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760 hpfp diy

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diy hpfp
106K views 218 replies 60 participants last post by  Big N Fast 
#1 · (Edited)
original post with a lot more info(if your in to that kind of thing :) ): http://www.bimmerfest.com/forums/showthread.php?t=681883

Do not respond if someone says they can rebuild your pump for 800$ 1200$ or 1600$ all there doing is whats listed in this guide. noone has any proof that they can obtain anything othere than a non-factory diaphram

This guide will show you how to replace the high pressure fuel pump diaphragm

Before you begin I would recommend that you visit MWS's youtube page and look thru the videos about the HPFP
it contains valuable info on how the top part of the pump comes apart and if you have any issues afterwards

(like not removing the pump before opening it up !).

https://www.youtube.com/user/slkttop/videos <<< MWS on youtube
http://s288.photobucket.com/user/usdrake1fallen/story << my Photo bucket

Before attempting this procedure you need to be sure that your hpfp is the culprit and that you don't have any other parts in your fuel system that could be causing similar problems.

This should take no more than 30-45 minutes per side. Drivers side is the hardest becase of all the tubes/wires/tanks/engine stuff

Parts / tools:

2 Magna fuel diaphram's part# MP-9400-03 one for each side. 16.97 each + shipping from Summit racing http://www.summitracing.com/parts/mrf-mp-9400-03

Needle nose vic-grips

Sharp razor.

Paper towels to soak up fuel.

flathead screwdriver.

Now on to the actual repair:
1. Remove black vent hose by pushing in on the black piece circled in the photo.
2. Put some towels down under the pump to collect any fuel that might drip out of the vent lines !
3. Loosen screw connecting the vent pipe on the top of HPFP or remove it from the pump. It might be on there really good so make sure the
clamp is loose enough for it to freely more around the tube then give it a good pull it should come off without too much effort.



4. Remove all four screws on the outside of the pump with your vic-grips and make sure you can move it around and that is loose from the engine
THIS IS A MUST DO NOT SKIP THIS !!!



5. Now it is time to remove the cap on our HPFP. Loosen each bolt just a little bit each pass until they are all out. Be Careful once all the screws
are out under the cap there are a SPRING, METAL RING, BLUE O-RING AND A CIRCULAR BLACK CAP to remove.



parts removed



6. Now that those item's are out of the way we need to remove the ring that holds the diaphragm in place. Use your fingers in the center of the ring
to pull it out of the pump. USE LIGHT PRESSURE UPWARDS ON THE PUMP MAKING SURE IT DOESN'T GET COCKED INSIDE OF THE PUMP AND GET STUCK ! You can also use a socket that fits snug inside the hole and pull it out with light pressure



7. Now it's time for the tricky part removing the diaphragm. Yours might be stuck to the metal ring we just took out. It might be stuck inside the pump or it might be loose inside the pump. If it is loose inside the pump just use your nails to get the edge up and pull it out. If it is stuck inside the pump you can poke a hole in the middle of it and use something like a small electronics screwdriver to get it out. What even you do do not scratch the inner surfaces of the pump !

8. Now its time to cut our new diaphram. place the larger thicker metal ring inside the magnafuel diaphram and then very carfully go around and trim the excess material off on the outside.







9. Compare it to the old diaphram and make sure it is the same size.



10. Place the new diaphram inside the pump and make sure it fits nice and there isnt any gap that could let fuel get by.



11. Place the metal ring back inside the pump nice and evenly making sure not to angle it so it doesn't get stuck



12. Replace black circular plastic piece and the blue oring. The oring is kinda tricky but it has a groove that it goes in and once you get it back in
it will stay there for the rest of the assembly.

13. Now replace the thinner metal circle with the high part facing up and the spring back on the pump with the top cap. You will need to compress the top cap and hand tighten the screws. If you have a inch pund torque wrench tighten the bolts to 69 INCH-POUNDS.

14. now insert the four long bolts that secure the pump to the engine. You might need to push the pump down to get the bolts started. Make them snug Then
tighten them a little more than that.

15. Reattach vent hose to the nipple on the top of the pump.

16. attach the 2nd vent line by pushing the two line's together till you hear or feel it click together Then give it a little tug to make sure its
together

17. Now we need to get fuel back into the fuel lines and pum. Turn the ignition on to position 2. Foot off the brake and push the start button.
Repeat this about 5 times then start the car and let it run. because the fuel system was open the engine may not start immediately there may be a
2-3 second delay.

17. YOUR DONE !!! GO GET YOUR SELF A BEER !
 
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11
#5 ·
Thank you for your valuable post usdrake1fallen.
I really want to follow and work on my own car. It has been rough idling for a couple of years and recently started long cranking before starts.
By the way, why you need to loose the pump from the engine first? Does it make it even harder to work on the pump when it is loose?
You emphasis not to skip this part. I want to make sure I understand the reason behind this.

Thanks
 
#6 ·
If you don't loosen the pump from the engine the pumping mechanism inside can pop up and cause a malfunctioning pump witch can limit your revs to 4500 rpm engine stumbling and the same problems you would have if you have a bad diaphragm. the piece inside is a pressure fit. so if you dont loosen it the pressure of the cam will cause it to pop up and lead you to remove the pump from the car putting it on a bench and hammer all the parts back together. it is not visible to the naked eye if the rod pops out. i attached a picture with the pump internals laid out. the big shaft in the picture is what pops up if you don't loosen your pump.

here is a link to the 30 page thread with tons of pictures and more information:
http://www.bimmerfest.com/forums/showthread.php?t=681883&page=17
 

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#7 ·
So loosen the pump is to release the spring pressure under the dump? Is there going to be a lot of fuel coming out from the bottom of the pump? There is an o-ring under there as well, how possible the 0-ring need to be replaced?
It looks a pretty strong spring, is human hand strong enough to push it down a fit it back in? Does it help if I only remove 3 of the 4 long screws and leave the last one lossen but attached? By the way, do you have size / model of the blue o-ring may be I have new ones prepared first?

Sorry for many question. I am not a professional mechanic, as not mechanics in Hong Kong is willing to do this for me. So I decided to give it a try myself.
 
#8 ·
The only place fuel will come out of is the top of the pump. no one has had a problem with the o-ring. I am not sure of the size. When you unscrew the 4 long bolts just make sure you can slide the pump up and down making sure it is free from pressure. When you put it back on it will be pulled down by the screws no force is needed to reset the pump. mws has a video of him removing the pump. the link for the videos is at the very top of the first post. If you do replace the o-ring make sure it is suitable for use in fuel and oil.
 
#9 ·
Thanks again. Couple of more questions: once the 4 long screws are removed, does it allow the pump to move ouy freely with the 3 fuel lines still attached? The video shows the each pump has 2 green diaphragm, is one diaphragm good enough? How thick is the MP-9600-03 diaphragm? The Magnafuel seller in ebay does not ship it to Hong Kong for some reason. Is there other material can be used? such as Gesket sheet?

Thanks
 
#10 ·
you just need 1 magna fuel diaphram per side. im not sure of the thickness but mine have been working for 20000 miles.
 
#11 ·
I finally got the Magnafuel diaphragm ordered and the tool ready. Waiting for delivery.
Just a little anxious before doing this. Couple more questions hope you can help:
1. What could have happened if the car does not start after this rebuild? I will rebuild one by one, does it matters which one goes first?
2. Does engine old coming out when the pump is released from the engine?
3. Is there anything else I need to paticularly pay attention to?

I will do this rebuild next week.
 
#12 · (Edited)
1. It does not matter which one you rebuild first. You may not have to rebuild both if you do not have fuel coming out of the caps on both pumps. If both are bad. Do passenger side first. It's the easiest one to get to. Make sure you have all the fuel out of the recovery lines before you start the car.
2. The oil in the engine does not go up far enough to the pump. You may have a couple of drips. But nothing you need to worry about. Again do not remove the whole pump from the car just loosen it enough so there is no pressure, on the spring inside the pump.
3. Make sure you block off areas around the engine with towels or rags. Because if you drop any part out of the pump and lose it they are not available. Be extra careful when removing and replacing the cap. That's when parts fall underneath the car. Make sure you torque the cap down to the inch pounds specified in the instructions. One thing you need to check before doing the job. Is to make sure the problem is not the fuel pipe valve on the firewall. Check the fuel vent side of the valve. Remove the hose and start the car. It should only shoot a few drops of fuel out. It should not be continuous. Four of us on the site and have repaired pumps only to find that that valve was defective. One other part that needs to be replaced regardless is the fuel return filter located next to the fuel filter. BMW shows no service necessary on this filter. However several of us have found them to be plugged. Thus not allowing fuel to return to the tank. Feel free to PM me. If you'd like to discuss this over the phone.
 
#13 ·
+1

1. I do recommend removing all four bolts completely from the engine just for extra security.
(it doesnt take much pressure to dislodge the center of the pump)

2. you may get two or three drops of oil but most likely nothing.

3. like stated you should replace your fuel filter and return fuel filter.

4. on the drivers side the oil tube will make it a little difficult so start with passenger side first
 
#15 ·
The only time you need to replace the diaphragm is if you have fuel coming out of the vent pipe. On the top of the pump. But make sure the fuel is coming out of the pump and not traveling to the top of the pump from the vent lines.Several items can fail in the system that will cause fuel to enter evaporative fuel vent system. Pull the vent lines off the top of the high-pressure fuel pump's. Start the car, if you have leakage from another area, you will have a small amount of fuel come out. The fuel that settled on top of the diaphragm. However if it stops then you have fuel leaking from somewhere else getting to the top of the diaphragm not coming from under the diaphragm. (On the pump side of the unit) If you have fuel coming out continuously then the diaphragm is bad.
 
#16 ·
Well I pulled the vent hose I suppose u circled it as number 2 above and (engine off)it was continuously fuel coming out of the pumps nipple and I had to put the hose back cause engine was hot .but when I pulled the other vent hose on the passenger side there was no leak .so u do think that would be a great chance to repair the diaphram :)?
 
#18 ·
Yup. Follow the diy !
 
#20 ·
Hi Folks,

Firstly many thanks for this thread, Godsend when BMW told me the cost of essentially repairing a rubber diaphram pump!

So I have followed the procedure to repair the diaphrams. BMW dealer was correct there was an internal leak on one bank only, (obvious holes in both diaphrams on that side). Replace both sides anyway so they are the same.

However I havent spent any material time trying to get the fuel out of the vent pipes and I havent yet replaced the fuel filter or the tank reciculation (carbon canister) filter. I didnt think that this would be required at this stage. I was going to do this later.

So the long crank and the random car stalling have NOT gone. If anything the crank is longer now than before. However the car seems to run better now and smoother than before.

Any ideas what I should check? The pressure in the system is lost quite quickly. Only a minute after turn off it takes about 1 sec to start. If you leave it 5 mins it takes 2 seconds of cranking to start.

How could I check tank valves? Could they be the reason for the loss of pressure? I dont think so.

Any help appreciated.
 
#21 ·
Check the fuel pipe valve on the fire wall, three fuel lines run to it. The one closest to the outside of car, is leak line. The other two are close to each other on the same side of the valve. Pull the leak side to see how much fuel is coming out when car is running. It should be little or none. The valve could be leaking and filling the vent lines back up with fuel..
 
#22 ·
Thanks for your quick reply.

I will check this over the weekend and let you know. To make sure that Im checking the right thing, do you have a picture or a part number for the valve? Obviously I want to be sure I will leave only the leak tube disconnected otherwise i guess fuel will go everywhere!!!

One intresting thing is I plugged in the car today to figure out what the amber check engine light was that came up when i first restarted after the fix and it comes up as a fuel pressure too high error. What could this be point to. Could it actually be some other component (example the regulator) that has failed and the high pressure actualy caused the rupture of the diaphram in the pump to relieve the pressure? Thoughts?
 
#25 · (Edited)
Thanks for your quick reply.

One intresting thing is I plugged in the car today to figure out what the amber check engine light was that came up when i first restarted after the fix and it comes up as a fuel pressure too high error. What could this be point to. Could it actually be some other component (example the regulator) that has failed and the high pressure actualy caused the rupture of the diaphram in the pump to relieve the pressure? Thoughts?
Don't worry about the codes till you get fuel pressure is regulated in the vapor recovery system. The car will throw codes till the system is clear of fuel. Mine did. Clear after repair and see if they come back. The sensors are hard to get to. Intake manifold has to come off.
 
#24 · (Edited)
If you're not getting fuel out of the top of the diaphragm leak line. Then pumps are ok. High-pressure codes could be thrown after system filled with fuel. This was my experience. Also the main fuel filter has check valve built into it. Also had trouble with it. Replaced both filters no problem afterwards. Here's a picture of the fuel valve on talking about. Notice the three hose clamps. The hose clamp on the right side of the photo is the leak side. little or no fuel should come out of that side of the valve.. Just a few drops/dribble is all as it balances out the fuel pressure. Once balanced, valve should seal tight.
 

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#26 ·
Unfortunately I broke down last night while on the motor way I started to loose power as if I was running out of fuel. The engine would turn over but not start now. So I clearly have bigger issues now that I need to investigate. Oddly I had just done two journeys before that of about 60-miles before hand and the car seemed ok while driving. Now really not sure what to check.
 
#27 ·
It is very possible that the car shut itself down because of multiple codes. However the fuel pump in the fuel tank may have failed also. To check that see if the fuel pump is running when the ignition is on without pressing the brake pedal. Another words Insert key in slot. Press start button but don't put your foot on the pedal and see if your getting fuel to the engine. If you're not then the pump is not working in the fuel tank. When was the last time the main fuel filter was changed? I doubt it's blocked if it was running ok before that.
 
#28 ·
The car turns over ok and sorts of splutters but never starts. There is no limp mode warning which it has done on start a couple years ago when things were not good when starting. Basically it tries to start. Which is pipe from the tank? It is possible that the tank pump failed.

I think the fuel filter would have been changed at its 100000 service. But it felt fine before at load and high revs when high fuel flow was needed so I don't suspect the filter.

Do the tanks vent to the air? Or is it controlled only by the tank vent valve? Maybe a vacuum build up might have starved it of fuel?
 
#29 · (Edited)
Not sure about the vacuum issue. However I doubt it. The system is sealed so vapor does not escape into the air. It goes through the charcoal canister. Pull the line off the front of the fuel filter. Do the start test with someone helping you,so fuel doesn't go all over the ground. Not sure where fuel line enters into the engine compartment.
The fuel rail system is extremely complicated. Check www.realOEM.com to see the assembly. You will understand what I'm talking about. There's 100 page PDF file on the N73 engine. I'll see if I can find the link and post it later. This may help you also. Good luck.

Here's the link to the service bulletin I mentioned above.

http://www.bimmerfest.com/forums/attachment.php?attachmentid=331538&d=1341385350
 
#30 ·
Many thanks for the document very helpful.
just a quick reply to let you know what I found.

I removed the leakage pipes from the pumps and found fuel so suspected a leak. I opened one pump and found that the diaphragm had delaminated. (I will attach a picture later). Essentially what I could see was that the diaphragm was sealed against the pump housing ok since the ridges on the ting were embossed on the rubber. The diaphragm has slightly stuck to the pump body. However the piece of the diaphragm rubber coating that was exposed to the middle of the ring had separated from the canvas core of the diaphragm. The only thing holding that rubber in place was the little embosed circle in the middle of the diaphragm that was clearly part of the magnafuel manufacturing process.

So now I'm asking, what I did wrong and if this diaphragm is strong enough and how other have made the fix successfully.

I have 2 spare parts that I can use but I need to now figure out why this happened, since if I do the same again it will de laminate again.

Thoughts?
 
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