Running car w/ carb and MS II hooked up?

[dustbull70]

Hello everyone,
I am putting a MS II into my 1970 Duster with port injection. I Have just finished building my MS II board and everything checks out with the tests in the manual. The biggest issue i have with this conversion is that the duster is my only means of transportation, so i need to make this conversion go as smooth as possible, with as little down time as i can. I am wondering if i can wire the relay board, intsall an electric fuel pump, hook up my MAP, IAT, WBO2, and CLT to the MS II and drive around with the carburetor still for a while (Basically have everything ready to go, just swap out the intake for injectors/throttle body later...maybe even get some data to speed the tuning process in this time).

I dont know how it would harm anything, i just want some reassurance that this will not damage the MS board, and that with all these "strange" readings coming into the MS that the fuel pump will still run normally ( i havnt looked yet at the circuit for the fuel pump to the relay board/MS II)...Thanks everyone for the help!

[kjones6039]

It ought to work fine, except, you certainly can not run the carb with your high pressure pump! You will need to leave your stock pump in place until you are ready to convert.

Otherwise, it will not damage your board!

Ken

[dustbull70]

Great! Thanks for your help! ...I do intend on running the electric pump, but it will be to a return style efi regulator, then thru another temporary cheap regulator to get the pressure from 20 to 5-7psi.

[jcarruthers]

Yup that'll work great, it's how I had mine set up for the same reasons as you. I had it running sensors, then running ignition and then a couple of months later got all the injection sorted.

A nice way of doing it as you can check everything is working well.

[Six_Shooter]

I would install all of the components that can be installed that won't effect the way the engine runs. Basically mount as much as possible, leaving the current carb and dizzy alone. Then in a weekend that you can set aside, start Friday night after work, and get the rest of the conversion done by Saturday afternoon, or Sunday morning, leaving Sunday to do a drivability tune.

You can cut the harness to length, and add the connectors where they will need to be, while leaving the car the way it is, by just simply laying the harness in the bay, attached to the relay board. You could possibly even install things like the coolant sensor while still running on the carb. If you're planning an EDIS ignition, you can get that all prepped, including the trigger wheel with little to no down time before you're ready to switch over. The fuel pump can be mounted and the fuel lines ran, while leaving the original system in place, just cap both ends so no dirt gets in.

If you're running MPFI, you'll want to run higher fuel pressure than 20 PSIG. Most MPFI systems run at around 44 PSIG, some newer systems run as high as 55 PSIG.

[trakkies]

Do you have a second inlet manifold complete with injectors and TBs, etc?

I did when doing my conversion and set it all up in the workshop before swapping to the engine. Got the tach signal from a stim. You'll also need a much bigger power supply since you're driving the real injectors, or use a car battery. But don't run it for long with no fuel going through the injectors.