I just bought a 1999 F350 with the v10 engine. It has a CNG system I would like to remove. The controller sasys technocarb efs 600. When I cut the power to it the truck cranks but does not fire. I dont see where any of the factory wires have been cut but they have been spliced onto. It lools like the fuel pump wire, fuel injector wires, and a coil wire have beenn splced onto by the engine and several more wires have beenspliced onto near the ECM. I would like to remove the CNG wiring harness but I am not sure if my ECM was reprogrammed to not start the engine if it doesnt see the CNG controller?

 

Did you do any googling for info?
I found this one
http://documents.rasoenterprises.com...LPG-Manual.pdf

In reading there manual there seems to be some type of scan tool
that is also used in the system. I did not see any reference to
reprograming the ECM/PCM. Lets hope that is not something that way
done. I do see where they cut the power to the injectors and fuel pump.
That would be one reason you get a no start.

I think if you work backwards of the install you will be able to remove
it and make the truck run like it was originally setup to.

Start with a step by step list of what your going to do. Even better would
be a check list.

I'll upload the PDF here so others can have access to it.
What I don't have for you and I am sorry I don't is a wiring diagram
for you year.

Please post back what you come up with.

Sean

 

So I got the CNG wiring harness removed and factory wiring reconnected and still my1999 f350 with v10 won't start. Do you think this means I need a new ecm?

 

Don't jump at the big $ just yet. What you need is a
wiring diagram for you year and a scanner that can
command actions. First would be to read any codes
and address them first. Also while you have it hooked
up look at what strategy is in the PCM/ECM. It may be just
that something is not getting a signal and the wire could
be well hidden.

Did I find the right diagram for the CND unit?

Was it running OK with the CNG system installed and was it dual fuel?

So first when you turn the key to "ON" does the fuel pump make any sounds?
Do you have any lights that are out when you first turn the key during the pre-start
lamp check?

AN OBD2 scan tool would help a lot at this point.

Ask in the forum if anyone can post an engine control wiring diagram for you year.

Before I would even thing about condemning the PCM/ECM there are quite a few things
to verify first so your not just throwing money at it and hope that something fixes it.


Sean

 

Yes it was running fine on gasoline before I removed CNG wiring. I do hear fuel pump run. All dash light s appear normal when cranking. What scan tool would you recommend??
Can you tell me how to check for 11 volts at the injectors? Could I pull a plug out and watch for spark? Thank you for the help.

 

Your not going to get any spark at the injector. (I would hope not).
You need a Voltmeter and some care. You don't want to short the
connectors out and kill the PCM/ECM. You should see 12 on one side
of each injector plug.

On Spark
If this engine has plug wires you can use a timing light to check for
spark by just hooking it up like normal. Then you know if you have spark.
If it has the COP units I am not up on how to check for spark on them.

With the age you could use one of the older Snap-on MT-2500 Scanners.
I don't know if one of the newer ELM bluetooth/smartphone type would give what you
need. It might but I would be guessing. The https://www.autoenginuity.com/
most likely would. I don't think that the cheep code readers you can pick
up at the auto stores would do much.

I'll take some time today and read the install guide and see if I can
give a better idea later today.

Sean

 

Yeah it has the cop. So I should put one lead on one of pins in the injector connector and the other one to ground? Do I have to be cranking engine to see voltage?

 

I think you can just do KOEO. But after looking at the diagram
that is where I think your problem may be.

Be careful and don't cram the probe tip onto the connector.
It will stretch the socket so that the pin won't make a good
contact later. Go from the back side.

Sean

 

I did a KOEO injector voltage test and didnt get anything....do you think my ecm needs to be reprogrammed?

 

You most likely still have a cut wire somewhere
in that section of the system or a dead relay.

Look at the diagram that was posted here
https://www.ford-trucks.com/forums/1...g-diagram.html
the 3rd one down at the bottom is the injectors. See the point where they
all come to one splice? That wire color says it RED. It goes up to the left
side to pin #6 You should have 12V there. From reading the installation instructions
they cut that wire at some point. If you spliced it check you splice to make sure it't
not bad.


Sean

 

The wires that were cut that I reconnected was a red with white trace and a red with a black trace and a yellow with a green trace and a gray the other three were sistered onto and I cut it off a couple inches from the end and put a dab of liquid electrical tape on the cut. How do I check for 12 volt at the #6 pin...from the backside?

 

Yes, That way you don't open the socket.


Sean