This job requires a lot of patience and you really want to take your time to do it properly so you don’t have to do it 2 or 3 times. Don’t set deadlines for yourself. Prepare for a few days without the car so you aren’t rushing. It is possible you can do this in a single day if you have all materials prepared but again, rushing can create problems.
There are 4 main challenges with doing this job that can create issues:
1.) The fuel pump assembly has lines that can be easily kinked as you maneuver the hose in and out of the driver side of the tank.
2.) You will introduce debris into the tank and if you do not 100% clean it it can very easily clog up the mesh filter in the bottom of the pump assembly bucket.
3.) You can break the yellow nozzle on the fuel pump assembly, or the float (or other parts) if you try to force it in or out.
4.) Pump upgrade only: You can fail to use the proper type of hose from the pump to the top of the assembly, fail to create a leak-free seal, or kink this hose.
I will provide tips to help avoid these issues.
Things you will need:
(skimp on these things at your own risk)
1.) NEW Bosch Fuel pump assembly. Make sure you get the one for your proper VIN number and/or tank material. Plastic tanks are very clearly plastic if you look underneath the vehicle. Use a new assembly even if you are upgrading as the old assembly likely has a brittle hose and can very easily kink.
2.) Go ahead and buy a new sending unit too. They are cheap and you’re not going to want to go back in here.
3.) Buy the eBay fuel pump hatch removal tool for our cars. I think it is well worth the $35.
4.) Welding wire, sturdy string or similar to attach the pump assembly hose to the snake.
5.) An air compressor with blower nozzle
6.) A shop vac set up for dry use and step-downs to a small, flexible hose around 3′ long (old garden hose works great)
7.) A hand-operated transfer pump (cheap at most auto stores)
8.) Empty gas can – 2.5 or 5 gallon
9.) A cell phone to take flash video and see what you are doing in the tank.
10.) Clean microfiber rags and 91% isopropyl
11.) Something to attach the rag to to reach the edges of tank
12.) Good lighting – small flashlight and a headlamp work great
13.) An assistant for the moments you need to fish the hoses out of and back into the tank
14.) Fuel resistant nylon/latex gloves
15.) Clear safety glasses
16.) Small flathead screwdriver (pocket size)
17.) Shop rags or paper towels
18.) Synthetic grease to lightly seal pump hatch o-rings
19.) A small fire extinguisher ($20 at auto parts store and can mount in car after for peace of mind.) ((DO NOT skip this and risk burning up your car, garage or self.)
20.) Paper towels to soak up any gas spills
21.) An electricians snake or straightened out wire clothes hanger (or similar). If using a wire hanger, bend it into a nice wide “C” shape using pliers and hook one of the ends over twice so you can attach wire to it and it will smoothly navigate the tank.
If upgrading pump:
22.) Proper flex hose to go from pump to top of assembly:
Buy: “8mm x 8mm x 220mm Corrugated Flexible Hose Line”
DO NOT use the one that comes with the pump. It is too short.
P.S.: You may want to get 2 in case you ruin one.
23.) Heat gun
24.) Upgraded pump of your choice (of course)
25.) Red and yellow paint markers (like metal fabricators use – available at hardware store)
26.) Work gloves that resist some heat
27.) Silicon spray lubricant
28.) Hose clamps to fit flex fuel line (usually included)
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Walkthrough:
Skill level: Intermediate to challenging
NOTE: You are dealing with a highly explosive and flammable fuel. Take extreme care to isolate yourself from potential sparks, static, smokers, etc. Ensure battery is disconnected. Discharge static on the outside of the car multiple times as you enter and exit the vehicle. Keep the car and work area well ventilated. Do this job at your own risk!
1.) Run the car as close to an empty tank as possible.
2.) Park the car somewhere you are happy to leave it for a few days if you must. Park where you can easily access the interior from both rear doors and the hatch.
3.) With key in ignition, slide front seats all the way forward.
4.) Using a 10mm wrench, disconnect the negative battery terminal and tuck it away so it cannot reconnect. Remove the forward-most cargo area flooring (wagon).
5.) Remove the rear seats completely. I will not detail this as you can find it elsewhere, but basically flip the lower cushions forward and carefully pry red plastic to remove. The side bolsters pull out with some force. The rear cushions have a number of bolts and two airbag connectors to remove. The larger seat has a metal rod that slides into the smaller seat. I am working off a wagon, so sedan may be somewhat different?
6.) Remove the foam insulation cover.
7.) Time to clean! Move as much out the way as possible and vacuum and wipe down everything you can. Your goal is to keep this whole area free of debris as you work. It will easily go inside the tank. Clean the entire back area – the top deck, between seatbelts, everything.
8.) Remove the metal hatch covers – 4 10mm nuts each.
9.) Pop your hood and locate the Schraeder valve (just like a tire) on the left side of the fuel rail area (to the left of the forward-most engine cover). Ensure your engine is cool. Wearing safety glasses, place a rag beneath the valve area to catch fuel. Cover the top with a rag to keep fuel from spraying everywhere. Depress the pin using your pocket screwdriver until all fuel pressure is released.
10.) Returning to the fuel pump access, protect the top of the fuel pump assembly with rags and press both sides of the fuel lines to release them and catch fuel in the rags. Unplug the wiring harness to the pump assembly using the screwdriver on the tab and pull the harness upward. You can carefully tuck the fuel line connectors out of your way by pushing them gently between the metal body and the fuel tank until you find a place they like to stick.
11.) Time to clean again. You’ve just opened up the dirtiest portion of the tank area – if you look carefully you can see daylight between the tank and the body. This means road debris is always able to find a way up to this hatch. Vacuum and brush thoroughly. Use compressed air to blow everything out. Use rubbing alcohol and soapy water if that helps. Try to get this as clean as possible and it will save you headache later. No matter what you do though, you will likely still drop a little debris into the tank. That’s OK – we’ll get it soon.
12.) Using the special fuel pump removal tool and a ratchet, remove both rings. Clean the rings and their threads thoroughly and set them aside.
13.) On the driver side, pull up gently on the sending unit. Use your flashlight and locate the yellow suction unit at the bottom. Depress the tab to release it. Next unplug the small wiring connector and let it drop into the tank. Let this all rest in the tank where you can still see it. Remove the sending unit by carefully pulling it out of the tank. You should be replacing this, but if you decide not to, be extra careful not to bend the float.
14.) Using your transfer pump and gas can, drain this side of the tank as much as possible, moving around the tank and trying to suck up any debris you can spot while draining as much out of the low side (front) as possible.
15.) Use your snake and carefully connect it to the loop of the hose you disconnected from the sending unit. You want everything to be “smooth” so it doesn’t catch on anything when you feed it through, and it should be strong enough you can push and pull it without dislodging your wire from the hose. Test it to make sure.
16.) Move to the passenger side and gently pull the cup out a little but do not try to remove it yet. Use your transfer pump to empty the cup as much as possible.
17.) Locate the small metal float rod on the outside of the bucket that is attached to a plastic pivoting piece. I prefer to pop this out with the screwdriver as it makes removal easier. You can let it fall into the tank but you’ll have to retrieve it with a parts grabber later. If you don’t like that idea, you can leave it attached.
18.) Pull the pump bucket most of the way up until you feel a little resistance. Do not force it. Use your flashlight to find the float and the yellow hose attachment that likes to stick. If you tilt the bucket the right way it will come out without catching. Have a bowl ready to dump the remaining gas into so it doesn’t get in your interior.
19.) Now that the bucket is out, you need your helper to gently push the hose from the sending (driver) side as you guide the hose and bucket out. Do not force it. It is all about the angle. If you get a little stuck, back up and try a new angle or rotation of the cup. You can use your cell phone with flash in video mode to get an eye on the situation if you get stuck. Once the assembly is totally out, you can remove your snake completely so you can clean easily. It is easy enough to reroute later.
20.) Here is one the most important parts. With the old pump removed, it is time to thoroughly clean everything in and around the tank to 100% perfection. Start by using the transfer pump on the left side, again sucking up any debris you can find and remove ALL fuel from both sides of tank.
Once again clean EVERYTHING around the tank openings- the top deck, in between seatbelts, clean the ring that holds the pump in… EVERYTHING in the vicinity. It’s amazing how things can fall in as you’re working.
Clean the tank threads or you will just knock it in later when you are re-installing.
Use a clean microfiber rag, isopropyl alcohol and a flexible hardware grabber tool (or similar) so you can reach inside and clean all the tank edges. Use the small flexible vacuum attachment out of garden hose or similar so you can maneuver all over the tank easily. Use compressed air in between vacuum sessions to move debris around so you can see it. Use your hand in the parts you can reach. Sometimes you can feel grains of stuff that’s hard to see.
Alternate the above methods until everything inside the tank is impeccably clean. Use your cell phone to inspect both sides to ensure you are ready.
21.) Take your clean O-rings for the fuel access doors and apply a small amount of synthetic grease until lubricated. Apply a tiny amount to the threads of the special rings.
If replacing with OEM, skip ahead to step 30
If upgrading, continue:
22.) Dry all gas from the old assembly. Place it on a big, clean, well lit table, with the bottom of the bucket resting on the table. It is time to dissect this entire unit to ensure you don’t mess up your new assembly. First, unplug all wiring connectors to get them out of the way. Don’t worry about where these go – we still have the brand new unit. Pay attention to which direction everything is facing relative to the arrow on the top. Push down on the tabs holding the shiny metal pieces and pop the lid up a bit. Push on the tabs holding the float sensor in and remove it. Pop the 3 black plastic tabs out of the bucket and lift the pump assemblies out. Carefully use a box cutter or similar and slice the main pump hose connections off the pump and the end that goes to the “tophat”. Be careful to not gouge the plastic beneath or cut yourself. Remove that hose. This next part seems difficult but it really isn’t – lift out both pumps by pulling the bottom up at an angle. Don’t worry about the secondary pump hose – that is a flex connection. There! Now pop the main pump out of the black filter/holder by prying the bottom with a small pry bar or sturdy screwdriver. This takes some force. Don’t be shy. There! Now you’ve fully disassembled the fuel pump assembly. Now reassemble everything in reverse order for practice. You can reconnect everything except the hose you cut off obviously.
23.) Now clear off the table and switch to your brand new pump assembly. Take the paint markers and mark each connection in a way that will help you plug it back to the right spot. For instance, use yellow on the main pump connections(both ends). Leave a line that runs over the whole connector and plug so there’s only one way to plug it in correctly and have things align. Use a red line on the secondary pump, and a red line on the float wiring. Use yellow on the black small plug. Whatever works- you get the idea. This will just help you get the plugs right without worrying about them.
24.) As your paint dries, take a video of the assembly, slowly documenting how all the hoses and everything attach. This will be for emergency reference if you get confused later.
25.) Your brand new assembly probably has extra ground wires here and there. You can unplug those for now. One of them is attached to the main pump and your new pump probably doesn’t have a space for it. Go ahead and clip that one.
26.) Now, remembering your practice, go ahead and disassemble the new pump assembly, cutting the connector line from the main pump to the “tophat” as you did before.
27.) Get the work gloves, silicon lubricant, and the heat gun. Lubricate the connection on the “tophat” of the assembly. Heat up your new flex fuel line on “low” and rotate the line continuously in your gloved hand about 3 inches away for about 45 seconds. Be careful not to overheat by getting too close or you will melt your new line. You can tell the line is hot enough as it will develop a glossiness. Immediately push the line onto the connection ALL the way over the 3 barbs. If it doesn’t go all the way on, you did not heat quite enough. You can re-heat and remove to try again. Once installed, allow to cool then apply a hose clamp as a safety measure.
28.) Before applying the other end to your pump, you need to mockup the right position so you end up with a nice loop from the pump to the hat. Loosely mock up everything with the tophat facing in the right direction and your pump in the right direction for the black holder and bucket. Use your paint marker again to mark the proper hose placement for a clean loop. This doesn’t have to be absolutely perfect, just close. Now remove everything from your mock-up and work only with the pump and tophat again. No need to keep things looped, you can do that when you reassemble everything. Place your hose clamp over the flex hose and heat up like before and apply all the way over the pump connection.
29.) Reassemble the entire assembly, twisting the tophat to create a nice loop to your pump. Ensure all connections are solidly connected and black plastic tabs are fully snapped into the white bucket. Ensure all ground wires are reconnected except the one you snipped from the pump. Triple check that everything looks correct and everything is clean.
Reinstallation
30.) Check one more time to make sure in and outside the tank is totally clean of any debris. Make sure the tank o-rings are in the right position. Holding the assembly above the tank, visualize how you may rotate it as it is fed through and how it needs to end up with the arrow facing the rear of the vehicle. Thread your snake from the driver side to passenger side and securely attach with welding wire to the end of the hose as you did for removal.
31.) With your helper carefully pulling from the driver side, gently guide the hoses through. If you feel too much resistance, back up and try a different angle. Take your time. If you get stuck, use your phone again to see what is catching. Do not force it or you will kink the line.
32.) Once the sending hose is visible all the way on the driver’s side, carefully angle the bucket into place, using your flashlight to avoid damaging the float or yellow connector. Take your time and don’t force anything. Once partially installed, ensure the float is to the passenger side of the bucket before you push it all the way into place.
33.) Secure the main pump bucket down using the special ring.
34.) Install the sending unit/float on the driver side. Face the arrow toward the rear of vehicle. Put the float in first, then attach the yellow suction disc to the proper channel on the sending unit. Plug in the electrical connector. Push the assembly down and secure with the special ring.
35.) Tighten both rings while holding each unit to stay with the arrow pointing backward. This takes a bit of finesse to keep it from rotating on you. Get these fairly tight, but no need to overdo it.
36.) OPTIONAL: If you were experiencing problems from debris, you may want to flush the fuel line that goes to the fuel filter at this point. Use isopropyl and compressed air after disconnecting the main fuel filter below the vehicle. Then replace the main fuel filter with a new one.
37.) Reconnect the electrical connector to the pump assembly. Reconnect your fuel lines you tucked away earlier.
38.) DO NOT reinstall the metal hatch covers or your seats yet. First test thoroughly that everything works properly.
39.) Add about 3 gallons of NEW gasoline to the tank.
40.) Reconnect the battery.
41.) Turn the key to position II and you should hear the pump activate. Do not attempt to start the vehicle yet. Continue to prime the system several more times.
42.) Leaving the key in position II, check all fuel lines for leaks.
43.) Now start the car. It may take a few tries since the system was totally empty.
44.) Run VIDA to check for any error codes. Also check Fuel Pump Duty Cycle and Fuel Pressure under “Vehicle Communication” and “ECM”. Duty Cycle should be in the range of 35% and fuel pressure should be about 400kpa at stock idle.
45.) Go for a test drive before you reinstall seats, etc. If all is going well, add a little more gas. Drive to temp and then do a few pulls to make sure everything is good. I recommend a 20-30 minute drive not too far from home.
46.) Run VIDA again to make sure all is well.
47.) Reinstall seats and clear airbag codes in VIDA.
Enjoy your new fuel pump and clean fuel system!
P.S. If you still encounter issues, you should clean the front fuel line from fuel rail to filter; clean the fuel rail; and have injectors cleaned. If this does not solve your fuel issue, check Fuel Pressure Sensor and PEM.