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Discussion Starter #1
Hello,

Hoping that someone might have an idea to this issue. My wife's 2002 has had the third fuel pump fail in about 9 months (I still need to test tomorrow during daylight, but almost positive since I don't hear it priming). Car has a smidge less than 99k miles I believe.

First, the OEM pump failed. Then I bought a $10 pump off eBay. It failed within about 3 or 4 weeks. Then I bought a Bosch from Amazon. Tonight it failed.

The fuel sender unit works because it displays the correct amount of fuel. But the engine just cranks and like I said, no sound of the pump activating when the key is in the on position.

Am I just extremely unlucky or is there somewhere else I should look? Thank you for any advice you can offer!
 

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What testing have you done to prove it's the pumps that are failing not something in the circuit powering them?
 

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Discussion Starter #3
Hi Dr. Dyno, thanks for replying. That's a good question. When the first or second one went out, we did test relays and fuses to make sure they were working and/or pulling the right voltage. I know we checked under hood and I believe also there was a relay of some sort under the dash to look at.

For what it's worth, after cranking a bit more the car was able to start up. It tried to start, then sputtered, then started fully after three more tries. It drove very well, both at low speeds, acceleration, and on the highway.

Not sure what would cause that...the car is driven at least a bit almost every day. Today my wife only started it to back it out of the garage onto the driveway (not an incline).
 

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It wouldn't surprise me at this point if none, especially the two replacement pumps are bad. You could easily test them by applying 12V with some clip leads at your battery. On the car the test is a 12V test light connected to the pump plug terminals to see if it's actually getting power when it doesn't run.

One reason I mention this is the fuel pump on my '06 RAV4 was starting to make a whining sound. I figured it was starting to fail so I bought an eBay one and was planning on installing it. I posted the problem and JuneBug said it might be the fuel pump resistor instead. I bought a new one online from a Toyota dealer, installed it and haven't heard any whine since.

Of course mine is a 4.3 not a 4.2 and you have the opposite problem wishing yours would whine, but the point is the cause could very likely be something else and until proper pinpoint tests are done you'll probably get pretty good at changing pumps. :wink:
 

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I'm 138k on the OEM pump, and very surprised to hear this. Are you sure the replacement Denso pump is a real Denso? Sounds like you bought failing/garbage pumps given your descriptions, but the harness that connects to the pump, do you notice any signs of overheating? Any connectors that could be damaged/melted/etc?


I want to think your pump is burning out because of a compromised component connecting to it...just my two cents.
 

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Discussion Starter #6
Thanks for the reply. I'm not sure what the first pump was; it was a Chinese model. The second pump was a Bosch OEM replacement. But Bosch is a well known brand I would not think there would be any issues. Plus, since the car eventually did start, it seems a little weird because I thought fuel pumps were all or nothing sort of deals.

We did have to put a new wire connector onto the housing/harness with the original pump. However, my dad who helped with this part is familiar with this sort of rewiring as he does it frequently in his line of work, so he used the proper materials/heat sheaths, etc. The fuel gauge was registering too so it would be a little odd (I think, but not sure) for the pump to not work but the sending unit to read accurately.

The car also started up this morning with no problem when I tested it before work. My wife started it up this morning a bit later and successfully made it to her destination.

Kinda strange!
 

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Sounds like you're in OK shape with the replacement BOSCH unit. What wire connector did you have to put on? Like, on the factory pump, did something overheat with a connector? Or a harness?


I've seen(not on these cars) situations where headlight harnesses for example overheat frequently due to their location and melt connectors. People replace connectors when the problem is the OEM harness or something going to it due to location or the elements. I'm thinking you might have to keep an eye on the fuel pump harness and look for any signs of degradation.
 

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Discussion Starter #8
We had to put on the two-prong (or whatever you want to call it) that connects from the housing to the pump itself; it was included with the Chinese pump because the connector head was slightly different. It also worked for the BOSCH unit though.
 

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... The fuel gauge was registering too so it would be a little odd (I think, but not sure) for the pump to not work but the sending unit to read accurately.
The fuel pump and the gauge are on separate circuits so you can't judge by that. The power for the gauge comes directly from the key circuit whereas the pump power goes thru one or more relays and a safety circuit that shut it off in an accident. That's why I say testing for power at the pump is necessary.
 

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Discussion Starter #10
Sure, I can definitely try that this evening. Aside from 12v, what else would I look for? And any idea what else I might look for since it was intermittent?
 

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Intermittents are the hardest electrical issues to diagnose. You really need a circuit diagram to trace the power loss, if that's what it is, backwards to the relays, fuses and battery.
 

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Have you put a fuel pressure gauge on the system to verify pump pressure while cranking? Pumps need to develop a certain cracking pressure so the injectors can fire... voltage drop is related to this as well...
 

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Hello,

The fuel sender unit works because it displays the correct amount of fuel. But the engine just cranks and like I said, no sound of the pump activating when the key is in the on position.
On my 1st gen Rav4, turning on the key does not turn on the fuel pump, the ECU needs to have a signal from the crankshaft sensor or the starter, to power the pump.

When did you buy the Bosch pump?
I see on the RockAuto.com page that before 10/1/16 the pumps have a 12 month warranty and if you bought after that date the warranty is lifetime.
 
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