Do TJs have a clear flood mode?

Steel City 06

Steel City 06

TJ Expert
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I recently learned on some cars if you completely floor the gas pedal and then start it, the fuel injectors don't add any fuel and the engine just cranks. It's traditionally used to clear a flooded engine, though it can also be used for diagnostics (if you need to turn it over without starting).

Do TJs have this feature? Or am I going to start it at 5000 RPM?
 
I thought you couldn’t flood an engine that was fuel injected. Is that wrong?
 
This does not seem like a difficult thing to test. I suspect our Jeeps don't have the feature. Next time I do a hot start I'll test and report back if nobody else has. I'm sure you could flood the Jeep somehow, maybe a leaking injector or something?
 
Our engines have enough safeguards where flooding won't happen. It's a non-issue that used to be a common problem with carburetors. If flooding was a problem for even older technology FI systems I'm not aware of it.
 
Clear flood mode is often installed on a lot of fuel injected cars.

Google only brings up one claim that TJs (at least 2005) have clear flood mode, and it didn't seem confirmed.

An alternate to pulling the fuel pump relay would be to put the gas pedal to the floor while cranking as this is a clear flood mode or at least it is on my 2005-you can try it and verify on yours.

Here is a very basic description of clear flood mode:
https://www.ericthecarguy.com/a-flooded-engine/
 
I'm thinking it might be useful for when you're working on it and just need to turn it over.

Alternatively, perhaps it could be used in 4Low and 1st to move the vehicle a very small distance.

I'm not expecting a flooded engine, just curious if the TJs have this feature.
 
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Below is from the 2004 TJ operator manual, this might be what is being eluded to as far as a "Clear Flood Mode" it does not seem to turn off the injectors like many newer vehicles do. It is really the same procedure to clear an engine with a carburetor (for those of us who remember), which explains the second paragraph.

I do know that my 2013 Mustang GT, 2014 Mustang GT500, 2018 F150 (sold), 2019 F150, 2020 Expedition and 2016 JK do shut off the fuel if the accelerator is held to the floor while starting, but my 88 Bronco does not.

If Engine Fails to Start
If the engine fails to start after you have followed the
“Normal Starting” or “Extreme Cold Weather” procedures,
it may be flooded. Push the accelerator pedal all
the way to the floor and hold it there while cranking the
engine. This should clear any excess fuel in case the
engine is flooded.
If the engine has been flooded, it may start to run, but not
have enough power to continue running when the key is
released. If this occurs, continue cranking with the accelerator
pedal pushed all the way to the floor. Release the
accelerator pedal and the key once the engine is running
smoothly.
 
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If flooding was a problem for even older technology FI systems I'm not aware of it.
Click to expand...

The older "batch fired fuel injected" cars/trucks used to flood real easy (at least the Fords and GMs) when they had fuel related electrical problems back in the early 80's but I do not remember any of them having any type of "Clear Flood Mode" like the modern ones do now.
 
Jerry Bransford said:
Our engines have enough safeguards where flooding won't happen. It's a non-issue that used to be a common problem with carburetors. If flooding was a problem for even older technology FI systems I'm not aware of it.
Click to expand...

Hi. I'm reading this forum because I have the strangest problem with my 1999 jeep Sahara 4.0 L five speed.

It cold starts in the garage like a champ every time! (so there goes the leaky fuel pump check valve theory.)

Then, totally predictively when I get where I'm going and I've parked the jeep, then return to the jeep 15, 20, 30 minutes later... crank, no start. I floor the gas pedal like I would in a carbureted car to clear a flooding situation and then it starts. You can smell raw fuel in the exhaust for a few seconds. By the way I added the silver fuel rail heat soak kit from DEI months ago. No change whatsoever.

Any ideas?
 
JPTJ said:
Hi. I'm reading this forum because I have the strangest problem with my 1999 jeep Sahara 4.0 L five speed.

It cold starts in the garage like a champ every time! (so there goes the leaky fuel pump check valve theory.)

Then, totally predictively when I get where I'm going and I've parked the jeep, then return to the jeep 15, 20, 30 minutes later... crank, no start. I floor the gas pedal like I would in a carbureted car to clear a flooding situation and then it starts. You can smell raw fuel in the exhaust for a few seconds. By the way I added the silver fuel rail heat soak kit from DEI months ago. No change whatsoever.

Any ideas?
Click to expand...

The check valve issue occurs on a hot start, not a cold start. Common misconception. Cycle the key 4-5 times to prime the system on a hot start. If it starts fine, the check valve is bad. It is very possible the valve is bad and stuck open.
 
No kidding! I never would've guessed that. Thank you for the information. I guess I'll start looking around for a fuel pressure gauge to screw into the fuel rail. I think I saw something on YouTube where a guy put an in-line check valve outside of the tank because of ease. Ever had any experience with that?
 
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Man these pop-ups are intense! lol
I was trying to write that the injectors leaking makes sense because the smell of raw fuel is very strong when it finally restarts after holding the pedal to the floor, which increases airflow I guess. Is there anyway to check those rather than just pulling them out and replacing them? Or is it just the O-rings? That DI kit I bought came with new O-rings but I did not install them. Nor did I remove the injectors. I just cut the foil and bent it around the injectors.
 
JPTJ said:
No kidding! I never would've guessed that. Thank you for the information. I guess I'll start looking around for a fuel pressure gauge to screw into the fuel rail. I think I saw something on YouTube where a guy put an in-line check valve outside of the tank because of ease. Ever had any experience with that?
Click to expand...

Yup. Racetronix has adapters.

IMG20240330184511.jpg


-Mac
 
JPTJ said:
Thanks Mac. 50-ish PSI. Is that running or just key on priming? Or both,


very nice! Thank you!
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Both. Interestingly enough the gauge drops to zero after a bit but I get an instant start. I blame the next to cheapest BrutePower fuel pump I could buy at $58. I spent more on the adapter and fuel pressure gauge than I did on the pump.

-Mac
 
macleanflood said:
Both. Interestingly enough the gauge drops to zero after a bit but I get an instant start. I blame the next to cheapest BrutePower fuel pump I could buy at $58. I spent more on the adapter and fuel pressure gauge than I did on the pump.

-Mac
Click to expand...

But you had to pull the tank...oof. I sure don't want to do that! lol
 
JPTJ said:
But you had to pull the tank...oof. I sure don't want to do that! lol
Click to expand...

I did not have to pull the tank to install the gauge on the fuel rail.

You can pull the tank out with little drama in less than an hour with a little (or a lot as in my case) practice. Assuming it's the pump.

-Mac
 
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