This weeks blog post is a little lack luster, just due to so many other big things happening right now. Track prepping for Saturdays event, Finishing up Pats K swap, completing Ever’s NSX top end gasket overhaul (before the track event on Saturday), working 40 hours a week, and trying to sleep somewhere in between.
The last track day I did in my K20 EG, my Walbro fuel pump died. After more than 10 years of amazing service it finally went kaput, dying halfway through the event. Luckily Patrick had an extra OEM GSR pump that I threw in just so I was able to enjoy the latter half of the event, and actually go on to PB. Of course an OEM GSR fuel pump isn’t the most ideal pump for a tuned K20 with 250 hp. I just didn’t want that dead pump to put an end to my day. After that event, I drove my car home and parked it away in the garage, never touching it for a few months while focusing my attention on tracking my 4 door. As I ordered more and more parts for my 4 door, in the back of my mind I knew that I really needed to get a new Walbro fuel pump for my EG. An OEM GSR pump is anywhere from 80 LPH-131 LPH (liters per hour) depending on what year GSR. This was definitely not going to provide adequate fuel for my thirsty K20. An OEM B series injector size is 240cc, while the OEM K20 is 310cc. The Walbro pump I was previously running was the 255 LPH one which is 2-3 times more LPH compared to the OEM GSR pump I was running. The Walbro pump was definitely more suited for the larger injector on the K20 and the more demanding tune it has on it. Finally one day I decided to pull the trigger and order a replacement pump. As you can see from the facts, there was defiantly a risk of leaning out my engine, and possibly doing damage, so I really needed to get a replacement in before I drove the car anymore.
See even though this post seems a bit remedial, there are some good educational facts that I bet you didn’t know before.
This should be a no brainer, but I wanted to mention it anyway. ANYTIME you are swapping ANY motor in your car… Honda, Nissan, Toyota, etc… you should ALWAYS put an after market higher LPH fuel pump in to help ensure proper fueling. Yes most people will get a FPR (fuel pressure regulator) and gauge to complete the upgrade, but at the VERY least get your self a new higher flowing pump. A higher flowing pump will help keep the fuel flow consistent.
On to installing the new pump in my car, which was just another Walbro 255 lph pump… Since my Eg is all stripped its very easy to access the fuel pump, BUT if you have full interior don’t worry ill try to guide you through the process of getting to it. All you really need to do is just remove the “bench” part of the rear seats. This is done by removing the (1) singular bolt that holds it in place, and it can be found by squeezing a socket in-between the back of the rear seat and the bench part in the middle by where the seat belts come thru. Once the (1) bolt is removed you can lift the “bench” part up, making it somewhat vertical then you will be able to slide out the metal tabs that “lock” the front part of the “bench” to the chassis. I make it sound more complicated than it is, but trust me its very easy. What you will now see is pictured below. The silver cover is the access panel to the fuel pump. The cover is slightly different between chassis but its all the same method. Before you do ANY of this, please disconnect the battery and its probably best if you don’t have a topped off tank. Remember that you are dealing with highly flammable stuff here.
Remove the X4 Phillips screws that hold the cover on.
There should be enough slack in the wires so that you can just slide the cover out of the way as seen below.
There is a clamp on the return line. this is easiest removed with a 45* or 90* needle nose plier.
If the line is reluctant to come off, try pushing it on more. This will sometimes help break the seal and allow the line to come off easier. DO NOT go crazy with pliers and mess up the line, this can cause leaks and be a real headache.
This is the fuel pump power. just simply unclip and move out of the way.
Lastly the 17mm banjo bolt that is the fuel pump outlet (supply line)
Make sure when removing the banjo bolt that you pay attention the X2 crush washers and don’t lose them. You can reuse them, I’m sure people say this is a bad idea but I have done it multiple times in my life and have had no issue. If this makes you feel uneasy, you can always just throw X2 new ones on to be safe.
Now remove the X6 10mm nuts that hold the fuel pump assembly to the fuel tank.
Once they are are removed the whole assembly will easily slide out of the tank. Be gentle when you take it out as it might take some contorting to get it all out. Don’t just force it out, it may take some time but it will come out.
This is what the whole “unit” will look like once removed. (again different chassis may vary slightly but it will all be done the same way.
To remove the fuel pump, begin by unscrewing the Phillips screw that has the ground attached to it. This screw is a one time use locking thread screw, I usually am able to reuse it though. If when you go to tighten it back down and it doesn’t get tight you will need to use a new or different screw.
Once the ground is removed you can now pull the pump from the bottom of the hanger assembly. There is a rubber grommet that holds it tightly in place, just use some force to free it. (you’ll see what I mean when you get to this step.)
To free the pump filter there is small circular clip that holds it on a plastic tab. It can be challenging to get it off just because the rubber grommet is on the pump and leaves little room to access the clip. I usually use small picks, and don’t really care if I damage the old pump (since I’m replacing it anyways) The new pump should come with a new filter, and clip anyway. The only thing you are concerned about is the rubber grommet because you will be reusing this.
Next loosen the clamp holding the hose to the pump. This can also be a pain to remove, and most fuel pumps should come with a new hose. Usually I just take a razor and slice the hose to easily remove it. (this hose came off easy so I didn’t need to use a razor)
Now there is a “safety” clip that needs to be removed before you are able to actually unclip the fuel pump power wire.
Use a pick, or something with a really small point that can depress each side.
This is what the “safety” clip looks like once removed. Now you are able to use you finger to unclip the power wire from the pump.
This is what it looks like all taken apart.
Here is everything that comes in the new kit.
Old GSR pump on the left and new Walbro pump on the right.
Everything that I will be using from the kit. Notice the new small silver clip that holds the filter on the pump. (its sitting on the filter)
As you can see there is a difference in the actual lengths of the pump. this isn’t a big deal.
Just line up the pump and ensue that the over all length, from the bottom of the pump to the top of the rubber hose is the same length, as seen below. (I made the new hose slightly shorter because the old one was a bad bit too long)
You must put the rubber grommet on before you attach the filter. in the picture below you can sort of see how I have the silver clip on the nipple coming off the pump. You will need to use a pick or small pointed equivalent to press the clip on. (this is sort of challenging and its best to use a second set of hand to help)
It’s important that you have the correct length hose. Too long and you won’t get the pump to go on the hanger. Too short and the pump won’t have enough pressure to secure it to the hanger. You can also finely tune this by adjusting how far the hose goes on the metal tube attached to the hanger assembly.
It’s also important to notice that the grommet only really fits one way. It’s pretty obvious as it fits the contours of the hanger. The filter also only goes on one way and there really isn’t a way to do it backwards.
Now reinstall everything you just removed. Once you have the new hose on and tightened with the pump perfectly wedged in the hanger. You can now reinstall the power wire clip. (make sure you hear it “clip” in.)
Now reinstall the “safety” clip
Re install the ground wire.
And don’t forget the keep the install clean by reattaching the plastic black clip on to the hanger.
With everything all securely reinstalled you are now ready to put the whole assembly back in the tank. Just like when you removed this you will want to be careful and not force it back in. There will be more contorting to reinstall it, you will feel when its actually in properly because it will just sort of fall into place, as if it members how it was before. You can mess up a lot if you get frustrated and just jam it back it, just take your time and ease it in. (lots of twisting, and different angles will help get it back in)
Once its sitting in completely flat on the tank you can reinstall the X6 10mm nuts, and tighten in a star pattern evenly. Be careful to not pinch or damage the gasket because that can lead to leaks in your fuel system.
Notice that it looks like there is a “stuck” on crush washer. Actually though, it’s just a part of the mating area. So DO NOT try to pry it off! (see below)
Now take one crush washer and put it down.
Put the banjo fitting on top of the crush washer and slide the other crush washer on to the banjo bolt like below. Now you can thread the bolt in and tighten (you don’t want it to leak, BUT don’t go crazy)
Reinstall the return line.
Reconnect the power wire.
place the rubber cover on properly to keep the install very neat and tidy. Before putting the cover back on you can reconnect the battery and prime the fuel system to see if you have correctly reinstalled everything. The new Walbro fuel pump will be substantially louder than the OEM pump, this is normal.
Lastly put the cover back on and screw back in the X4 Phillips screws. These don’t have to be too tight, and they are actually threaded into plastic plugs that can strip easily.
Well there you have it, you have just installed a fuel pump. I know a lot of you reading are wondering why I did a write up on this. I’ll explain… you see, I document everything that I do to any car I work on because I can remember what is was like when I first started working on cars, and what it was like not knowing exactly how to do stuff. For some of you this may seem like a very basic thing to do, and if you’re one of those people then I’m happy for you because you know the basics of working on cars. However there are also many people that aren’t sure how to do this and I want to make sure they can learn how to do it for themselves, and feel the thrill of completing a modification (or even just replacing a bad fuel pump to get their car running again) Because there isn’t a more rewarding feeling in the world than doing something on your car and having it work properly.
Enjoy the read and enjoy the pictures, hopefully even if you’ve done this before you leaned something from this post. As always Thanks so much for reading, and make sure you get out in the garage this weekend and do something to your car. The weather is cooling off and its never been a better time to get out there. You can always ask me any question you might have about this post or anything else by commenting on this post below, Emailing me at Billy@functiontheory.com, or just DM me on Instagram @Functiontheory