Looks like Mazda built in an anti-flood proceedure on the series 5 cars. Has anyone ever tried this to see if it works? This is from page F2-44 out of the 1989 FSM!

"To clean out excess fuel in cylinders (yes it says cylinders, very funny), as in case of engine flooding, no fuel is injected when the accelerator pedal is held fully depressed while cranking the engine."

 

Ive heard that the S5 come stock with a anti-flood device. That when you step on the gas while starting it up that it cuts the fuel pump off like it would do when you remove the EGI fuse. Not sure where I heard this from but I don't know. Anybody know if this is true????

kleach

 

i heard this also, if it floods you can push the gas pedal all the way to the floor and it cuts off the pump to get it unflooded

 

I can't say that I have, but I know the series 5's have a sort of thing where you press the gas pedal all the way down when you start if the car floods.

 

Tried to attach "the proof" but failed. I'll try again...

 

Yes It's true. I have had many s5's and it does work. You can however, flood the car bad enough to still need to atf it in order to get it running again, but its pretty rare. S5's dont flood NEARLY as much as s4's.

 

Ok, I know this is going to sound wierd, but every (and I mean every) time my RX7 flooded, that's exactly how I started it. Held my foot to the floor and cranked, eventually it fired. That saved me about 5 times that I can recall.

But mines an 88

PaulC

 

Same here. This worked on both my 88 and 87.

 

BUT..
does anyone know WHY this was done this way?

There were so many ways that they could have implemented this anti-flood method..


Here's why..

Once, all cars were carburated.
It became comman practice that if you flooded your carburetted car, that you held the accellerator to the floor and cranked it.

Remember that?

RX-7s flood mainly becuase of short operation times where you drive the car a block or otherwise runn the engine for a short time and then turn it off.

The various temperature sensors are still registering "cold start" or just plain "cold" and screw the mixture up to WAAAY to rich.

this is okay if the engine is running, but not okay if you shut the car off DURING this "rich run" time.

Well, just in case someone flooded the RX-7 (as it was prone to do under the above conditions) , the engineers decided to emulate the anti-flood procedure of years gone by.

After all they could reliably know (thanks to the throttle position sensor) wher the pedal was in space at any time.

In duplicating the un-flood procedure of older carburetted cars, they allowed the RX-7 ECU to behave just as a carburetted car would under the same conditions.

SO, even if you never read the manual, or were told about the unflood procedure, owners, by sheer HABIT, might unflood their cars as they always had.

Pedal to the floor, and the start the car.

They simply turn off the fuel injectors, (not the fuel pump) if the ignition is activated at wide open throttle.

It even goes so far as to RE-ACTIVATE the injectors if you let off the pedal just bit.

However, it will not turn the injectors back off if you return the pedal to the floor during the same cranking attempt.

So, the successful un-flood procedure for both carburetted cars AND fuel injected RX-7s is:

Peadl to the floor, crank the car for a few seconds, let off the pedal, (either while cranking or stopping in between) and then start the car as normal.

A stroke of genius actually.
(And a bit of luck)

 

It works. I've flooded my engine ONCE and I just held it down and cranked (man I wasn't happy hearing all that cranking... also I was parked nose down so I think it took longer than usual...) but started up like a charm after a bit.

Pretty Schweet, if you ask me.

-ZenFox

 

Same here.

Dan

 

Yes its not just series 5 cars but in the owners manuals of series 4 cars as well.

 

I seem to need to start my car like it has a carburator. I crank it at give it a little gas at just the right time or it won't start. I'm also running rich as hell? anyone know if these might be related?

 

I dont think that the S4 cars can do this.
I would like to see the manual for a s4 car that shows this.

As far as I know, this is a S5-S6 thing only.


VEARRG:
i bet that if yo upulled codes on your car (assuming its a 89-91 car) that you would see that a thermosensor is possibly fasling or not hooked up.

Pull the codes and let me know.
The method for pulling codes is all over this forum.

search for ECU, code, "check engine" etc.

 

Typpically the W.O.T. start serves two purposes:

1) Reduces engine vacuum to the absolute minimum so that no additional fuel is drawn in from the fuel system. This works well on the carb and on the leaky fuel injector.

2) Allows the engine to pass the maximum amount of air through the motor (which aids in passing excess fuel) with the least amount of resistance. As a side benefit it also puts a little less work on the starter so it can spin the motor a bit faster which gets oil pressure up sooner. This of course helps us out on our washed out rotary seals.

So when Mazda is nice enough to put a zero in the fuel map at the 100% TPS, 0 RPM site we've got an effective anti-flood proceedure.

Funny I didn't see anything in the 1987 FSM about it...

 

The owners manual for my 87TII describes a similar procedure...

 

Page 3.3 in the 88 owners manual, engine flooded
if the engine is hot and won't start, it may be flooded.
1. Depress the accelerator pedal to the floor and hold it.
2. Turn the ignition key to the "START" position and hold it.
3. When the engine starts, and runs smoothly release the ignition key and accelerator pedal.

Caution Do not keep the starter engaged for more than 10 seconds. If the engine stalles or falters in starting, wait 5 to 10 seconds before reenggaging the starter. Otherwise it may be damaged.

Note
for easier starting, the headlights should be off.

This should be found in all the other series 4 manuals as well, I just don't have copies handy.

 

see:



I personally don't see why people don't believe this... it was on the 84-85 GSL-SE as well.

 

I just use my fuel cut off switch

 

My s5 has flooded maybe 3 times. Cranking at WOT worked twice. I had to pull the ECU fuse once.

 

The question of the day is weather or not S4 and previous cars (GSL-SE) actually shut down the injectors or not when this proceedure is performed. That is when it's most effective. I'd also like to know when the injectors are allowed to come back on in such a scenario. I would guess somewhere around 500RPM or so.

 

i pull the ecu fuse also

 

i never flooded yet

 

Apparently ALL 2nd gen cars have this WOT start anti-flood procedure.

(If what Im reading here is right.)

Therefore, there is NO, and I mean -NO- need for fuel cutoff switch as I have always thought.

this holds true ONLY if the WOT start procedure exists on all 2nd gen cars.

We always had a fuel cut switch.

(And its apparently not as simple as a "0" in the fuel map.)

It only woorks ONCE at initial start.

If it was in the fuel map, then it would happen each time you pressed the pedal to the floor.

 

No, actually; I do think it is in the map, that a hold signal is created on anything over 2 seconds of full throttle while cranking.

I am sure the TPS helps detect this, and that would allow for the initial "pump" of the accelerator pedal suggested in cold temp starting.

But yes we have always had a fuel cutoff switch built into the ECU, too bad the owners manuals that describe it are not considered mandatory reading and ownership.