Regulator before or after the rails?
Thread Starter
Instructor
Joined: Jul 1999
Posts: 165
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From: Vernon Hills IL
Regulator before or after the rails?
Upgrading my fuel system. Twin in tank pump setup, one switch from a Hobbs switch.
This keeps haunting me because I keep seeing different setups...
I am running my fuel line into a Y block, then one line to each rail.
The regulator goes after the rails right? Not before. I think I keep seeing some folks with the regulator before going into the rails. I would think it should be after to build pressure in the rails.
Someone please set me straight.
THanks,
Jeff
This keeps haunting me because I keep seeing different setups...
I am running my fuel line into a Y block, then one line to each rail.
The regulator goes after the rails right? Not before. I think I keep seeing some folks with the regulator before going into the rails. I would think it should be after to build pressure in the rails.
Someone please set me straight.
THanks,
Jeff
Race Director
Joined: Apr 2007
Posts: 11,152
Likes: 890
From: South Western Ontario
After lets the pump purge the air out of the rails. This is the time tested way it's usually done. Your Y block to each rail and then Y blocking the other end together again for the regulator allows for good fuel with little pressure drop in the fuel rails, especially compared to something like a U that goes through one rail then the next rail.
If you run the regulator before then the fuel to the rails "deadheads" so there is no place for the air to go as the rails first fills. Not a big deal but it's probably going to require some bleeding to let the air out first run.
I believe new cars are either running a pump that is voltage controlled or a return-less regulator to maintain pressure without the return tank flow. I think to avoid stirring up the tank and causing more fuel vapor that can be lost to the air. But, this usually isn't a concern in performance applications.
Peter
If you run the regulator before then the fuel to the rails "deadheads" so there is no place for the air to go as the rails first fills. Not a big deal but it's probably going to require some bleeding to let the air out first run.
I believe new cars are either running a pump that is voltage controlled or a return-less regulator to maintain pressure without the return tank flow. I think to avoid stirring up the tank and causing more fuel vapor that can be lost to the air. But, this usually isn't a concern in performance applications.
Peter
