Do you happen to know where those wires are grounded in my case?

Quote:

The black green striped wire that you show in your photo is a body ground.

this wire is fitted to a stud, right in front of the battery; the only other wire on this stud runs to the neg. battery terminal.
Would you be able to get me any other directions to look at, to run the engine on gas again?
Cor

 

Can you tell me if you have one or two batteries?

 

Just one, Subford, right behind the driverside headlight.

 

Driver's side? That's weird. My 87 E150 has the starter battery on the passenger side and a deep cycle on the driver's side. Actually I don't see why they can't be switched around except that the very thicl cable to the starter solenoid would have to be exceptionally long.

 

I need a little more information here.
Is this a duel fuel truck, does it run on both gas and LPG?
I see in the LPG conversion kits that they replace the injectors with LPG
injectors and it looks like they do not use most of the sensors anymore.
They do not use the EEC (PCM) at all and use a new control module for the timing and so on.
Fill me in a little more so I know what you have.

 

Yes

Quote:

I see in the LPG conversion kits that they replace the injectors with LPG
injectors and it looks like they do not use most of the sensors anymore.
They do not use the EEC (PCM) at all and use a new control module for the timing and so on.
Fill me in a little more so I know what you have.

In this case the conversion is quite simple: on gas, the entire truck system is totally original;

on LPG, one red wire to the computer, which is wire on pin #23 or 22 on the 60 or so pin connector to the engine is cut by a relay. This is to disable the injection system.
Another relay then provides power to open the LPG solenoid valves.
The LPG system :the pressure reducer opens under engine vacuum, and propane is supplied thru 2 mixers in the inlethoses, just before the throttle body. Hence the propane mix is vacuum dependant.
Finally, there is a small electronic unit fitted, called a "oxygen sensor simulator" to satisfy the computer that all is well when running on propane.
This unit is interrupting a thin gray w. l.blue stripe wire, which runs in a harness just above the battery.
The computer is used, but not in full; which part, that is beyond me. In any case timing and all that comes from the computer, even the fuel pump is not disconnected, that is how I know the pressures that the pump can genrate.

In conclusion,the conversion, as far as the gasoline system is concerned is nothing more than interrupting one red wire to the computer at the multi pin engine connector, and the installation of the oxygen symulator.
Note, that this is a professional installation, in a country, where a large proportion of gas engines is converted to LPG, simply because LPG is 1/3 of the price of gas......It is this popular here that LPG can be filled up at ANY gas station.
I tell this as I feel that any reason for my troubles is not in the conversion.
Thanks for any assistance, but if you have more questions, I am more than happy to oblige.
Cor

 

Dannym, I believe that all this was changed with the introduction of the newer model in 1992; mine is a 1993, see below: the starter solenoid is also right in front of the battery





In this last picture can the LPG pressure reducer be seem with the shut off solenoid valve. A battery would never fit here in this model.
Cor

 

I think that is the ground you have there and are taking about above on the stud.
Pin 22 is the fuel pump relay wire that is grounded in side the EEC (PCM). So breaking this wire will turn off the fuel to the engine. You should have no pressure at the fuel manifold while running on LPG with this wire broken.
Pin 23 is the knock sensor.
If you lessen to the injectors you can tell if they are working or not.
Also I would check that fuel pressure again in the gas mode.

 

It looks like I have not been clear enough:
I have no problem while running on LPG. The fuelpump continues to run, whether on propane or gas, but the injection does not work when on LPG.

When selecting 'gas' , then crank the engine, the injectors can be heared ticking; this was also confirmed by the Ford technician.
Als I verified this myself in another way: pressure in the manifold, then briefly applying voltage to one injector, and the pressure drops, as long as you energize the injector; thus, the injector opens and injects the gas.

In my original quote of your reply to 'nukeday', I put the question, where the ground wires to the computor #40 and #60 terminals could be found, as you said that the ones in my vehicle are not the ones I should be looking for in this modelyear.
So, where could I find the location of the ground of computerwires #40 and #60?
Hope this explains my question better,
Thanks,
Cor

 

As I was saying in my last post, I think that #40 and 60 are grounded through the Black green wire at the stud. If pin #40 & #60 were not grounded I do not think it would run on LP. The prints calls out a black/white for 93 F series and I was hoping the E series was the same, but I guess not. The E series seems to lag behind the F series in changes.

I know you said that the fuel pump runs on LP or Gas but what I was saying if your device opens the wire going to pin 22 then your fuel pump should stop.

Puting voltage on an injector should not do anything as all injectors should have power on them at all times, the PCM (EEC) provieds the ground to open the injector.

If they are ticking then they are wroking and have power on them and the PCM is grounding them.

 

Again I need to explain further:

I pulled the electrical connector from the injector, grounded one side and applied 12 volt to the other, so I was opening 1 injector at one time, and had the rest of the system isolated from that injector.
Otherwise, I now fully understand your earlier response
Cor

 

Here is a diagram of a stock 1993 F series Fuel System, yours should be the same but the wire colors may be wrong.

 

I have now exactly worked out which wire has been interrupted in order to cut off the gasoline operation:it is red wire 361, where it enters the multi-pin connector C121 for the engine.

I have looked this up in the schematics on the Ford CD I have, and come to the conclusion, that this not only interrupts power to the injectors, but due to the location, also interrupts power to the Idle Air Control, the EGR solenoid, the Secondary air injection bypass solenoid, Secondary air injection diverter solenoid and the canister purge solenoid.
There is a jumper directly to the IAC, so this one works on LPG and on gasoline.
So the entire computer is powered as normally, it is just the injectors and some accessories which are cut off during propane use.
As said earlier, there is a oxygen sensor simulator fitted in a gray/ light blue wire.
I have traced this to be wire to pin 29 of the computer, for the Heated Oxygen Sensor Imput, circuit 74.
By the way, I have now checked the pin out and wire colors on the schematic for the PCM, and find that also the Ford CD for this vehicle and year do state that wire 40 and 60 both are black/white, while in fact one is black and the other black/green. (see earlier pictures.)
So there are some discepancies here too.
Anyway, this was not the reason for not running on gas, and I seem to be back to square one.
Cor

 

Do you have one or two gas tanks?

 

Just one
Cor