EFI and fuel line routing diagram.

[Bulldoglover]

I purchased a 74 Bronco with EFI where the previous owner installed EFI. He installed what looks like 6 way solenoid valve mounted on the frame and he bypassed the 3 way selector valve for the main and aux, tank. When you stomp down on the gas petal, it's acting like the engine is starving for fuel and does not have the Power I think it should have.. Does anybody know if f I can rerouted the fuel lines to go back through the 3 way tank selector valve with the new EFI system.? Can I install check valves in the main and aux. tank lines to insure there is no back pressure to the tanks? I do know there is supposed to be a fill line and And a vent line for both tanks or is it a recirc line? Previous owner said sometimes the aux tank or main rank (depends on what tank was fuller..would pressurize and spit fuel out of the fill cap.... I really don't understand that statement on why it's could do that. And Lastly could I have a bad fuel Module? If so how can I check it to see if it's bad? There is a plug in on top of it,, possibly for a diagnostic tool. Thanks I'd appreciate any help and if anybody could email me a fuel line diagram using both tanks with the EFI system that would be great. Again that's for any input I can send photos if it would help.

 

[Timmy390]

The stock 3 way is designed for low pressure and does not have a return line. EFI systems are high pressure and most require a return line. I'm guessing the 6 port valve the PO installed is the one BC sells and is designed for an EFI system with dual tanks. It includes return ports for each tank.

I run only off my main tank. Aux is installed but i don't use it.

What most people do is run off the main tank only and setup a "transfer" pump to move fuel from the Aux tank to the main as needed. Not a fan of this myself but i seems to serve those who set it up that way well.

The 74 tanks should have a vent unless they've been replaced with an earlier year tank. I'm guessing the vapor recovery system is long gone? Mine is. I have the parts in the attic but have not replaced them. My system work well so I don't fix what isn't broken.

Tim

 

[Steve83]

You're guessing blindly that the fuel lines have ANYTHING to do with the symptom. It's NOT likely that they do. If you don't understand a system - especially one as dangerous as the fuel lines - leave it alone. Post several pics of it, and we can help you figure it out, but don't start tampering with it.

"EFI" is pretty vague. Is it a later factory Ford EFI engine? Or is it some aftermarket EFI system slapped onto the old engine? The more we know about it, the more likely we can help you diagnose the symptom. Post pics of that, too. Read the first several posts in this thread:
https://www.supermotors.net/forums/thid-5972-how-do-i-post-pictures-sounds-and-or-videos

 

[Bulldoglover]

Thanks Timmy & Steve. It is an Aftermarket EFI system installed on an older 302 Ford. At present after reading your comments I'm going to leave it alone. Its running good but so like Timmy said leave it. Again Thanks

 

[Cortez]

For what it’s worth, I used the Pollak 6 port fuel selector valve with my Fitech fuel injection system and it worked fine on a 351w, it should not restrict flow. It’s definitely tricky to install the selector valve as any inline fuel pump needs to be within about 18 inches of the tank to draw fuel. Maybe if your pump is far away from the tank it’s struggling to get fuel but there again it should only be on start up when it needs fuel to pump properly. If the pump is not full of fuel you can usually hear cavitation...the pump may run louder until it gets fuel in it...then quiets down when it has fuel pumping through it. If you hear cavitation at the same time you feel it’s starving for fuel then something could be going on there.

 

[ntsqd]

If you are cavitating the fuel pump then it's likely not long for this world. The fuel flowing thru them is what keeps them cool.

Also, if you are cavitating the fuel pump then you're likely to have vapor lock between the pump and the tank.

I'm of the opinion that two tanks require two pumps. Can set up a relay to switch the pump power with the selector valve's switch.

Long ago I read that transfer systems in gasoline fueled vehicles is illegal at the Fed level. Law supposedly came about because of the early 70's fuel crunch where people were rigging up such systems and burnt down a few vehicles in the process. I've no idea if true, but it sure seems possible and even likely. If you do build a transfer system you need to build it in a way that prevents brain fade from causing a problem.

 

[Steve83]

...illegal at the Fed level. ... I've no idea if true...

If you feel like researching it, this is one I found when researching power windows:
http://www.ecfr.gov/cgi-bin/text-idx?SID=63cea3b1f6d6b52110798d9edd22e76c&node=sp49.6.565.b&rgn=div6
So it's a starting point to find federal vehicle laws.

 

[Bulldoglover]

No cavitation in the fuel pump, the pump is closer to the aux tank than the rear tank.