have done this on the vehicle too, by removing the fuel line between the primary regulator and the Compuvalve and putting the solvent in, then running the engine. The flushed stuff will pass through and get burned.

Get prepared for some smoke though but it goes away after the catalyst gets hot.

Franz

[Curtis D]

Re: F-150 bi fuel troubles

Well now I have no power at one of the two positive leads to the low flow injectors.The injectors work and so does the truck if I wire a 9 volt battery to the injectors. Not the pulsed voltage they are suppose to receive but it idles and accelerates well.I found continuity through the wiring harness to the compuvalve spaghetti connector so my guess is no power out of the compuvalve.Probably the electronics.
I wish there was a schematic for the thing so I could diagnose it more effectively.