Fuel Cutoff Switch (Anti-Flood) and Unflooding Procedures

Many older 2nd gen rx-7s suffer from a condition referred to as flooding. This happens as an engine gets worn out, its compression drops lower and lower, and it becomes hard to start especially when warm(short trips).Even though there may not necessarily be an excess amount of fuel in the combustion chamber, the condition of hard starting or no starting on a rotary is referred to as flooding. Note that though it is possible to flood any rotary, only the 2nd generation suffers from this chronic problem in general. Also note that the 89-91(series 5) rx-7s have a built-in flood protection system and do not flood as much as the earlier 86-88 models. The series 5 flood protection is very easy to use: floor the gas pedal while cranking the car over to CUT fuel to the engine and thereby unflood it(if lightly flooded). IT is possible to flood a series 5 to the extent it requires an unflooding procedure outlined below.

Note that fresh rebuilds(using old rotor housings with imperfect sealing surfaces) often have very low compression in the beginning(under 1500 miles) and may require unflooding until compression builds up within spec. Use these same procedures in this case. Installation of a fuel cut switch is also recommended for the breakin period.

Unflooding a lightly flooded 2gen - Phase1:
Unflooding a lightly flooded 2gen - Phase2:
86-88 NON TURBO models can utilize a single vacuum hose to inject the atf/oil:
87-91 TURBO Engines Method:
Fuel cut off switch:

Unflooding a lightly flooded 2gen - Phase1:

Remember that you don't need to do this step for an 89-91, just floor the gas while cranking to duplicate this effect. The below instructions are for 86-88s.

1) raise hood 2) remove underhood fuseblock cover 3) remove EGI fuse closest to engine 4) Crank the car over for 5-10 seconds, 2-3 times. Car may start and die, or might sputter as if to start. 5) Replace the egi fuse 6) Quickly get back inside the car and start it up. IF usually helps to floor the gas at this time to let more air into the engine.

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Unflooding a lightly flooded 2gen - Phase2:

There are a few different ways to go about this, depending on which model and year of car you have. The tried and true method entails the following:

1) remove BOTH EGI fuses closest to engine in fusebox 2) remove plugwires and lower plugs 3) crank the car over 5-10 seconds with plugs out to expel extra fuel 4) Obtain some ATF(automatic trans. Fluid) or motor oil along with a method to inject it to the lower plugholes of both rotors. This will mix with the excess fuel, rebuild compression momentarily, and help the car restart. I use a hand oil pump available at autozone, which fits in a gallon jug. You can also use a small oil can with a vacuum hose, or a funnel with a long hose. Be sure to get enough in the first time, you don't want to have to keep repeating this step. You cannot really put too much atf in, as you cant hydrolock a rotary. The excess will just get shot out the exhaust port. About 1/2 cup per rotor should be more than enough. 5) Dry plugs and clean them with a wire brush, or replace them if you feel they're heavily fouled, or if this procedure doesnt work the first time. 6)   Replace plugs and wires. 7)   Replace fuses. 8) Crank car to start. Floor the gas when doing so. Expect a lot of smoke. Hold the rpm's up a bit for the first minute or so until it smooths out and runs more normally.

This is the hard way to do the job, but it will always work. Depending on your year and model it may be possible to use an easier method.

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86-88 NON TURBO models can utilize a single vacuum hose to inject the atf/oil:

In fact there are 2 locations to do so. You can not use a funnel in these methods, you will need a pump to force fluid in.

Method 1: 1) Locate the upper intake manifold, the ribbed aluminum casting that has 13B injection printed on it. 2) On the front end of that intake are 3 vacuum hoses. One is larger than the other 2, the larger one is on top. 3) Remove the larger one. You're going to pump the atf/oil into this HOSE slowly. This hose splits into 4, and leads to all the oil injectors on the block, which inject directly into each combustion chamber. Doing this will not interfere with the oiling duties of the oil injectors later. 4) Pump slowly when doing this, as these are small orifices youre pushing though. 5) 3-4 pumps should do it. Replace the hose and start the car. Method 2: 1) On the same upper intake, on the drivers side, there is a large vacuum hose(about 1") leading in below the BAC. Above that is a small, 3mm vacuum hose. 2) Remove it, you can pump into this nipple, which will squirt atf/oil into both primary intake runners evenly, though this method might require more atf to be injectors(to run down into the engine) and longer to work(to allow time to traverse the length of the intake).

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87-91 TURBO Engines Method:

1) Locate the upper intake manifold, passenger side, and the BAC valve (round piece mounted on its side). 2) Above the BAC is a ? shaped hose. Remove it. 3) You can pump into this hose(downward into the upper intake/BAC) which is evenly divided between both primary intake runners, and it will run quickly into each chamber. 4-5 pumps will be enough. You can also use a funnel and hose for this one, as there is no restriction in this hole.

Method for 89-91 nonturbo engines has not yet been found to be practical. IT is best to do the sparkplug method unless you feel like loosening the upper intake manifold and pumping directly into the intake runners.

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Fuel cut off switch:

The "band aid" cure for cars which flood consistently is to install a toggle switch which will control the fuel pump. Note that the only cures for consistent flooding are cleaning/rebuilding injectors, rebuilding the engine, or finishing rebuild breakin. I like to install my cutoff switch right behind the keyhole in the lower column surround, but anywhere within easy reach will work. I use a toggle switch available at radio shack for about 2 dollar, called a rocker switch. IT is solid black, very slimline(maximum protrusion 1/8") and fits perfectly. You can use any toggle switch however.

1) Obtain the following: 2 prong, 2 position toggle switch, at least 2 feet length of 16-14 gauge wire, 2 female speaker terminal connectors(quick connect), 2 wire taps(vampire taps) and wire crimpers/strippers. Vampire taps join one wire beside another, when a metal strip gets pushed down connecting the 2 wires. A clean way to connect 2 wires. 2) Remove column cover and install the toggle switch in its position(or wherever else you want). 3) Locate the fuelpump relay under the dash. Located between the radio and the steering column, it is a black relay with a white, 5 wire plug. 4) Cut the fuelpump control wire: of the 5 wire plug, cut the middle wire of the 5. 5) Run wires from the toggle switch to each of the ends you just cut and connect them all. Which wire goes to which end does not matter, there is no polarity here, only continuity. 6)   Put everything back together. Your switch is now installed. 7)   To operate it, figure out which way is on and which is off. I like to orient off downward. 8)   With the car running, turn the key off normally. Remove your key, and leave the switch alone. 9)   When restarting, flip switch OFF, insert key, floor throttle, crank car, and it will likely start up. IMMEDIATELY as soon as the tach needle passes the 750rpm line flip the switch on. IF you're quick enough the engine will stay running.