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2000 Ls400 How To Replace Fuel Pump

David P

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I have found answers to previous questions without joining the forum but can't seem to find instructions on how to change the fuel pump so.... here's my situation:

About a year ago I was sitting in a parking lot with the car idling for some time while I was finishing a call on my cell phone when the car started idling roughly, acting like it was going to die. I shut it off and tried to restart; the first time I tried the car acted like it was going to start and then promptly died. Subsequent attempts to start seemed to bring the rpms to around 5-600 but the car wouldn't start. I had run the car down to within 20 miles of range or so, so I figured I wasn't getting enough/any gas into the system. Put 5 gallons in, same result. By the time my ride was able to pick me up, around 2 hours later, the car started and ran like a champ. I figured I had some sort of blockage in the fuel filter from a piece of debris on the bottom of the tank and when pressures were relieved a bit from sitting, the debris was cleared (no idea if the system works like that, but that was my thought). I drove the car with no problems whatsoever until this week.

Again, I was parked in a lot finishing up a telephone call and the car had been idling for some time. The symptoms this time were nearly identical to those a year ago; idled roughly, I revved it up a bit and shut it off. When I restarted, I got rpms to around 1500 but the engine promptly shut off. Restarts were also identical; got to around 500 rpms but no ignition. Seems like it is starved for fuel, although this time I have around 1/2 tank. I let it sit for a few hours but it wouldn't restart this time so we towed it to a local repair center.

The next morning the service center called and indicated that the car started fine although the fuel injectors and throttle (body? I can't remember the term) appeared to need cleaning. I had them clean things up but when they attempted to restart the symptoms returned. Mechanic tapped on the fuel pump and the car started ok. When I went up to pick the car up, it wouldn't start.

I do apologize for the lengthy read but wanted to provide as many details as possible. I believe I need a fuel pump and am looking for instructions on how to change it out but if you believe it may be something else, I am open to any suggestions.

BTW, mechanic wants $390 for fuel pump replacement. Parts: Denso pump & strainer $250; labor $105 plus tax and shop supplies.

I don't mind paying someone to work on my vehicle but I can get a Denso pump for a little over $100 and I don't believe this is the most complicated repair job one can do.

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Hello and welcome to the LOC.

The fuel pump is accessed by removing the rear seat base and upright section ( see link below) and then removing the plate/seal on the exposed gas tank.(Shown as the silver disc in the center of the last tutorial picture)

Remove the pump disconnecting the feed pipe and electrical connection.

Take obvious precautions like disconnecting the battery before starting work and ensure you take care of the fire risks present once the tank is opened.


Curious to know how your mechanic tapped the fuel pump hidden behind the rear seat?

Did the shop not check the fuel pressure when the car was in?

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I would have to agree that for $105 in labor, there cannot be a lot of work in changing the fuel pump. However, you do live in Michigan and it is January. Do you have a heated garage? If not, it might be worth hiring the mechanic especially since he helped to diagnose the issue.

If you decide to DIY, the first answer here sounds reasonable:


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Thanks for the replies.

Steve: Thanks for the link and asking a couple of good questions. I suppose since the tank is rigidly in place, tapping on the bottom of the tank would have the effect of tapping on the pump. Not sure. I'll ask them about the fuel pressure.

Landar: Thanks for the link.

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