Starting a Mazda RX-8 with a flooded engine

October 12, 2010 · Posted in Transport 

Mazda RX-8

Mazda RX-8

A few weeks ago, I made the mistake of moving my RX-8 a short distance and didn’t allow the engine to warm up before switching it off. It’s well-known that this can lead to a flooded engine and this time was no different. :-( I knew it was a mistake, but I was in a hurry!

I’ve only had this happen once before and, as then, I couldn’t get the engine restarted using the manufacturer’s technique of fully depressing the throttle (should cut the fuel), cranking the engine for 10 seconds (should clear the flood) and then cranking as normal. Having tried this a couple of times, I soon ran the battery flat and so had to recharge it overnight.

Next day, I tried the tips from this excellent blog post. It describes how to unplug the air pump and remove the fuel pump fuse to assist with starting. I tried this but again failed, mainly due to lack of charge in the battery even though it was fully recharged. The same technique was used by the RAC chap who got me going the first time this happened – it took him about 20 minutes and of course he had access to a much better power source on his van.

Now out of options, I called the AA. The chap they sent out took a rather different approach which I’ll attempt to describe here in case anyone would like to try it:

RX-8 fuel pump cover under seat

RX-8 fuel pump cover under seat

1. Remove the nearside rear seat base cover. The lower seat cushion simply pulls up (see comment 57 from KenF below).

RX-8 fuel pump cover without screws

RX-8 fuel pump cover without screws

2. This reveals an access panel which is held in place by 4 sheet metal screws. Remove these screws and the panel.

Underneath RX-8 fuel pump cover

Underneath RX-8 fuel pump cover

3. There is a single electrical connector (black plug with 3 cables connected to it) on the pump assembly that provides power to the fuel pump and readings from the left-side tank level sensor. Take a moment to learn how to disconnect and reconnect this connector.

4. If possible, connect an additional power source to the battery (another battery or another car via jump leads).

5. Position yourself in the driver’s seat with your left hand stretched behind you (assuming you have a right-hand drive vehicle) ready to connect/disconnect the fuel pump. Keep it in the disconnected position.

6. Apply around 1/3 throttle on the accelerator pedal. Use your right hand to turn the ignition key.

7. The engine will turn but not start. After around 10 seconds, connect the fuel pump for a few seconds then disconnect.

8. You may need to repeat this a few times. Don’t crank for more than about 30 seconds at a time though to save your starter motor!

9. After a few tries, hopefully you’ll hear the engine getting close to starting. The point of connecting and disconnecting is that you are trying to clear the engine and then reconnect at just the right time to get the fuel pumping again (see Andy’s comment, 8 below).

The AA chap said that using this technique he can usually get RX-8s restarted in around half the time it takes using the fuse removal, etc. Apparently he learnt this from a chance conversation with an engineer from Mazda. I suspect it’s the sort of thing you need to try a few times to get it right, but it certainly seems to offer more control over the process as you can access and change all inputs at the same time (fuel pump, throttle and ignition).

Let me know if you try it. As always though, it’s at your own risk – I don’t want any repair bills for a knackered fuel pump or catalytic converter :-)

If you leave a comment below, it would be great if you could add which country you are in, there are quite a few here already!


218 Responses to “Starting a Mazda RX-8 with a flooded engine”

  1. Seán on October 7th, 2015 17:37

    Waow … never seen as many positive comments! Well done Spinage!

    I’ve just had my 8 delivered back from the bodybody shop after quite a bit of work, looks amazing but won’t friggin start!

    The body shop left it on my drive, obviously started it, drove it off the lorry and parked on my drive and switched it off! …

    Just been looking all over YouTube for a fix, just about to try this now as I’ve tried everything else …

    I’ll report back on my success! :-)

  2. Seán on October 8th, 2015 16:56

    Me again … as promised and just to let you know that after trying everything else … this got me going in under 20 mins …

    Spinage, I wish you had a donate button

    Legend! … and thank you!

  3. Seán on October 12th, 2015 21:26

    Happy 5th Anniversary!!!

    Spinage & his RX-8 “deflood” post … saving us 8 owners for 5 years!!!

    12 Oct 2010 – 12 Oct 2015


  4. Gerry g on December 19th, 2015 16:15

    My 04 RX-8 has connectors under both rear seats that look exactly the same. US model so steering wheel on the left. Am doing the fuse pull cranking now. On about 12-15th cycle. Nothing yet.

    So which side is the pump switch on?

  5. spinage on December 20th, 2015 18:07

    That’s great news Sean,thanks for getting back to us!

  6. spinage on December 20th, 2015 18:08

    Wow, hadn’t noticed that it’s been that long, thanks for spotting!

  7. spinage on December 20th, 2015 18:09

    Sorry Gerry, I only know that it’s on the left hand side on a righthand drive vehicle. Please let us know if you can confirm for a US model?

  8. Tim on January 3rd, 2016 23:20

    Took me about 30 mins to get our RX8 started with this method, I don’t think I would of managed without the jump leads and I agree with others that you do need to have faith and persevere. I’d moved our car and turned it off when still cold and then left it for about 10 days, wont do that again!
    Anyway, thanks for the info Spinage and happy new year to all other rotary fans worldwide.

  9. Kristof on January 9th, 2016 05:41

    Yesterday while i was out training, my neighbour’s battery had died, so my girlfriend wanted to help by jumpstarting him with our ’04 RX-8. (wich has been outside for a day at 6°C.
    They connected jumpleads, she turned on the engine, his car started and she turned the RX straight off (i recon when its still ideling at 2200 revvs)
    When we wanted to use it 4 houres later, no ignition, and the starter appeared to be turning slower then usual.
    Tried the deflooding procedure 3 times, didnt do anything.
    Connected a jumpstart, the starter revving at normal speed, still no turnover. Feared to burn the starter (i got no past experience, and the manuel scared me off a bit), i let it rest and tought to call AA in the morning (250$).

    Then i read this article and comments. Will absolutely try this tomorrow, hopefully it will work

  10. Kristof on January 10th, 2016 01:15

    It worked !! Thanks so much !!!

    Connected to car to a friends BMW 3 series (nice battery i’d say)
    It took over an houre cause of mistakes, but we found out how to do this.

    Disconnect the fuel pump and crank the engine for about 20 seconds with the accelerator at 1/3. At some point you’ll hear the engine sputter a bit.
    This isnt enough. Keep retrying untill it actually sounds when its about to start. When this happens, connect the fuel pump AND KEEP CRANKING. Dont make our mistake to stop cranking when you think it fires. Only drop cranking when your engine starts and fires to 4000+ rpm.

    then, release the crank, and keep it above untill your exhausts stop blowing thick white smoke. I did this for about a minute.

    Then slowly bring it back down till it idles. Keep it ideling untill the temperature is perfect, and go for a drive.

    So many thanks to this blog, this saved so much money

  11. Bagheera on January 19th, 2016 11:41

    Brilliant guide!!!

    Spent 3 hours trying to start it using the Mazda method and the fuse method with no luck. 20 minutes using your guide and I’m back up and running.

  12. Murl on February 6th, 2016 21:30

    2005 RX8 My daughters, she let the car sit during the holidays . It would not start.So I just installed a high speed starter, then tried the fuse method no success. I am going to try this method in the morning.

  13. eniola on February 29th, 2016 16:20

    I went on holiday for three weeks and was unable to start my 56 plate rx8 can I use this method as well

  14. spinage on February 29th, 2016 20:09

    Yes I think so. Please let us know how you get on?

  15. Kat on October 9th, 2016 22:29

    Hey Fellow RX8 Owners and Spinage (of course)!
    I was convinced, before even reading the above, that my partners auto electrician and the advice from “Davo” who everyone says knows everything about cars were wrong. So little me read the advice of THE LEGEND SPINAGE very carefully and had given it about 6 or so cranks before my partner left this morning, yelling out his window……it won’t work! There’s no spark! Oh and……DON’T FLATTEN THE BATTERY!
    Where am I, right now whilst writing this?
    Sitting in my Mazda RX8 listening to her motor purrrrrrrrr like a baby!
    Bit pissed that when I called my partner to give him the good news, he “could hardly hear me-bad connection” all of a sudden.
    So Davo and Dino and whomever else was due to come and replace the computer tomorrow, ZOOM BLOODY ZOOM.
    Oh but she’s got no spark……..
    Ha ha ha ha thank you lots for the clear, concise and easy to follow instructions Spinage- I really appreciate it.
    BTW, no it wasn’t me who moved her and then turned her off straight away either. I learnt that from reading the bloody manual when we bought her! xx

  16. spinage on October 11th, 2016 06:32

    That’s excellent news Kat, glad it worked well for you!

  17. Kat on October 14th, 2016 01:27

    Well here in Aust, we like to think we’re a diverse bunch of fun loving yobbos but occasionally can multi task by engaging in intelligent conversation whist throwing the proverbial shrimp on the barbie!!!
    Forums like this, unreflective of yet another opportunity for people just to moan and whinge, can and do actually provide a lot of people (obviously) with a quick and simple resource that provides real, honest AND clearly explained solutions to some very problematic scenarios. Solutions based on personal experience but you’re also humbling in your acknowledgement, should your advice be questioned, that in fact you don’t profess to know everything, are still open to learning new things yourself and respect is reciprocated by all parties! And THAT’S what a forum should be! Very reassuring.
    Honestly, it’s an awesome source of tips and advice for car issues that often prompt professionals to diagnose the worst case scenario because it’s less time consuming with more $$$$ for them to replace rather than restore. My partner had been told by a motor mechanic AND an auto electrician that I’d need a new computer, at the very least, -possibly new coils, sparks etc (which should probably be replaced anyway now I know??). PLUS, by my being more interested in what led to it not starting “suddenly” with her sooooo “out of spark” just made no sense- that’s IF you haven’t mistreated the engine to begin with.
    Anyway, all 3 men have had to withstand a lesson on how a rotary motor works, reasons why it may stall, with simple future precautions to prevent flooding a rotary engine AND the advantages of exhausting all avenues next time. And once they’d finished eating the humble pie I served, they all left with a little less spark themselves, I can assure you.
    And all information gained from LISTENING to others and patiently following the instructions.
    Not to mention how many times I’ve personally used the “no spark” reply to a few selective car conversations!
    Thank you again- you’re doing a remarkable community service.

  18. Chris on October 21st, 2016 15:17

    Hi all ran out of petrol on my 2004 rx8 im brand new to this car and engine and know very little about them . so hope this works as she wont start after running out. Also im only getting 10 miles to the gallon any suggestions on whats wrong would be great .. Thanks so much