I built my fuel system to run EFI with a pump in the tank but now I am going to run a carburetor for a few years. Do I have to take the pump out of the tank to run the engines mechanical pump?
Or replace the in tank pump with one that outputs only 5 psi. Or a standard fuel pickup in tank and an inline electric pump, limited to about 5 psi output, or as you suggested, the engine mounted mechanical pump. Anyone have additional ideas?
I'd probably pull the EFI pump out, clean and dry it and put it away for the time being, and replace it with a low pressure electric pump, either internal or external.
Engine mechanical pump should be able to pull through the elec pump in the tank. But why have that extra restriction. Just take out the elec pump and save for later; and add whatever extension to get the fuel pickup to the bottom of the tank.
Is it a modern factory tank unit? these have the pump, gauge, surge bowl all included, or an aftermarket pump only? The factory electric fuel pump (probably applies to all EFI pumps) is a small gear type of animal, there might be too much restriction for the gas to flow.. If it's using a factory type, remove the pump and add a pickup pipe with the original strainer, this will still allow the gauge unit to operate.
I run my flathead powered roadster with an tank EFI pump with three 97's. I run a carburetor "return" style regulator to knock the pressure down to 4 PSI and another Holley regulator to further reduce it to 2.5 psi before it hits the carbs (as I could not find a return style regulator that will reduce the pressure to 1-4 psi in one piece). Runs great and has for a few years now. Anything is possible with the correct engineering and money.
I agree with Billy. Put a regulator in that lowers the pressure down to what your carb needs and let the remainder return back to the tank, shouldn't be a problem. Pump will run cool and your carb will get what it needs, then if you decide to go back to EFI, just swap out the regulator with a higher PSI unit.
What pressure regulator are you guys using. I have a EFI return style regulator that goes down to 30. I had it installed but removed it yesterday. If I put that back in and add a non return 1-8 pressure regulator after it before the carburetor will that cure my problem? I don’t know exactly what pump I have Its a tanks inc unit that replaces the original. I got the whole setup at a swap meet in 2019.
There are some in tank pumps designed to work with carbs, they were used in old Rivieras and Vegas....if the pump you have is the same style that was used in GM EFI tanks, then you might be able to subs***ute the pump for a low pressure one like this https://www.rockauto.com/en/moreinfo.php?pk=3626784&cc=1062010&pt=6256&jsn=907 but that would require taking it apart and looking.
I think I answered my own question. I will put the return style fuel pressure regulator back in and feed that to a 1-8 pound non return regulator that way when I get my dream engine I only have to remove the 1-8 regulator to run the EFI. Much easier than messing around in the tank Thanks to Bandit Billy for putting the idea in my head
Make sure its a EFI regulator that will adjust down to 0-7 ish psi @ outlet ,,, These will not be a cheap regulator,, $200 plus part . You can also dump / byp*** fuel off pump with a open line right back to the tank with a ""Y"" so you will have a lower pressure to control @ carb ,, Make sure you LOOK @ spec, & ALSO if your return line is to small Smaller then inside of 3/8s or # 6 , #8 is more efficient, Not all return @ tank are free flowing , Including fittings , it can stack restrict & will still have High press , I switch between Carb & EFI & MFI quite frequently ,
Been there. In tank for EFI, into a carb. I was running a McCulloch, blowing thru an AFB, so I used the boost reference. Not cheap, just works. Might be somewhat like what Bandit’s got? Seems to me mine with a spring change would do a throttle body or maybe a port EFI also. Don’t remember. https://aeromotiveinc.com/product/a1000-4-port-carbureted-byp***-regulator/
The Jalopy Journal
