Just some fuel pump advise (Phase 2 MK2

Hey everyone,

Car in question:
2006 Megane F1 (Fernando Alonso F1 champs 2005 edition plaque #1100)

I have been fuel pump crazy this week. Reading all the threads, adding my 2 cents etc. but thought I'd post a thread on my findings.

Use it, don't use it but it might just help someone out.

My story starts waaaay back after I bought the car(April 2014). Was perfect, well I though so being used to Golf Mk1 rabbits etc. Did a 700km trip to my folks in the Eastern Cape here in South Africa and car was on point.

Shortly afterwards(mid 2015) I wanted a bit more so booked it in at RSTuningSA (Our SA guys names is also Paul, go figure haha). On my way there (which is a 450km trip) adn with around 100km to go I started getting stutters from the engine. I'd plant the throttle and then the car would either cut out or misfire. No biggy I was on my way to the right place.

Take note that the fuel cutting and misfire only occurred after a long drive and whilst zipping around town it did not occur.

So RSTuning mapped the car to the 76mm straight pipe after doing a de-cat. Paul suggested I replace the fuel injectors since that see to be the problem with the misfire. Great, he had some working 2nd hand ones off a 225 for half price. He installed them and after a few days I collected the car and drove back to my city. Just over halfway the misfire and starvation issue occured again. Okay I forgot one thing, Paul suggested I change the fuel pump as well, whole sender unit (these are expensive at Renault) and not to install another pump in the sender unit. Apparently the wrong pump can cause the fuse box under the bonnet to burn out or something (read this here on RS Megane as well if you install a too ampy pump on the stock loom so I suspect he meant that).

Anyway, I'm a DIY'er and a cheapskate so I phoned around town to get a new pump. Dealers wanted just below 4000ZAR and Bosch dealer wanted 2500ZAR for the whole unit. That is a lot of moneys for me, well it was even more for me in 2014 due to different pay at work etc.

The Bosch guy said he sells the pump only for R500 which I then just have to install in the sender unit. Of course I opted for this. Next step: Remove the sender unit.

My fellow Megane people, removing the locking ring on the tank for the first time in over 10 years is a nightmare. I obviously did not have the $ for the correct tool and the correct tool is not available regularly in SA, so would have to ship it in at much cost. Went to a friends workshop (after miserably failing to undo it by hand) and asked him for a tool, we tried his tool (the 2 prong U shaped one) but this did not work. Finally we used two big ass screwdrivers, using one as a horizontal flat bar and the other as a leverage tool to undo the ring. Okay locker ring removed.

Removed the sender unit and started looking at it as though it's a piece that went together automagically.

Finally saw that the bottom part must be removed which again enables you to remove the pump unit itself.

We did not know how to remove it so we twisted and turned. Even snapped one of the tabs off which looked like a starting point. Finally i held the bottom and my friend the top and we twisted and pulled and turned and it snapped off, me landing on my arse and he almost tripping over another car behind him. Great, we had it apart.

On inspection we noticed it was not a twisting unit but rather just clipped together. Remove the stock pump and installed the new Bosch pump. The stock and aftermarket pumps are exactly the same except for the feeder nozzles. The stock one has ribs and the aftermarket is smooth. See pics.

Fitted the new pump and compressed air cleaned the stock strainer filter. Refitted everything and installed a new fuel filter. The 2006 F1 has an in line fuel filter.

Although I did all this I was unsure if the problem is solved since it only occurred on trips longer than say 300km and I don't travel far that often. So I just hoped for the best.

Last year December we went to get my girlfriends mom for Christmas and its a 450km trip. On our way there we suffered some issues again, on overtakes especially I could not plant the throttle since it would cut out and go, cut out and go ......

It was also linked to ambient temperature since when we returned it happened again but only until sunset when the temps started dropping and it also rained a bit. Then the car was again fine. Very strange symptoms indeed but at this point it was lingering for most part of 3 years.

So in 2018 I spend my bonus on more Megane parts. suspension parts this time, imported from the UK. Powerflex bushes and then locally got the tie rods plus ends, rack end and ball joints. also ordered the TFD rack bush but unfortunately that seems to have been lost my either the Royal Mail or South African Post Office. I never got it.

So no $ spend on fuel issue lingering in my subconscious.

Met a few lads here in town who tagged my car with a business card asking me to join their group since they all have Megane Sports.

Went on a run on 3 November and the car was good although it still would only sustain .6 bar of boost after hitting 1 bar and falling. Sometimes it would hit 1 bar + and hold it but that was rare.

Then Wednesday afternoon after work I poppe din at the local grocer to get some buns for hot dogs and on my way home from there ( a 4km commute) the car started behaving real bad. Starting from the traffic light it would completely loose all power and basically shut down with my foot still down on the throttle, then suddenly jerk forwards and then either repeat or I'd ease off the throttle and just sustain drive with minimal input.

Come Thursday I jump on every forum and resource I can find, some suggest brake pedal switch, others battery issues but some also fuel system including fuel pump.

Since my car has the fuel filter I decided to first replace that and see what happens. Its a 100ZAR part which is cheap enough. At lunchtime I set off to the auto store (Midas) to only barely make it there. The fuel starvation issue has escalated into a nearly undriveable car. Got the fuel filter and new oil filter since my service is also due and had about 15km to go to get back to work or go home.

Decided to go home since it's highway, less stop and go's since car doesn't want to GO anymore. Got to the off ramp of the highway and the car just refused to accelerate any more. I was stuck doing 20km/h on the highway.

Got to a slight incline and there the car just stopped. You know that sound cars make in the movies when the oke is driving across the country to get to the love of his life and the car breaks down, that clak_kla_klak sound haha? Well mine mad ethat sound and there I was, stuck alongside the road, luckily we have some shoulders on the highway but the trucks still squeeze by and whole car jerks when they pass.

Primed the pump by holding ignition in for 10 seconds, switch off, repeat and repeat. Started again and up the hill we went although back to 20km/h

Went another 1km before it died again. Stopped again, repeat procedure and finally got home.

Firstly swapped the fuel filter. New filter I could blow through without any strain. The old one, after removing all fuel from it, I had to blow real hard to get air through. So my thoughts were, "this must be it"!

Replaced and started car... Seemed fine so dressed again while car idles into work clothes and when I got to the car I heard it struggling to stay alive. Put foot on the throttle and pressed but all it did was die.

So next is the fuel pump. Had a new pump laying in the garage for 2 years, originally bought it to help my brother with his Chevy Spark 800cc but that turned out to be the distributor so I kept the pump. Cheap Autozone pump 3.8bar but specs say its good for a Nissan 200sx (same kinda flows as a Megane RS).

 

Did the following (posted in another thread):

0. Take photos of the whole process. Will help with wires etc when re-assembling.
1. Remove rear seats (horizontal and vertical ones, horizontals just clip out)
2. Remove two torx screws holding the plate in place over the pump.
3. Remove the plastic plug which holds the carpet down.
4. Carefully remove the rubber/plastic cover which sits above the pump. It breaks real easy.
5. Get a vacuum and compressed air, keep running vac while blowing compressed air over the pump top. It gets real dusty in there.
6. Unclip the two fuel lines. Or 1 if your pump is different. Mine has two but also an in line fuel filter under the left wheel area. You might want to release the pressure in the lines first, I remove my fuel filter line but since you dont have one maybe remove line from the fuel rail to release pressure? Maybe someone else has an idea here.
7. I strongly suggest you get a very specific ring lock removal tool that works on the megane. I did not have one so used two big ass flat screwdrivers and a size 20 spanners open end to hook the little extrusions on the ring. I also bend some of the metal on the pump hole surround so again strongly suggest you get the right tool.
8. Once ring is loose, pull the pump out and at some point turn is like 45 degrees to get the float level out, watch out for spillage, surround the tank hole with some towels. (put a plastic bag over the open tank hole)
8.1 Remove the big O-ring which seals the unit and tank. Keep it, you can reuse it.
9. Empty the sender unit from all petrol
10. Remove the float level reader by unclipping its two wires from the inner top. Then slide the reader unit downwards to get it disconnected from the rest of the pump unit. You want it out of the way to not get damaged.
11. Unclip the other two wires, blue and black, one is fatter than the other.
12. Pull the top of the unit upwards so that the two guide pins are out of their guide holes, remove the center spring.
13. Now another tricky part, take something very thin (I used 8x8 RC airplane propeller) and insert it in the notches at the bottom of the unit. The part which has all the lines at the bottom must be removed by unclipping but its a PITA, so take the thin thingy and push it in the side and then pull it around like opening a can. Do on both side and eventually you will see it starts popping open. Then just pull it apart with a bit of muscle.
14. Now you have two pieces, the sender unit top and bottom. The bottom part has another part inserted into it which contains the strainer filter thingy.
15. Remove the pump by just pulling it down, watch out for the o-ring and plastic thingy which looks a bit like a castle.
16. Remove the strainer by pulling upwards. This is in the bottom part we removed earlier.
17. The strainer might be really filthy, Mine was so bad and I could not clean it so I cut it off from the rest of the unit and used a round strainer which came with my new Bosch pump. Modified it a bit buy cutting it down (the connector to the pump) so that when combining the top and bottom parts again it just doesn't press against the pump units bottom.
18. Install the new pump by simply adding the plastic castle looking thingy and then the o-ring. Press into the housing.
19. Insert the strainer part back in the bottom unit if re-using, or like mine the half part since I cut the original part away.
20. Click the bottom and top back onto each other.
21. Insert the units top parts guide pins and spring back in place. Connect the fuel pump wires.
22. Slide the float unit back on its place. Its correct position is 90 degrees with the fpr. Refer to photos taken.
23. Connect the float wires.
24. Connect the sender unit to the wiring loom, insert key in car then press and hold the start button until the ignition turns on, you will hear the pump whirr for a few seconds and stop. This is correct. Chekc that the fuel gauge reads the position of the float level. I switched off the car a few times, changing the position of the float to ensure it works correctly.
25. Turn car off and then insert the sender unit back in its place. There is a single guide key on the unit and you will see it matches a slit in the tanks hole.
26. Only once the sender unit is in but you are not pressing it down, insert the big O-ring. Way easier doing it this way around than before installing the unit.
27. Now press down on the unit aligning the key so its in the correct position.
28. Start swearing again whilst trying to screw the lock ring on without it going skew, The lock ring has a arrow marking on it which points to the starting point of the thread. The starting thread on the tank faces to the rear of the car exactly. You might feel it goes skew a bit when just starting, you can press down on the highest point and it might just click down and then you can continue screwing it down. Keep feeling around the sides of the ring for the remaining threads on the tank. It will give you an idea if it is still skew. All this time you must keep pressing down on the unit to keep it in place until you are sure the threads are straight and your down at least one full turn.
29. Once hand tight, use the tool and tighten it so the arrow points towards the front passenger seat.
30. Connect the harness plug, the repeat the process to turn ignition on/off for about 4 cycles. This will prime the system up to the rail. Start the car, it might take a few swing if its not fully primed yet.
31. Check for any leaks especially when filling up the next time. If the lock ring was not screwed on straight it WILL leak.

The biggest concern i found is the stock strainer which get clogged with dirt and grime. I could barely blow through it whilst the new Bosch strainer was breathable. This will result in the pump sucking in fuel but the fuel struggles to get into the little compartment which the pump feeds off directly. The fuel demand might be higher than the amount available or the pump might suck air or even create a vacuum with limited fuel supplied to it. Take this example, just the pump motor connected to 12V source, submerge in water and put your finger over the inlet, the pump immediately sucks your finger onto the inlet. It has a lot of suction. If the strainer is so clogged that it struggles to get fuel through, you will not have ample fuel flow to the injectors and thus fuel starvation.

After this the car holds boost at 1.1 bar through the gears, throttle is responsive and consumption on the onboard computer is definitely better. Still have to measure this on a long distance trip but we'll see.

Apparently the R26 only has the in tank strainer filter? If you ever start having any of the symptoms I listed in this post, you might want to start checking the sender units strainer filter. Hopefully the fuel is cleaner in the UK and Europe than here in South Africa.

Guys, hope you have enjoyed my write up. It is by no means a sure thing that it's your issue with similar symptoms but I hope this might help someone somewhere who wants to save a few bucks. This is personal experience from owning this car for almost 5 years now.

Feel free to comment and voice your opinion or experience in this matter. If I ever take the sender unit apart again I will take pictures of exactly how to do it without damaging the unit, especially the bottom part.

 

Forgot the ribbed and rib less difference between the two pumps picture.