Throttle Body injection operation?

one more question while we are on the subject...   Can I use the carter electric (low pressure) fuel pump to run a carburetor? or do I need to get the mechanical fuel pump?

DD,   Thanks for the response

on my boat, there are two fuel lines at the top of the tank, one for supply (attached to the dip tube, anti siphon valve) the other is what I assumed to be a return line.   I could tell there was fuel flow from the pump to the inlet of the TBI unit, as I was getting fuel out of the schraeder valve when I checked the pressure. when I pushed the center of the Schrader, fuel would come out, turn the key, the pumps would run and pressure would resume.

your assumption of my symptoms is correct... I am not getting anything out of the injectors. since everything on this engine is an unknown to me at this point, I am going to put on the carburetor I have and try that way.   I am not sure that going any further with this TBI system is going to be advantageous to me.   

I did find this in my search...   
Holley made a "Pro-Jection" tbi system that resembles the system on my boat.    Here is a link to the manual

Holley TBI manual

I don't think the injectors are clicking at all.     Should they be clicking during cranking?   I assume that they should show some indication of spraying fuel during cranking?, but there is no indication of that currently. Can I isolate injectors vs. wiring/computer issues by manually firing the injectors?   if so, how would I do that? voltage?

My boat is a 1994, with the Pro-boss set up a(high output 351w with gt40 heads, Protec ign & TBI) .   This was factory for my boat/engine combination and from what I understand was phased out in 1995 as it was problematic.    The Holley set up is identical in looks to mine, except for the ECU.   

I do have a local dealer, If I decide to pursue FI at a later date, I will have it checked out.   My current goal is to make it run so I can determine whether the block is cracked or not, so I want to get it running with as little expense as possible.   As of last night, I have the TBI removed and a carb installed, but have yet to run a inlet line from the pump.    I think the carter high volume pump is going to be OK to supply the carburetor(4-7PSI) but I haven't checked it yet. I need to put a gauge on it before connecting to the carb.   I'll probably order a mechanical pump in the next week or so to give it a complete factory carburetor set up.   With cold weather knocking on my door, I need to winterize soon, so I need to get all my troubleshooting done ASAP.    

Good info!   thanks Zach I'll bend up a fuel line for it and give the carb a shot.   I too would see the cool factor of keeping the injection, but don't want to spend extra money to find out that the ECU is the problem, then be down the carburetor road anyway.

On a TBI set up the injectors flow continuously just as a carb flows fuel continuously. On port type systems tthere is a cam or crank sensor that sends info to the ECU to fire the appropriate injector at the right time along with controlling spark. Most TBI systems run 45lbs of fuel pressure for the injectors to open properly. In a TBI the ECU adjusts the fuel flow whereas in a carb the amount of air passing through the venturi regulates the amount of fuel. So a couple routine things to do first, you said you had fuel so check for adequate pressure,also check for spark. Also check all fuses, relays and connections. Also on fuel injection systems there should be a return line.
I know this is overly simplified but all TBI is is a high tech electronic carb. Aside from the common checks to make one failure point in the system that will cause it to not run is the throttle position sensor. The O2 sensor with cause it to run poorly but still run, the same with the temp and knock sensors.