its the same pump as the pump thats in the vst pump, just doesnt have to be submerged like the vst...

Those pumps are not designed to suction that well, that is likely your issue. I have a spare VST complete if you need it, or you should add a boost pump to the set up you have, maybe the mechanical that supplied the VST? That is how the 500 EFI works.

This engine has a host of sensors that control virtually ever aspect of it's operation. I have the manual for mine and in the trouble shooting section first thing it always says "Did you run a diagnostic scan for codes" I am in the process of finding a dealer qualified to work on mine. I 'm begining to except the fact that I can't fix this one myself.

Guys Please Help!!!!

Here is the non-scan diagnosis for the sensor system. Let me know what else you need.

Fixx
 

electric fuel pumps are designed to push fuel not suck! with it being mounted @ the transom that's a long distance for it to suck fuel then pressurize it for the 50psi fuel pressure that the engine probably needs. it could run @ 45 psi, like griff said get the rite fuel pump and mount it as close to the tank as possible and as low as possible so the pump don't have to work as hard to maintain the fuel pressure needed..i would go with a aeromotive,make sure you put a filter in front of the fuel pump,you don't want to jam it up if theirs crud in the fuel tank..

I have the mechanical pump hooked up to push the fuel to the fuel pump itself.

That sounds weird... What size line are running from the mech pump to the elec. pump? It sounds like you might be starving the electric pump for VOLUME of fuel. That big line going into the elec. pump is needed to supply the pump with enough fuel.

Aeromotive recommends putting the pump as close to the gas tank as possible. Do you have access to the gas thank? If you're hell-bent on running the elec. pump you might want to move it to the forward most position in the engine compartment, as low as possible, and mount it before the mech. pump.

That's how Merc does the HP500 EFI, mechanical pump pulls from the tank and feeds the pressure pump in the cool fuel box. If you read that manual page I posted it says the warning system will cut 4 cylinders at 2800 and then restart them at 1200.

Do you know what size line they use though? I can see it working if its a really big line... And, doesn't Merc use the fuel pump mounted on the raw water pump to do this, or is that just in the Gen V mech pump negation GM blocks that they use this in? If they always use that pump it seems like its a much heavier duty pump than the block mounted pump, but I could be wrong...

Maybe its just my experience with Aeromotive pumps and the volume of gas that they need (and big pick up tubes) that skew my thought process on this...