Yeah problem with continuity is that when your circuit checking you have to disconnect the circuit on both ends to get correct readings. Specially when checking power supply wires for shorts to ground because if it is still connected it will find a way to ground through other components.

High ohm reading could indicate a poor or open connection and low could indicate a shorted or full connection.

As for the CAN bus system im not 100% sure. Your definitly correct that on most other vehicles 60ohms or close to would indicate a good system as they have more than 1 module on the bus requiring 2 terminating resistors. But the Combilift only has 1 module on the bus and isnt communicating to anything unless you have an lcd display like on the newer units. Units with 1 module on the bus usually have the second terminating resistor built into the diag connector or the dongle itself that you use to connect to it. So your reading could possibly be ok and seeing as how your were able to communicate with it I wouldnt think there would be an issue.

I found my Impco training for the S3000 ECM and theres some good theory of operation in it. Im assuming this would be the correct system thats on your CB but if it doesnt sound right I apologize.

This is saying
Key On Engine Off.
A) The key switch signal to the ECU (12v) causes the ECU to energize the Power Latch Relay which supplies power to the ECU, Electronic Throttle Body and the various input sensors. The Power Latch Relay stays powered as long as the Key is On.
B) When the key is first turned on the Power relay is also energized supplying power to the Fuel Shut-off Solenoid, Ignition Coil, Fuel Injectors and O2 Sensor. If the engine is not being cranked, after 2 seconds the Power relay will be turned off. The relay will be turned on again if an engine RPM signal is sensed.
Note: Turning the key off and on again quickly will not result in another 2 seconds of Power relay. Only after the key has been off for 20 seconds and then turned on again will the 2 seconds of power been seen again.

The document also refers to the Power relay as the Fuel pump relay later on for some reason.

Following this schematic battery power is supplied to pins 30 and 86 of the Power relay. ECM supplies ground to pin 85. Ground wire from ecm also has a diode in line somewhere in the harness. If you were jumping this then you should have had power supplied to the 20amp power fuse. If you do have power on the fuse but not at your ignition coil or injectors yellow power wire you very well could have an issue with the fuse box or wiring there after.

Since you can communicate with the ecm and crank i wouldnt think there would be an issue with other fuses or relays at this time.

It also goes on to say you can check the ecms control over the injectors with a test light while cranking or a noid light if you had pwer supplied to them. It would be interesting to know if the injector ground and ignition mofule was being pulsed by the ecm during cranking as well indicating it wanting to fire and just missing power to the system.

Engine wouldn't run when relay was bypassed, I was able to get fuel to push through the system but no injector power to get it to the combustion chamber, no spark to ignite it, Monday I'm going to look over my grounds, check my fuse block (because as mentioned before I was able to get it to run before by swapping the fuses, maybe an internal short by a broken block) I also need to mention, I know stated before that getting continuity wasn't a "tried and true" way of finding the problem but I did want to throw out that I'm getting continuity from power to ground in that relay fuse block side, it's a high number I believe 36ohms, this isn't good correct? Or not supposed to have continuity between the 2 since they aren't necessarily tied to the same wire, including the high ohms could indicate a short possibly? Also would like to mention when ohming out the Hi and Lo can systems (like on most cars or Toyota forklifts for example, you check the ohms between the 2 and if it's 60ohms it means your computing systems are good, 120ohms would indicate a bad controller or ECU etc) I got about 135 ohms when I checked between the 2, asked around to some guys I work with and they said it's not for sure bad because they aren't sure how CombiLifts computer systems run, even the Combi Lift tech said he wasn't to sure as he's never checked them that way before

When you bypassed the power relay did the engine run?

This will suck if it does end up being a bad ecm thats not available. Ive never had much luck with sending controllers and ecms out for repair.

From everything you said it sounds like powers not going to be your issue for the most part and need to focus on the whole ground side. Engine grounds, ecm grounds and go from there i would even bypass that stupid battery disconnect and run my own fresh ground wires for the ecm to rule those out as well.

I hope your able to find somthing, all this work you definitly need a win!

Just read your reply deeper, yes I have tried jumping it to no avail, that's what the Combi support tech told me to do, I do seem to get power to everything, even power at the fuse and relays constantly, I do need to check ground because combi tech said the ECU may not be supplying a solid ground (faulty ECU) hoping that's not the case seeing as they can't be replaced and only shipped out the repair, that's last resort I want to make sure it's 100 percent the problem instead of throwing money at a problem I could've fixed for free

I appreciate the ideas, Monday I return to work I'll post some before and after pics as to show what I was working with and progress on this job, this job was literally scrap to a functioning unit, everything has been over looked, replaced, and or installed, started with bare frame and motor to a working lift, I do have a spare harness and fuse block I can look over, I have the schematics I will share incase someone else is in need of it and maybe someone can help point me in the right direction if I'm over looking something major, to answer your question, when running the tests I did have oil pressure, unit will run without the oil pressure wire hooked up (found that out because someone seemed to have cut the wire to mess with me) truck would die after not sensing the oil pressure after about 10-15 seconds, and I would read RPMs and Crank variables on the graph

Sounds like youve done quite alot of digging and replacing already. Just wanted to throw some Ideas your way.

Im more fimiliar with the PSI system then Impco but i think alot of the system is similar.

When you had the impco diag software hooked up to do the injector kill test was the ecm recieving a crank, cam and oil pressure signal?

Continuity checks are ok but not great. Continuity can check out good even on a bad wire thats not capable of handling a load.

Id have to look at my schematic but pretty sure the power relay should supply power to your ignition and fuel system components.

On the PSI system when the key was turned on the ecm would cycle the power relay on for approximatly 2 seconds to do a check then turn it off again waiting for crank sensor signal and oil switch to confirm engine rotation before turning it back on again.

Have you tried bypassing the power relay with a jumper from terminal 30 to 87? Have you checked the relay terminals to see if your missing control ground from ecm or power input?

Have all ecm powers, grounds and key switch signals been checked not just for continuity but loaded voltage drop aswell?

When it was running and you said injector 4 had intermittent power did u confirm voltage was steady on the other 3 injectors? Or trace the wire back to the splice for the 4 injectors?

Sounds like you may even have multiple issues not just one. And like I said i do have info on these but havnt looked at one in a little while. There not very common around where I live.

If I think about it later when Im near my stuff ill take a look to see if I can think of anything else

So there was a "updated " fuse block assembly and or recalled block for these issues sometime ago. Block assembly would be cracked and or faulty from unknown causes. Also there was the distribution board below the dash that has had numerous issues with corrosion on them and or plug issues. Sounds like you have a relay issue stopping power. Which runs through the above mentioned components. I've replaced fuse blocks and these boards before and comes back to bite you again. So. Also make sure your direction lever is also in good shape. Moisture on these machines isn't very friendly. A lot of open connections exposed to even humidity and moisture.
Even the key switches used are not very reliable.