replacing fuel pump

W

Wayne

New member
1) Has someone posted a procedure for this operation somewhere?
2) What else will I need besides the pump for my 97 V6? Strainers, O-rings, gaskets, whatever? I will replace the filter while I'm at it
3) Rock auto lists several pumps-any of them just as good for less? I don't want crap but I'm on a very tight budget with my job ending in 8 weeks.
 
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I see Denso in there, that's likely the OEM pump and what I would choose. I suspect if you go for one of those $30 pumps you'll get what you pay for. How soon do you wanna replace it again :)?

I haven't done the fuel pump on my '99, but my '85 has a hatch under the rear seat that gives access to the top of the fuel tank and makes swapping the pump a very painless job. If your 3rd gen doesn't have that hatch, then you'll probably have to drop the tank. That entails removing the skid if it's there, disconnecting the filler hose on the side, unplugging the wiring harness, and disconnecting the fuel and return rails leading to the engine bay. Then drain whatever gas is in there, then drop the tank. But if you're lucky, Toyota was smart and kept that access hatch under the rear seat. Even if you don't spill a drop, you're going to get fumes everywhere, so wear clothes you don't care about and get a set of disposable nitrile gloves. If you don't have the FSM for your truck, get a Haynes or Chiltons manual, they're like a whole book full of forum writeups. :)

I haven't read your other thread, are you sure the fuel pump is bad?
 
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Like KV said, only buy the OEM part.

I'm still on my original fuel pump and so are lots of others.

Are you sure it isn't your FUEL FILTER that needs replacing?
 
KidVermicious said:
I see Denso in there, that's likely the OEM pump and what I would choose. I suspect if you go for one of those $30 pumps you'll get what you pay for. How soon do you wanna replace it again :)?
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Well at 240K I figure I get another 100K and then fuel pumps become the least of my problems. So if I thought one of the 60 pumps would get me there I'd be OK with that.

I haven't done the fuel pump on my '99, but my '85 has a hatch under the rear seat that gives access to the top of the fuel tank and makes swapping the pump a very painless job. If your 3rd gen doesn't have that hatch, then you'll probably have to drop the tank. That entails removing the skid if it's there, disconnecting the filler hose on the side, unplugging the wiring harness, and disconnecting the fuel and return rails leading to the engine bay. Then drain whatever gas is in there, then drop the tank. But if you're lucky, Toyota was smart and kept that access hatch under the rear seat. Even if you don't spill a drop, you're going to get fumes everywhere, so wear clothes you don't care about and get a set of disposable nitrile gloves. If you don't have the FSM for your truck, get a Haynes or Chiltons manual, they're like a whole book full of forum writeups. :)
Click to expand...

There is indeed an access hatch! But its several inches too small to get the pump out! This is the dumbest design ever for Toyota except for their crappy sun visors. Might be time to enlarge that access hatch a bit.

I haven't read your other thread, are you sure the fuel pump is bad?
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I've got 12v to the pump and nothing comes out the line before the fuel filter when its cranked with gas in it. I'd love to find another cause but I'm about out of places to look.
 
Which wires are you getting the 12 volts. The fuel level sender also uses 12 volts, just be sure it is the pump wires that you are getting the 12 volts on.

I used the $115.00 Denso from Rockauto on my 99 and it came all you need to do it right. Its a lot of work to have to do it again any time soon.

Watch out for the small wire harness that runs across the top of the tank on it's way to the rear of the truck because it is attached to the top of the tank. As you lower the tank you can reach up and detach it.
 
Wayne said:
You mean you haven't been criticized for not doing a preemptive pump replacement?
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Probably a bad idea to say this but I have a 1990 Mitsubishi truck that I bought new and the fuel pump in it has 280,000 miles and 23 years on it.
 
Wayne said:
You mean you haven't been criticized for not doing a preemptive pump replacement?
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No I haven't because it is not considered a part that requires preventative replacement. In fact I hardly recall seeing any threads about Fuel Pump Failure on this forum. If it was a common issue there would be plenty of others.

Question: Have you replaced the fuel filter yet?
 
Good question. There is a gray plug with 5 wires that plugs into the tank. IIRC one of them had 12v with the ignition on.

Where is the sender wire? Would it be part of that same plug?

There was a second harness with 4 wires that heads further back but feels like it connects to something I can't see just in back of the access hole. Maybe its the attachment you speak (or maybe its the sender?). That harness has a connector on it so I can just disconnect it if I drop the tank.



mmml4 said:
Which wires are you getting the 12 volts. The fuel level sender also uses 12 volts, just be sure it is the pump wires that you are getting the 12 volts on.

I used the $115.00 Denso from Rockauto on my 99 and it came all you need to do it right. Its a lot of work to have to do it again any time soon.

Watch out for the small wire harness that runs across the top of the tank on it's way to the rear of the truck because it is attached to the top of the tank. As you lower the tank you can reach up and detach it.
Click to expand...
 
Then how do I figure out which one has 12v? I'm an electricity class drop out. I'm pretty sure it was the middle one on the side that had 3. The plug looked like

i i i
i i
 
Then I need to know which one is getting 12v. IIRC its the middle one on the side of that 5-prong connector that has 3. I cant read a schematic (nor do I have one) but maybe someone else does/can.





mmml4 said:
The sender wires and the pump wires are all in the same connector.
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In the 97 4R wiring diagram book(purchased used for $75...gack!), the blue wire with orange stripe is the 12V+ lead from the circuit opening relay to the fuel pump. That's what the book says--I haven't seen the wire myself yet.
 
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Wayne said:
Good question. There is a gray plug with 5 wires that plugs into the tank. IIRC one of them had 12v with the ignition on.

Where is the sender wire? Would it be part of that same plug?

There was a second harness with 4 wires that heads further back but feels like it connects to something I can't see just in back of the access hole. Maybe its the attachment you speak (or maybe its the sender?). That harness has a connector on it so I can just disconnect it if I drop the tank.
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dude, almost everybody here over analyzes diagnosis. If you don't have fuel coming out of the pump pre fuel filter, and have power to the pump, you have a bad pump. It's always a good idea to replace the fuel filter as well, but for the love of god, diagnosis doesn't need to be that complicated for something as cut and dry as your issue.
 
The blue/orange wire is not getting any juice with the ignition on (this is not cranking, as I'm by myself now). The one getting 12v is the black/red wire. Maybe I need to hunt for that supposed underdash relay I can't find.
Does the relay show in your diagram?

Edit: the solid yellow wire shows 5-6v. What is that one?

pluton said:
In the 97 4R wiring diagram book(purchased used for $75...gack!), the blue wire with orange stripe is the 12V+ lead from the circuit opening relay to the fuel pump. That's what the book says--I haven't seen the wire myself yet.
Click to expand...
 
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You will only have voltage to the pump while starting (starter turning engine over) and while the engine is running. The fuel pump will not be running with the key in the on position without the engine running.

Lighten up blackcat he doesn't understand the circuit and has yet to determine if he has voltage on the pump.
 
I don't under stand the circuit, you're right, and thats why I'm proceeding carefully. I don't want to make a big problem out of a small one. Besides I can't get the pump for at least another week so there is no rush anyway.

So help me understand the circuit, if you would-why does the pump need the car turned over to get voltage, but it keeps running when the ignition is released once the engine starts? I guess it makes perfect sense though, no reason for the pump to run when the car isn't. But I still don't get how it can receive voltage after it starts and you release the ignition.


mmml4 said:
You will only have voltage to the pump while starting (starter turning engine over) and while the engine is running. The fuel pump will not be running with the key in the on position without the engine running.

Lighten up blackcat he doesn't understand the circuit and has yet to determine if he has voltage on the pump.
Click to expand...
 
I don't know if this is true for the 4R or not, but on some vehicles, the computer needs to see the oil pressure sensor report adequate pressure before it will the latch the fuel pump on. This prevents engine damage in case of low crankcase or bad oil pump.

Crank engine
Fuel pump turns on
Oil pressure = good, leave fuel pump on
Oil pressure = not good, turn fuel pump off

Hope that was clear?

Aaron
 
Yes, that makes perfect sense.

Today I had someone crank it and I still had no voltage at the blue/orange wire on the fuel pump connector. As I mentioned (perhaps in my other thread) I found what I believe to be the fuel pump relay near the fuse box under the lower dash, and it seems to be operational. It clicks when placed into the EFI relay location (they are identical OEM relays-although every parts store tells me they should not be). But it does NOT click in its proper location. So either I have some other wiring problem, or I found a relay that isn't for the fuel pump.
 
My understanding is the ECM monitors the crank position sensor, if the ECM does not see the crankshaft rotating it will not allow the fuel pump to run.

Lets say you were in a collision and the engine stalled for whatever reason and the fuel line was broken in the engine compartment leaking fuel, you would not want the fuel pump to continue to run in case of a fire.

It's not as simple as it seems.
 
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