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95.5-2004 Tacomas & 96-2002 4Runners 4th gen pickups and 3rd gen 4Runners

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Old 07-20-2013, 07:59 AM   #1 (permalink)
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fuel pump has power but truck won't run unless pump hotwired

I have just bought a 2000 Tacoma 3.4 220,000 miles from my little brother(he needed money), and it doesn't run.

He said that he was losing power while driving for a while and then he went out to start it and it wouldn't fire up.

I initially just sprayed starter fluid in it and it fires then dies. So I thought Fuel problems.

I checked the power to the pump, it has power when you crank the motor. Just for fun I hotwired the pump from another battery and the truck fired right up. Ran great. But will only run if hotwired not under it's own power. The pump seems to run louder when it is hotwired don't know if that has anything to do with it.

I have also checked both fuel relays (EFI and the other one by the steering column) Both operate perfectly and have power in the right places.

I also cleaned the MAF with MAF cleaner. I also cleaned the IAC, found some junk in the IAC that was in the little gap that rotates. Thought this could have been impeding the operation of the truck but it still does the same thing.

Also replaced the fuel filter.

I'm stumped. I have searched the forums for an answer and couldn't find anything. Any help would be greatly appreciated.
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Old 07-20-2013, 08:36 AM   #2 (permalink)
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Red face

I take it the MIL is not on??

This should be throwing a code.

Can you see any damage to the wires going to the pump the whole length .from the circuit opening relay

The MAF is getting the signal from the ECM??

** Check the circuit opening relay that is what powers the fuel pump **

** The part that really sucks is it up behind the steering wheel behind the dash never having had to find mine I am not real sure just where.

Which goes to the circuit opening relay when the contacts close it goes to the fuel pump.

There are Two coils in the circuit opening relay if the run side has burnt out that is why it dies after a few seconds.

Just how are you jumping the fuel pump at the connector??

If you need more help PM me I should be able to help
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Old 07-20-2013, 09:51 AM   #3 (permalink)
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I checked the Circut Opening Relay. it opens and closes with power to the starter side.

The truck will only start with ether for a couple seconds. With no ether it will not fire at all.

I hotwired the pump and the top of the tank by taking off the harness and applying positive to where the blue wire would connect and negative to where the white/black would connect as per wiring diagram.

The thing that gets me is that I have power at the pump when I crank the truck and for a few seconds after that, but it won't run. Then it runs when I hotwire the pump??? Doesn't make sense

i checked the continuity from the blue at the circuit opening relay to the pump and it is perfect.

I have have a code reader and it has not thrown a code yet,

How do you check if the MAF is getting signal from the ECM?
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Old 07-20-2013, 03:18 PM   #4 (permalink)
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Are we dealing with the Federal or California emissions package there are some differences .

At no time does the engine start without using starting fluid when the fuel pump in not hotwired.

But you do read battery voltage while cranking

your not trying to start this without the air intake hooked up

The MAF has to see enough air flow to send the signal to the ECM to show the engine is running

If the engine is not running the fuel pump does not stay running.

feels like more issues then just the fuel pump one.

Could be something simple as a corroded connection or loose one

This is one it is nice to be up close and personal

Be good to post your location help could be close at hand.

Last edited by wyoming9; 07-20-2013 at 03:20 PM.
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Old 07-20-2013, 06:21 PM   #5 (permalink)
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Quote:
Originally Posted by Shawnjames View Post
I checked the Circut Opening Relay. it opens and closes with power to the starter side.

The truck will only start with ether for a couple seconds. With no ether it will not fire at all.

I hotwired the pump and the top of the tank by taking off the harness and applying positive to where the blue wire would connect and negative to where the white/black would connect as per wiring diagram.

The thing that gets me is that I have power at the pump when I crank the truck and for a few seconds after that, but it won't run. Then it runs when I hotwire the pump??? Doesn't make sense

i checked the continuity from the blue at the circuit opening relay to the pump and it is perfect.

I have have a code reader and it has not thrown a code yet,

How do you check if the MAF is getting signal from the ECM?
Check continuity on the other wire for the fuel pump circuit. It's a circuit so it has to make a complete loop for the electricity in order for the pump to run. You might have power down to it, but if the power can't complete the circuit back the pump still won't run. It sounds to me like the power for the circuit lost its path back to ground.
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Old 07-20-2013, 07:26 PM   #6 (permalink)
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I bet it runs louder with it got wired because you have more voltage/amps going to the pump than through the circuit on the truck.
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Old 07-24-2013, 10:08 PM   #7 (permalink)
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Any luck getting this sorted ??
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Old 07-24-2013, 10:08 PM
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96, fuel, power, pump, running, start, tacomacircutopeningrelay, toyota

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