Mazda B series EFI conversion tip

The second gen RX7 electric in tank pumps are a drop in replacement for the pickup tube/ level sender assembly in 86-93 mazda trucks. They have a better fuel level sender, and even an extra wire you can connect to a low fuel warning light/led in the dash. I just verified this with a 1990 RX7 NA fuel pump assembly.

This is a good alternative to an inline fuel pump, lower cost and factory fit. Just pull the pickup tube from your stock tank and drop in the RX unit.

so does that mean this would work for a fuel cell? if so what would you do with the mechanical fuel pump on the head?

good to know man. you said the FI tanks have special baffles. will it hurt the performance having an in tank pump in the carb'd tanks? since those dont really have the baffles...what exactly do these baffles on the FI tanks do?

the baffles keep the gas around the pickup, EFI needs a constant supply to maintain pressure. Gas sloshes under accel, decel and cornering, so on like 1/4 tank you could "run out" of gas momentarily.

It would work in a fuel cell if you were switching to EFI, madlowmazda did just that. I just left my mech pump on the head, but I'll make a block off when I a) get my plasma (next week) and b) get my new driveway poured (in two months)! I'm so excited!

this is good info Russ- keep it flowin man!

ok thats all fine and dandy, but what about a return line, if your disconnecting the line from the fuel pump and hooking it directly to the carb, what do you do with the return line, and arent you going to have higher pressure then also

Return line would be coming right off you new fuel rail for your fuel injectors, whatever type of setup you have. The fuel line return doesn't have to be extremely high pressure line. You would just use the stock mazda steel lines on the truck that run between the fuel tank and the engine bay. There already is a fuel feed, return and vent line present. Just use high pressure rubber fuel injection line from your pump to the fuel rail with fuel injection clamps, and you are good to go.

Originally posted by im2lo4ya

if you're disconnecting the line from the fuel pump and hooking it directly to the carb,

there is no carb in an EFI system. Thats why the title of the thread is EFI conversion tip.

Like Jim says, the return line exists on both carbureted and EFI systems, and neither is high pressure. The RX7 in tank pump also has a return. If you switchover to EFI, you dont need any part of the factory mechanica pump any longer. You can disconnect it and leave it on the cylinder head with no ill effects, it is not chain or sprocket driven, only a flapper that rides on an eccentric on the factory cam; or you can remove it and make a block off plate.



Sorry for the confusion.

Russ- you can get a fuel pump block off plate from a 12 valve f2 motor- probe/ 626/ mx-6. I know for sure you can get on off the 8 valve efi 626. I got one if you want it!

Originally posted by MadLowMazda



Russ- you can get a fuel pump block off plate from a 12 valve f2 motor- probe/ 626/ mx-6. I know for sure you can get on off the 8 valve efi 626. I got one if you want it!

garrr I never thought of that! I'll dig one up though, no need for shipping it in from St Louis.