View Full Version : fuel pump cut relay?

01-30-2002, 02:30 PM
what the hell does this do?
84 rx7 12a, im trying to rewire it and I come across this in scematic in my shop manual, do I need a "fuel pump cut relay"?, also where does the fuel bypass at the carb return to?

Daryl Brightwell
ITA Mazda #90

01-30-2002, 10:00 PM

"What the Hell does this do?" not sure, cut fuel pump under certain conditions?

"Do I need it?" NO...I ran two cars for 5 seasons without it...no problems.

"return line"...back to the stock fuel tank.

Understand, I don't have knowledge of the all the little nit-picky rules in IT..so I am not sure, and wouldn't be suprised if you can't remove it!

Festus E. Simkins
01-31-2002, 11:45 AM
The cutoff is in case of a roll over it cuts the fuel pump off.

Return line is to gas tank.

I run a 1st gen RX-7

I have a fuel cell and deleted the cutoff switch. I use a return line.

There is some discussion about the need of a return line in a race car. I think it helps keep constant pressure at the carb. I run 21/2 lbs pressure. I use a 1/2" fuel line to the carb and a 3/8 return to the cell. Never had a problem.

Drive well.

01-31-2002, 02:25 PM
I have a fuel cell so I will have to add another fitting on the cell, but that shouldnt be too hard.

01-31-2002, 06:58 PM
Actually the fuel cut relay cuts off the fuel pump if the bowl in the carb gets two full. If fuel backs up the float raises and triggers the relay. A side benefit I believe is if the car is on its top, gravity trips the switch cutting off the fuel pump.

I'm not sure you want or need to bypass it.

The only way I know about it I got a deal on my current IT chassis because the former owner couldn't figure out why it wouldn't start. The carb had become so dirty from sitting while the 'for sale' sign was on it that for some reason the switch stuck in the open position. I spent a lot of time scutinizing the shop manual to figure that one out.