Fuel Pump Replacement on 5th Gen Toyota 4Runner

This is a part of a lengthy diagnostic process when my car suddenly started to intermittently go into crank and no start mode. The issue was related to fuel delivery. Only that part was obvious, but what was causing it was a mystery. It took me 3 weeks to figure out the issue, but it all started with the most obvious thing - the fuel pump. That is what tow truck driver said when he towed the car to my house, "It is the fuel pump!"

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Fuel Pump Assembly Removal

Manual page: 2500




To correct way to replace the fuel pump on these vehicles is to drop the tank. With the amount of rust on the undercarriage of my car, I would rather not take that route. The second option is to enlarge the existing hole just enough to pull the fuel pump assembly out. This is the route that I chose to take.



When I was building my camper, I never considered that I would be doing these sort of repairs in the future, so I placed my electrical system right over the fuel delivery system. Not the best location, but it worked fine so far.



The size of the opening is determined by the location of structural components. I wanted to make the right side larger, but couldn't due to one of the structural members that passes under the body of the car. This meant that I had to enlarge in the opposite side where the harness is located.



It turned out that 5th Gen 4Runner fuel pump is not self-priming. Fuel pump is receiving only positive input with key in the ON position, but no negative input. With key in the START position, ECU sends negative input to the pump, which turns it on.



Since I didn't have Lisle 63000 Fuel Tank Lock Ring Tool, which I ordered later, I had to get creative and make something that would get the lock ring off.



I got the tool later and tested it in the existing setup. It worked perfectly and allowed me to torque the lock ring to correct specifications given in the manual. You have to press on the wrench really hard as you are torquing the lock ring, otherwise the tool is a bit wobbly.



The manual (pg 2503) says that the line in-between the lock ring indentations has to be between the two triangular marks that are stamped on the right side of the fuel tank.



I decided to make access door for the newly created opening. A thin sheet of metal worked fine. I secured it with several sheet metal screws around the perimeter.



To add additional protection, I taped the perimeter with Gorilla tape.



The door was then covered with original piece of carpet. Now I have access to the fuel pump at any time, and the tools to get the assembly out in case I need to change the pump on the road.

 

Good job and write up. Was your truck not part of the fuel pump replacement recall?

 

Fuel Pump Replacement
Manual page: 2415


This is what the entire assembly looks like once it is out of the fuel tank. To remove fuel sub-tank fuel pump and jet pump connectors have to be disconnected and jet pump has to be removed.



3 claws that are holding the fuel pump in the fuel sub-tank have to be detached from the claw holes.


The fuel pump is out.



I do not think it was necessary to remove the claw ring, but I decided to take it off anyway.



I found it easier to disconnect the fuel pump from the filter case by using two picks. There are a total of 5 claw holes that need to be detached from the claws.


Fuel filter is detached.



I found it easier to use a screw driver to push the pump out of the casing.




There are an o-ring and a fuel pump spacer inside of the casing. I had to remove o-ring with a pick after taking the fuel pump out.



Old and new fuel pumps side by side. I used BOSCH fuel pump. Fuel filter was pretty dirty after 185,000 miles.



Reassembly is pretty straight forward. Fuel pump harness is connected to the pump. Fuel pump is then inserted into the casing along with fuel pump spacer and o-ring.


The claws on the fuel filter case are pretty stiff. The easiest way that I found to put it all together is by placing one of the claws into a claw hole and then placing the rest one at a time.



Pulling the claw hole with a pick helped in the process.



Everything is back in place.



The ring that I removed in the beginning is back in place as well. I think it is easier to work with the pump without it.



All the dust was cleaned out from the fuel sub-tank. With this much dirt, I think it is a good idea to replace fuel filter once in a while. I am still not sure why Toyota decided to remove post-filter that was included in previous generations. 3 filter fuel filtration system (pre-filter, post-filter, injector filter) would be ideal.


Fuel pump is placed in the fuel sub-tank.






Fuel pump and jet pump connectors are reconnected and jet pump is reattached to the fuel sub-tank.


Fuel pump assembly is ready to be reinstalled into the fuel tank.

 

Not sure. It is 2010 model. How do you check if it was?

 

Fuel Sender Gauge Assembly and Fuel Gauge

After I reconnected everything I noticed that my fuel gauge was at zero. It appeared like I solved one problem, but created another one.



I checked if the fuel sender gauge assembly was sending the signal to the ECU. Resistance reading showed that I had 1/2 tank of gas. ECU was receiving inputs.



I fired up Torque Pro OBD app on my tablet and checked fuel level. it was showing that I had 10.4 gallons of gas. I was confused for some time, and then saw that fuel gauge readings started to slowly climb up. After I finished with my lunch, the fuel gauge on the dash was reflecting correct information.

 

Fuel System Diagnostics Summary

In the end, it turned out that fuel pump didn't have to be replaced. Here is a short summary of diagnosing problems with the fuel system that I followed.

Fuel Pump

Power

• Checked EFI fuse.
• Checked EFI relay.
• Checked C/OPN relay.
• FP is receiving positive input with key in the ON position, but no negative input. With key in START position the pump is receiving both negative and positive inputs.

Pressure

• Fuel pressure is 50 psi with key in the START position.
• Performed fuel pressure leak down test
  - Fuel pressure is 36 psi with engine not running. The pressure doesn't drop.
  - Rules out faulty check valve at the pump, leaking injectors, and fuel pressure regulator.

Fuel Rail and Injectors

• Did a listening test on 5 injectors (couldn't reach the other one). Every one of them clicks.
• Checked for misfire codes.
• Did injector pulse test
  • There are good inputs from the ECU.
• Checked injectors (resistance, operation)
• Cleaned fuel rail and injectors

Fuel Trims

• Fuel trim analysis was performed.
• No drastic changes were found in fuel trims on both of the banks.

 

https://www.nhtsa.gov/recalls

Your 2010 probably wasn’t included but you can enter your VIN on the attached link to see.

I think the fuel pump recall affected 2017-2020 models. There was several threads on this a few years ago.

 

Have you found out what the problem was with the crank no start?

Also, what manual are you using?

 

I use 2010 Toyota Manual that I found on one of the forums. https://www.mediafire.com/?91cliu5r6nb38

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Making long story short, I found what the problem was. It was the immobilizer chip in the key. I found out about it in a very dramatic way when I was on the edge of mental breakdown trying to start the car that again would not start. I forcefully turned the key in the ignition and the plastic part with the remote and transponder chip broke off from the metal key. When I got another key and inserted it into the ignition switch, it worked fine.

I returned home and glued the metal part of the key back in place. The car still would not start with the old key, producing the same symptoms as before. It would start with a new key without problems though. I went ahead and cut out transponder chip from the old key and taped it next to the ignition switch. With it in place I tried to start the car with the old key, and it worked fine. With the transponder chip in the casing, the key would not work. Interesting...

I spent two weeks trying to diagnose the cause of crank and no start issue that went from permanent to intermittent, looked at every system in the car, changed a bunch of parts, and never even considered that the problem was a malfunctioning transponder key.

The funny thing is that if I didn't get mad and broke the casing off of the key, I would have never figured out what the problem was.

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I installed Techstream and got myself a cable that allows you to run much better diagnostics than with an OBD app. It shows you all the information that you need to diagnose more in-depth problems with the car (Immobilizer status, Fuel pump status, etc). I couldn't get this sort of information from Torque Pro, but could only get the basics. It also allow you to reprogram remotes, transponders, tpms sensors, etc. Very powerful tool to have in your tool kit.

Replacement of parts was done as the last resort strategy. I simply didn't know what to do, since the computer was showing that everything was in top working condition. I guess it was a good thing in the sense that I turned the car inside out, acquired new skills and tools, cleaned up a bunch of things, and made a bunch of modifications on the way.

 

Good to know. No recalls on mine.

 

Thank you for posting the resolution to this problem. It will likely help many others when this happens again to someone else.

 

Wow that all sounds incredibly frustrating! You’d think transponder signal failure would show up as a code on even the simplest apps. I seem to recall my old 99 Accord had a light on the instrument panel that indicated the status of the key transponder signal. I remember it was a little green light w/ a key symbol on every start. It was an obvious enough light that helped remind you that there was a key transponder. However, not sure what the light would have done if the transponder failed.

I haven’t noticed anything like this light on the instrument panel of my 4runner. There was somebody else that recently posted about a problem that turned out to be transponder related, so I bet it’s not obvious when there is a transponder failure. It should be! Even a “no key signal” error message wouldn’t have been that hard to implement.

By the way, thanks for the link!

 

The immobilizer strikes again.

 

Do you have a link to the other post, by a chance? Would be interesting to read through it.