Running engine on a stand - electrical questions...

[misterW]

I built a stand to run a 3.0 vulcan on. I'm planning on putting a 99 engine into my 91, so once I combined engine parts on the engine, I wanted to make sure it was working before I put it in the vehicle. I've seen a few videos of people running engines on stands, but I have never done it and had some questions on getting the engine going. Fuel will be pressurized with an air compressor and put into the rail via an injector cleaning device. I can attach my radiator to the stand for cooling. I'll rig up some type of temporary exhaust. My question is about the electrical components though. I'm assuming I'll have to have current going through my Power supply box so it can get to the computer. The power supply box is on a separate harness though (not the engine harness). What do people usually do? Take that entire harness that includes the power supply out for the stand as well? I'd rather not do that, since I'm going to have to put that back in the truck after. Should I find a salvage yard power supply and harness and just cut off the parts I need? How is this usually done?

 

[Shran]

I can't imagine most people do this for a one off project... there's really no point in doing it if you don't have every sensor hooked up and working and can bring the engine up to operating temp. So you would need a donor engine harness, computer, etc and would need to figure out how to power everything and make it start and run.

If you are really committed to doing this, I would find a junker '91 with a 3.0 engine and remove the entire engine bay and dash wiring harnesses and clip out the unnecessary parts. This is a pretty easy thing to do with old carbureted engines or some diesels but modern fuel injected engines are a whole different deal.

I would also suggest using either a complete fuel tank with pump, or a sending unit stuck into a gas can instead of your compressed air idea as well.

 

[RonD]

I assume you are using the 1991 TFI with distributor setup on the 1999 3.0l

It is a stand alone spark setup as far as start up and RPM spark advance
You just need 12v for coil and TFI module, also ground, and it will provide spark, assuming distributor is timed

So you really just need fuel to start it and keep it running, you can do that manually with a spray bottle of gasoline, not ether, at least not ether long term

If you want to test the injectors then yes you will need the computer hooked up, via wiring harness
You really just need 12v and ground to computer, and its hook up to TFI to time injectors
It will set all sorts of codes, lol, but it will run the injectors
1991 uses a Return fuel system so you will need a Return line on the FPR(fuel pressure regulator) that runs to a "bucket" to collect the gasoline the fuel system isn't using when primed and then when running
No sensors, except TFI modules timing signal, are needed for startup and running


But if you just want to hear if engine runs with no "noises" then you don't need the injectors or computer
............but, don't have the fan attached to engine, to noisy, and not needed, AND make sure exhaust is vented out far away because it will also be NOISY!, and of course can kill you in an enclosed space,
Also plug up ALL vacuum ports

You want QUIET to hear any problems

 

[Ramcharger90]

Honestly it's simpler to put it in.....

 

[misterW]

I agree it is more straightforward to put it in, but I've had weird issues with this truck that may involve harness problems, and I think it would be helpful to isolate the problems I've had if I run it outside the truck where I can more easily control all the variables. Plus, I've always thought it would be cool to be able to run an engine outside first to make sure everything is good, and it's been a fun project to work on.