I posted this on LS1tech site, but haven't gotten any replies yet. Maybe some of the truck guys can help.

I have a 5.3 from an 04 Tahoe and just discovered it is a flex-fuel motor, which means it has a return fuel system. I am installing the motor in a 55 Chevy truck. I am using a fuel pump from a 2000 LS1 Firebird, which has an internal regulator. My plan was to route a line from the pump to a filter, then to the motor. Before the filter I would loop the fuel line back to the return connection on the pump. This would maintain the fuel pressure.

Can I just plug the return rail at the motor and treat it as a return less system, or do I have to run the return line. Would rather not replace the fuel rail with a return less one.

Any help would be appreciated.

 

Personally, Id just get the correct rails. The return style is wanted by people like me who are retrofitting a ls to a older truck already setup for return.

It would be just as easy to use the correct fuel pump for the motor. Id imagine it shouldnt be hard to sell your extra parts either way.

 

Return systems are better in my opinion but a lot of guys run return less without issues. I would get a different pump and run an external regulator with a return line. Then you will never have to touch it again. Or you could just swap the fuel rail which is simple enough. Either way, I would change parts so your systems components work correctly with each other.

 

The LS1 pump does not have an internal regulator.
There is always a return.
In the case of the f body, the return is near the tank.
In the case of the truck, the return is in the tank.
You can not just dead head a pump.

If you meant to say that you have a pump assembly that has a bypass, then capping off the rail, you should be ok.
(I prefer to regulate flow at the rail and running a return)

Can u get pics of the pump you have? Again, that is my main concern because there is no f body pump that I know that has a bypass. 4th gens had a return except it is under the car near the fuel filter.

 

Return style fuel style system that is regulated at the rail keeps the fuel pressure at the rail regulated better than a non-return system.

 

If running after market fuel rails, how do you utilize the factory fuel lines going to the tank?

 

Fuel line repair kit from parts store,so you will have 2 short sections of line to plug into the quick connects then the hard tube adapters from Summit to adapt to AN.

 

Would you happen to have a picture?