Ha Edward we are just in the talks to convert it to the CA100 carb and wire throttle cable. Great minds think alike.

this truck, when equipped with the correct mixer, uses a diaphragm that has a different PN than your generic ca50 mixer diaphragm, and actually has a thicker washer under the "bullet" which keeps the "bullet" from sticking in the mixer housing. since it seems your mixer is one with an adjusted screw, rather than a plug and Allen head screw behind the plug, as the correct one would have, most bets are off.
AS you are not in the USA, and as such not covered under the rules of the US Federal EPA, have you considered converting this truck to one with a throttle cable linkage?

does this ECU have the hose running to it from the mixer for the MAP sensor?

Hey Swoop

We did a complete LPG tune up ,cleaned carb and installed new diaphragm.

Hours 7950

good deal prentice
i still think you may have an issue with the mixer since you cannot get the goal on your dwell.
Just out of curiosity how many hours are on the engine?

Oh Edward i just caught the 'tier 1' thing...
hehe... thier all Tier 1's man chuckles

:o)

Well, it's fixed........kind of. Not the ECU. Changed the fuel regulator solenoid ( 3 vac line - red and white wire) Dwell still high 75-80%. but it runs and has good power.

Bugs me it's not 10 out of 10 but a 8.5 is a good start

Thanks for the great information

May have sourced it to the ECU - Can these be reprogrammed or bought a reasonable price

prenticelift at gmail dot com

when you say 'carb mixture screw' are you speaking of the set screw behind the small expansion plug on the side of the mixer?
Yes there is a small expansion plug you have to remove to get to the dwell set screw.

IF this is where you are trying to adjust and still cannot achieve your setting you may want to look at the mixer diaphram, make sure its clean and in good condition. Also make sure all your vacum lines are connected and in good condition. And as edward mentioned, that fuel valve is working properly, it should have a chatter or buzz when it is operating, it may start and stop the buzzing but when the engine is running it should be making that noise.

looks good, we will let you know our fix. Thanks again for the great support

As to maladies that can afflict the vacuum advance, I have had a case on a 4G63 where the vacuum advance diaphragm chamber on the atmosphere side of the diaphragm got so packed with dirt/lint entering where the actuator comes out of the vacuum advance metal shell that the vacuum advance could not move at all.
On that model the actuator opening was oriented skyward, just right for gravity to do the rest.

Should anyone have any thing on this system, they would need you to either add your e-mail to your profile, or send them an e-mail.
Referring to the dwell, are you sure the manual says "should be set" or does it say "should read"? In this case dwell is the % of on time the pulse happens for the fuel valve, which will/should vary with all sorts of information, as it is the thing that gets changed in "closed loop" running, and the timing is a pretty straight forward vac advance the same as 4g6* motors had been using since the early 80s.
The MIL light will come on if they let the truck idle for more than about 4 min, and as far as I know, the "solution" is to tell the operator to not leave it running and not driving for more than a couple of minutes.
The K in the model number does not indicate the drive by wire models, I know the emissions system from the 'D' in the serial number series.
Have you checked the timing with a timing light?, and checked to see that the vac advance really is working? I have had a few where the port inside the throttle body for the vac advance was plugged up, and cleaning with a very small welding tip cleaner was a good fix. my bet from your description is either the distributor vac advance hose in the wrong spot on the throttle body or a stuck weight on the advance plate, or too long a screw in the dist. catching the pickup plate keeping it from moving. It may also be related to where the pickup for the computer's temp sensor is located, if you add something as thick as an extra nut you will change the reading considerably, I know even an added flat washer will change what temp the computer sees by about 5 degrees..

Great ,we appreciate your detailed report. The truck runs fine. The problem is the operator had an older wire cable throttle ( GC25 ) in the past, they switched him over to the newer unit ( GC25K) and there complaint is - first thing in the morning ( cold , Canada eh ) they start the unit and the unit has lack of power and low throttle response, the Red triangle with exclamation comes on intermittent and the driver shuts down the unit, We advised them to start the truck and allow a warm up period to get the engine to operating temperature. After a long period of complaining from the operator, we now have the unit in our shop we hooked up PC and found the high DWELL the manual says good running operation should be set to 40-50% but will readjust with temp and atmospheric pressure from 20-80%.

this is the head scratch-er. we can remove the idle screw from the carb completely and the unit runs fine ?????

We will review your comments and triple check everything. Do you or anyone else have any literature on this??

Thanks

This is called the s15g system by the folks who used to be at MCFA when this truck was new, and in spite of what swoop keeps calling 'tier 1', this is the tier 1 MCFA product, and was made/sold in 2003 only.
"dwell" on this machine refers to the fuel trim solenoid valve (red and white wires, sticking up on the thing mounted beside the LPG regulator), and while it is good to be able to see for some troubleshooting, is not really something to be adjusted. What is the symptom you are trying to fix? [?who told you to try for a dwell setting?]
The controls on this machine are not good for idling more than about 4 min with out getting the MIL light on. and the main adjustment made with the laptop is the accel pot.
The hook up of the vac lines can sometimes be confusing, and cause problems. there is what looks like a "tee" that is not a "tee" and miss connection of the lines can cause it to run bad, Some early units had an elbow that had a 'bb' sized ball inside on the vac hose right at the metal section of the large air intake line over the valve cover, that can get stuck and cause intermittent shutoff or rough running.
NEVER test the red and white wires on the fuel trim control valve with a meter or test light, you may well let the smoke out of the little black box with next key cycle, and is a pulsed signal.
Does this unit's little computer box have only white potting that you see when you look into the hole where you plug the computer? if so you will need to insure the vac hose is what appears to be unreasonably long. if you can see transistors rather than just plastic, the vac line connection is a plug and does not require a particular length hose. the engineers used the hose length to calibrate a vac drop, and lots of folks looked at the hose and said it must be too long, so they shortened it. Barber Coleman made the original system, which had been in use for years on stationary power systems for air compressors, but as they run at 1 speed and load most of the time, there were some problems with operations that the operator had a clamp and "bounced" control handle more than 3 times to hydraulic stall while driving, and Barber Coleman went out of business, so the computer had to be redesigned and sourced from a different vendor. The vac hose on ones with the white plastic potting should be the lowest hanging point on the truck.
As this unit has only a 1 wire O2 sensor (not heated) this truck does not go into "closed loop" until the engine is at normal operational temp, and the temp sensor to the controller is not the same temp sensor as the dash gauge sees, but is 2 black wires on a lug mounted to one of the manifold studs, and may be confused with a ground lead.
btw, if this truck had the correct carb, you would have a plug and not a screw to set.
I would also note that on this truck one of the more common missed connections is on the throttle body, where there are 2 vac line connections, make sure the one closer to the engine goes to the computer, the one further away from the manifold is where the connection to the distributor vac advance goes.