aceduecey

I have a 1985 rx7 which originally had a carburated 12A motor which has been replaced with a carburated 13B motor. The replacement was done by a previous owner.
I'm having some problems with fuel starvation and wondering if the fuel pump and fuel filter should have been replaced at the same time. Is the fuel pump for a 12A and 13B different? What about the fuel filter?
If so, is there any way, via a part number confirmation or identification, to know if this had already been done? If not, I'd appreciate any advice you could give me for a solution.

thx,
mike

3rd and final 7

iTrader: (9)

Why dont you take pictures of the fuel pump and filter, you can pictures from the back of the car.

85rotarypower

The fuel pump is lots different between the two. First off, the 13B in the 1st gens was a fuel injected engine, not carb. Its a high pressure pump. As for your issue, its probably the fact that the owner that did the swap used the stock 12A pump, which was barely enough for a stock 12A, let alone a 13B. If it is the 12A pump, throw a holley red pump with regulator in there and you'll be happy.

djessence

Hes asking how you can tell them apart because he is not sure what is no the car atm, because the engine swap was done by PO

Druken

The fuel pump for a 12A and 13B are completely different. If you noticed on all the models that have a 13B, the main fuel line increases in diameter thus requiring more fuel. The fuel filter is also different, the 12A is a low pressure filter while the 13B is a high pressure filter. The 13B requires the fuel to be pretty clean to allow flow through the injectors, while the 12A burns everything through the carb.
I don't want to give you my advice and have it ending up hurting you, but I would run a 13B fuel pump/filter but set the fuel pressure regulator to a bit higher than what the 12A requires. But you might want to wait for more replies.

gsl-se addict

iTrader: (3)

It also depends what carb is on the 13B (Weber, Holley, etc.). Some carbs like the fuel pressure to be higher (also need more flow) than what the stock 12A pump puts out. A pic of the current fuel pump and info about the engine/carb would help greatly in letting us help you figure out what you need.