I recently installed a return style fuel system: Fore hat, twin walbro 342's, -10 supply and -8 return lines, Fore rails and regulator. After tuning, I datalogged the fuel pressure and it is solid through all rpms. When starting the car you have to crank on it longer than normal to get it to start. One thing I noticed when I shut the car off is the fuel pressure drops to zero in a few seconds. I thought the walbro pumps had a one way check valve to hold fuel pressure when you shut the car off? Is this normal or do I gave a problem?
Do I have a (fuel)problem??
- Thread starter bd93cobra
- Start date
it's a return style system. the return line flows right back into the tank. the fuel pressure regulator does just that.........regulates fuel pressure. When you shut the car off and there is no longer any vac on the regulator and no pressure going to it the gauge will drop to zero.
No problem at all
No problem. Yeah it takes a minute to wrap your head around the idea when you have been used to a returnless system. A returnless system with a pprv will hold pressure for a long time.
My fox body has a factory return style system. So the walbro pumps don't have a built in anti-siphon valve?
not sure about an anti-siphon valve built into the pump. Will have to do a little research on that
also not sure what all is involved in a factory fox fuel system but as far as what you are seeing with your return system on the cobra it is normal. My triple pump return setup does the same exact thing.
Do you notice that you have to crank on it a little longer for it to start? How's the 2.9 working out?
stock fox body setup has a check valve in the system. you can add one to our setup if you want(converted return style). Aeromotive makes a nice one. I wouldn't sit there and let the car keep cranking until it starts.
OP, I don't know how you have your pumps wired, but mine are wired so I use the green/yellow from FPDM harness as my trigger to each relay for my pumps. I turn the key to the on position, it activates the relays and then sends power to the pumps. So my pumps are on full force when I turn the key to the on position and they stay that way. So I just turn the key to on position and wait about 5-10 sec for the lines to build pressure and then I start the car.
OP, I don't know how you have your pumps wired, but mine are wired so I use the green/yellow from FPDM harness as my trigger to each relay for my pumps. I turn the key to the on position, it activates the relays and then sends power to the pumps. So my pumps are on full force when I turn the key to the on position and they stay that way. So I just turn the key to on position and wait about 5-10 sec for the lines to build pressure and then I start the car.
That's how I have my pumps wire, wire from CCRM triggers the relays that give full power to my pumps.
ok, then don't sit there and crank until it starts. just let it prime and fill the lines. I can actually hear a tone change with the lines filling and then going back to the tank. so even though your pressure gauge says whatever you have the regulator set at, it doesn't mean the lines are full and car ready to start. give it a few to fill up.
This is the correct way to start any fuel injected vehicle anyway. I have found that every vehicle I have tried this on starts easier if you just turn the key on for a few seconds to prime the pumps before engaging the starter. In the old days of carbs, you would usually have to prime the car by pumping the gas pedal a couple of times prior to starting. This even easier, but still a similar principle. Car equipped with check valves, and pprv type devices just have them to save the starter from excessive wear from ignorant people that think they should just turn the key and crank the crap out of it until it starts.:nonono:
That is funny, because once you get used to doing it, it really does become second nature.:lol:
Like others have said I just turn the key on when I get in the car. buckle up while the system is priming and then it fires right up. With 3 pumps my system is pushing more volume so I would guess it happens a little faster than your 2 pump setup.
Users who are viewing this thread
