I have a 97 f-250 5.4 liter automatic. One day the engine light came on while on the freeway. I went to the store and when I came out to leave the parking lot it just died as if it ran out of fuel.

This is a dedicated compressed natural gas vehicle, no gasoline. The truck will fun fine if I spray starting fluid into the manifold but otherwise will not start or run on its own. So the ignition system seems to be fine. I pulled a 1152 code and checked the o2 senseors with a meter on the work bench and the values changed when exposed to differences in heat as the book says it should so they seem fine.

When I remove the fuel injectors as a tech suggested, because the may have all failed at once (who knows) there was pressure bleeding out past the o-rings at the fuel rail and when I checked at the filter (the coalesecing filter) I also had tons of pressure so does anyone have a clue what the heck is going on?

I sent all the injectors out to be reconditioned as I could see the small filter screens loaded with gunk, however this did not cure the problem once I put them back in and tried to start it....I did disconnect the battery to clear the memory prior to starting the engine.

One person on here thinks it could be that it needs a reboot with an Oasis platform? Problem is I am 200 miles from a Ford dealer who can diagnose this problem and my truck stuck at my house so a tow would be pretty expensive.

Any help who be greatly appreciated.

Sorry I bought this cng truck, next time I'll get propane because there is very little info on how to service this stuff.

 

I don't think I've ever even seen a CNG conversion. Hopefully somebody in the alternative fuels forum can help. Thread moved.

 

You've got a pretty rare bird if its a dedicated F150 produced by Ford. Ford made quite a few bi-fuel F150's, but I wasn't aware of any dedicated ones. I think they did make some dedicated CNG Crown Vics for Canada.

If your VIN starts with a '2', you might have better luck talking to Ford of Canada.

 

If it's a dedicated CNG vehicle, how does it use the injectors? I'm not real familiar with these systems, but isn't natural gas.. a gas?

 

Even though it is infact a gas it is still pumped through the fuel rails and injectors. as are the Propane ones. The power from these engines is very close to on regular unleded because of that.

 

Ford actually made a lot of dedicated CNG vehicles, Crown Vics mostly, but also F-250. My brother had a CV, now has a CNG Honda Civic. They use a similar EFI system as the gasoline ones, but not identical. They are "bank firing" rather than sequential. That means that all four on each side fire at once, just like many '90's vintage gasoline engined Fords. Since CNG burns so cleanly, the more advanced system is not necessary for emissions.

Jim

 

I have a 2001 E-350 Cargo van that runs on CNG only. I love it but recently had the check engine light go on. I am getting a p1151 code which is the opposite of a p1152. The p1151 is from a flat lined o2 sensor in bank 2 (drivers side). I replaced the o2 sensor and the problem remains. The CNG vans only have 2 o2 sensors. There is no o2 sensors after the cat. I am suspecting gummed up injectors on bank 2 or some type of air leak into bank 2 causing a lean reading on the bank 2 sensor.

The only problem with CNG is the lack of knowledge and information for the DIY owner.

I would guess you have/had leaky injectors, you make need to have the Computer Adaptives reset, you should also clean your MAF sensor. You can buy MAF sensor fluid from checker auto.

 

And the reason for the lack of knowlege and info is due to the fact that the DYI owners are not certified to touch CNG and LPG systems.

 

changed out the original spark plugs (138K on them) and it is running perfect!!

 

I am also not certified to change spark plugs ....

 

LOL, after looking at a few of these factory systems, I told my friend that she can take her's in to get new plugs. No way am I touching it.

 

Hey tomerloy, i have a cng crown vic throwign the exact same code and almost exact same mileage.

did you really need the 02 sensor or was the code being thrown due to a bad spark plug (and the 02 sensor couldn't correct the mixture)?

should i start with plugs first or do both plugs and 02 sensor??

thanks -- please let me know

 

Sorry about the delayed response....The 02's were probably fine...it was the plugs..

Always start with the plugs...(cheaper)

 

Thanks. I did plugs and they were badly needed, 4 new 02 sensors that probably were not, and still had the problem. turns out that the fuel injectors get clogged on cng vehicles due to the oil on the cng stations compressors and not having liquid fuel flowing through them.

Here is a TSB that outlines the issues and how to remedy it. It worked great and if you are having any of the above problems, change your plugs and do this procedure - this will take care of it:

https://www.ford-trucks.com/tsb/fulltext/show_article.php?tsb=*03-20-6

good luck!

 

That's funny I have been trying to figure out how to turn off the CNG so I can replace the filter element and do a injector cleaning on a 98 E-350. The problem is I cant find a shut of valve anywhere. Apparently the e-350 and e-250 are set up different from the Crown Vic.

I hope I don't have to burn off all the CNG to reduce the pressure. If so I will be trailering these vans to refill them.