patooyee
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My fuel system starts with two in-tank pumps, both of which have a built-in check valve.
I only use one pump at a time, the other is just a spare, and I was told that the built in check valves are not robust enough to hold back full pressure and are just there to maintain prime, so each pump also has its own inline check valve that IS rated for full pressure to prevent one from pumping through the other when not in use. These check valves are in the fuel cell. Both pumps then tee together into one supply line that goes out the top of the tank and then through ANOTHER inline check valve before going through the rails and into the regulator. This check valve is redundant, left over from a previous pump setup.
The regulator is an Aeromotive with dual inlets, an outlet, and a a port for a gauge, which I am using for an in-cab gauge.
The fuel then returns to the tank.
When I first built this system everything worked fine. When I shut the pump off pressure would remain in the lines for almost an entire day. But about halfway through my first ride it suddenly started bleeding down very quickly after shutting the pump down. By the end of the ride pressure would drop to zero immediately after being shut down and the pump would then have to fill the lines again when starting back up every time.
While the rig runs there are no issues, pumps can maintain pressure just fine, plenty of power. There are no external fuel leaks, not even a fuel odor coming from anywhere. I have switched both pumps and it happens when using both of them.
I've had injectors stick open in the past that would make fuel pressure drop this fast. But every time they have filled the cylinders full of fuel causing the engine to lock up, destroy a starter when trying to start, or run extremely rich. None of that is happening now, as I said, engine is running perfectly.
For the pressure to be lost through the pressure line it would mean that the redundant inline check valve both in the line and at the pump as well as the internal pump check valve would all have to have failed. They were all new when installed, the ones in the tank are only a couple months old with maybe 6 hours of ride time total, the one in the line not much older than that. I would think the chances of all those valves failing would be near zilch.
My next thought is maybe the regulator is dumping pressure back to tank via the return line when it shouldn't be? But I would think if that was the case it would have issues maintaining the correct pressure?
I'm kind of at a loss as to where to start looking. Prefer not to just start tearing everything apart. Anyone seen this before or have a theory that I haven't covered? I'm afraid that making my pumps constantly re-prime like this is going to kill them sooner than later.
I only use one pump at a time, the other is just a spare, and I was told that the built in check valves are not robust enough to hold back full pressure and are just there to maintain prime, so each pump also has its own inline check valve that IS rated for full pressure to prevent one from pumping through the other when not in use. These check valves are in the fuel cell. Both pumps then tee together into one supply line that goes out the top of the tank and then through ANOTHER inline check valve before going through the rails and into the regulator. This check valve is redundant, left over from a previous pump setup.
The regulator is an Aeromotive with dual inlets, an outlet, and a a port for a gauge, which I am using for an in-cab gauge.
The fuel then returns to the tank.
When I first built this system everything worked fine. When I shut the pump off pressure would remain in the lines for almost an entire day. But about halfway through my first ride it suddenly started bleeding down very quickly after shutting the pump down. By the end of the ride pressure would drop to zero immediately after being shut down and the pump would then have to fill the lines again when starting back up every time.
While the rig runs there are no issues, pumps can maintain pressure just fine, plenty of power. There are no external fuel leaks, not even a fuel odor coming from anywhere. I have switched both pumps and it happens when using both of them.
I've had injectors stick open in the past that would make fuel pressure drop this fast. But every time they have filled the cylinders full of fuel causing the engine to lock up, destroy a starter when trying to start, or run extremely rich. None of that is happening now, as I said, engine is running perfectly.
For the pressure to be lost through the pressure line it would mean that the redundant inline check valve both in the line and at the pump as well as the internal pump check valve would all have to have failed. They were all new when installed, the ones in the tank are only a couple months old with maybe 6 hours of ride time total, the one in the line not much older than that. I would think the chances of all those valves failing would be near zilch.
My next thought is maybe the regulator is dumping pressure back to tank via the return line when it shouldn't be? But I would think if that was the case it would have issues maintaining the correct pressure?
I'm kind of at a loss as to where to start looking. Prefer not to just start tearing everything apart. Anyone seen this before or have a theory that I haven't covered? I'm afraid that making my pumps constantly re-prime like this is going to kill them sooner than later.
