Mégane RS4 Trophy - fueling issue?

Mégane RS4 Trophy - fueling issue?

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Champion Hero

Original Poster:

6 posts

58 months

Saturday 30th March
quotequote all
After a bit of advice and help of my 2019 Mégane RS4 Trophy.
Bit of history: had the car since new and had problems with the DESS Battery like everyone else.

A couple of years ago, pulled out of my driveway, got 100ft up the road and car cut out. Attempted to restart, no joy. After a few attempts battery dead. Got it towed to Renault and was told the fuel control unit had blown. Had the FCU and fuel rail replaced under warranty.

Car had had it's fuel pump replaced under recall.

Fast forward yesterday. Car started fine and drove fine. Also fine the day befire.Driving up the road (about 10-15mins from home), slowed to about 20mph then went to pull away again and nothing. No power at all. Then car completely cut out. It kept trying to restart then Christmas lights. Engine failure, brake failure, steering failure etc. Attempted to restart a few times and nothing.

Symptoms are extremely similar to when the FCU blew last time. Unfortunately it got to a point when the battery was too flat to try anything else (including unlocking the boot which is absolutely ridiculous!!)

Recovery truck put a booster pack on, tried to start and nothing. Engine turns over but nothing happening. He also thinks it sounds like a fueling issue.

Is there anyway to test this? If it's the pump or FCU, where do we get these from and are they the same as a standard MK4 meg?

Car is now back home and on charge as can't even lock the stupid thing.

After a couple hours (just enough to keep the dash going nuts) I tried a restart and same thing. Turns over and just choked. From what I can tell, I can hear the pump priming (at least that's what I believe the humming is).
Is anyone able to help? Is there any fuses I can check or a way to test anything? Does anyone know where the FCU is and if it's the same as a standard Mégane?

Honestly losing patience with the brand. I was hoping that the age old thing of french cars having bad electrics was a thing of the past but can't believe they are still as rife. (Sorry for the rant)

RS_MAN_CHILD

232 posts

270 months

Saturday 30th March
quotequote all
Has your RS ever been tuned?

That seems to cause fuses blowing. Battery issues replace for a non DESS solves that issue. Get the Sport 300 570A OEM battery! Ocon had one in the Trophy R used at Monaco few years back! Spanish RS owners have been using the OEM std battery for years with no issues!

Its probably the fuel pump though. Yep when the battery goes or its disconnected the boot locks until you put a new battery in or its got enough charge again!

Fuel pump issues can be avoided just ensure you brim it fill up after every drive. Mine is almost 50000 miles old never had any issues with it but I always keep the tank topped up never running less than half a tank. Simple physics more volume of fuel less the pump has to work as less distance to pump!

Were you the first owner or did it have previous owners who might have got it chipped? That seems to cause issues with electrics! These cars are designed for a certain amount of power! Be happy with that!

I do not think the MK4 RS is any better or worse than other hot hatchbacks just because it has french electrics!

You can either get it towed to a main dealer with an RS mastertech, or RS independent specialist like Dan Johns @ RSS or Mick Pittman @ Diamond motors. Both will 100% be able to fix this for you & take great care over your RS!

https://www.facebook.com/Renaultsportdan/
https://www.diamondmotors.co.uk/

You can even DIY the fuel pump replacement once you have the part! its not hard to do just tricky as you have to remove the rear seat & be very careful around the fuel! This japanese RS mechanic posted a nice YT video of him doing one! https://www.youtube.com/watch?v=GspfYvgYGFg

Good luck anyway. As long as you brim the tank this issue should not happen just avoid running it to low on fuel it will last forever (it overheats when not enough fuel in the tank to cool it down apparently!).Even new Alpine have the same issue for over 2 years now!

Zarco

17,887 posts

210 months

Saturday 30th March
quotequote all
Having to keep the tank half full is ridiculous. That can't be right.


RS_MAN_CHILD

232 posts

270 months

Saturday 30th March
quotequote all
Zarco said:
Having to keep the tank half full is ridiculous. That can't be right.
You don't have to but they seem to fail when run empty! less hassle to keep it topped up LOL you only have to do it once its not like your in an F1 race is it where you have to run on low tanks!

Zarco

17,887 posts

210 months

Saturday 30th March
quotequote all
RS_MAN_CHILD said:
Zarco said:
Having to keep the tank half full is ridiculous. That can't be right.
You don't have to but they seem to fail when run empty! less hassle to keep it topped up LOL you only have to do it once its not like your in an F1 race is it where you have to run on low tanks!
Sorry, but that is complete nonsense on a road car. What about if I want to do a lengthy commute and not fill up every other day?

My mk3 RS Megane has no such issues. I've even run it completely dry once when I tried to get one more run back from work out of it.

RS_MAN_CHILD

232 posts

270 months

Saturday 30th March
quotequote all
Zarco said:
Sorry, but that is complete nonsense on a road car. What about if I want to do a lengthy commute and not fill up every other day?

My mk3 RS Megane has no such issues. I've even run it completely dry once when I tried to get one more run back from work out of it.
Yep I fully agree mate tell Renaultsport if you can find anyone to listen ..... they did not even bother recalling the fuel pump just for some not others when it clearly affects most MK4 RS even 2021 models & new Alpines as well apparently!

Champion Hero

Original Poster:

6 posts

58 months

Sunday 31st March
quotequote all
Cheers guys.
to answer the others who may have missed it in my first post;
Fuel pump already replaced under recall and battery not deemed at fault but did have firmware. I'm the only owner and no it's not chipped.

Some other users in the Renault sport forum are also experiencing additional failures of the fuel pump even after replacement, and Alpine have actually acknowledged this for their A110 owners worr9ngly. Some suggested giving the tank a whack helps. So I've just been out and given the tank a whack. I can only describe what I can hear as some marbles rolling after each whack. 
I checked fuses yesterday and confirmed ok. Also removed the fuse for the ECM as the fault logs where showing cam position sensor failures and the car is throwing anti pollution failure (I think these are red herrings).

Anyway, tried to start the car and on the 2nd attempt car coughed into life for about 5 seconds then died again. Tried again and of course by this time the battery gave up again and threw hundreds of warnings etc

Just watched that video someone posted and it doesn't look difficult to get to the pump, but mostly tricky. My biggest prob is I'm just under full and my drive is on a slight slope so I'm guessing I couldn't do the job as it's not flat?

​​​​​​​Oh I also took the fuel line off after and there was a dribble of fuel, but not much. Once the battery has enough juice in it I'll take that line off again and try and start it to see what sort of flow comes through... Should it be a flow or just a squirt?

And ftr, I always fill up when the light comes on or just before. It's never run dry

Champion Hero

Original Poster:

6 posts

58 months

Sunday 31st March
quotequote all
Just an update, it does look like it's the pump. Got the Mrs to turn the car over whilst I unplugged the fuel line and nothing came out. So this will mean that technically, I'll be on my 3rd pump in 4 years. That really can't be right

RS_MAN_CHILD

232 posts

270 months

Monday 1st April
quotequote all
Champion Hero said:
Just an update, it does look like it's the pump. Got the Mrs to turn the car over whilst I unplugged the fuel line and nothing came out. So this will mean that technically, I'll be on my 3rd pump in 4 years. That really can't be right
Some people have gone through the same amount...even new Alpines have fuel pump failures (same engine as the RS Mk4). In future after getting it replaced try filling it up to the the top then regular top ups so never less than half a tank! This is what I did since owning my RS from new....over 50K miles later never once had an issue with the fuel pump or ever being stranded at all. Mine has started first time every time. Only issues for me are tyres & brakes wear & tear items due to high miles.

Champion Hero

Original Poster:

6 posts

58 months

Tuesday 2nd April
quotequote all
My tank was just 1 bar under full when it failed.
The keeping it 1/2 full is crazy though - you're effectively running the car with a 25ltr tank. it's a workaround sure, but not a long term solution.

RS_MAN_CHILD

232 posts

270 months

Tuesday 2nd April
quotequote all
Champion Hero said:
My tank was just 1 bar under full when it failed.
The keeping it 1/2 full is crazy though - you're effectively running the car with a 25ltr tank. it's a workaround sure, but not a long term solution.
Did you always run it with plenty of fuel in though? That's the issue I think. I bought my brand new straight away it was drinking way more fuel than my MK3 Megane which had a 60L tank & less power.

So I just started to brim it whenever possible...over 50K miles later mine is still going strong no issues at all. Its not ideal but a 50L tank means one decent run for me consumes 25L sometimes as much as 30L over 150 miles of intense driving in Race mode so for me it makes a lot of sense to keep mine brimmed!

I look at it this way less hassle to brim it than have it fail as even new Alpine have fuel pump failures so its not like Renault even know the solution do they if the uprated pump also fails for some!