I replaced my fuel pump about two years ago and.

Tiny
JIMEL48
  • MEMBER
  • 1996 TOYOTA TACOMA
  • 114,000 MILES
I replaced my fuel pump about two years ago and truck ran good. I have put about 1000 miles on it and I am having the same problem again. All relays and fuses are good, however I do not get any power to my fuel pump until I turn the engine over. The male connector (for the positive blue wire and ground white/black stripe) at the fuel pump have continuity. Does this mean a short?
Saturday, October 27th, 2012 AT 6:06 PM

5 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Check to see if the relay is getting a signal from the pcm I have an arrow pointing to it. Check the ground in kick panel and check the junction block to see if everything is going through it. If they have continuity I would rule out a short. The black/white wire goes to the starter relay which there is a fuse in between if any of that is a poor connection you won't get power. The black wire going to starter relay gets power directly form ignition switch so check that stuff.
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Saturday, October 27th, 2012 AT 6:18 PM
Tiny
JIMEL48
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  • 32 POSTS
I could not find your arrow but I checked Toyota manual and there should be resistance at fuel pump connector, it was within spec. Fuel circuit relay is kicking off when I turn the key off (2 to 4 sec) and pressure falls to zero. I have swapped out efi relay and circuit relay and checked efi and ign fuses. I am thinking starter switch, control module, or wiring connections. I was hoping you could give me a road map to isolate problem without going thru whole system. Truck is very hard to ignite and will not keep running, fuel pressure cranking is about 28 psi.
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Saturday, October 27th, 2012 AT 7:18 PM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
If you test the fuel pump wires for continuity across the fuel pump terminal, it must show continuity.
Fuel pressure dropping to 0 when ignition switch is turned off means there is a pressure leak and it could be the fuel pressure regulator or intank or even the fuel pump itself as the check valves are leacking. This explains the difficulty in starting.

At fuel pressure regulator return hose, clamp it to prevent fuel from returning and if pressure holds, the pressure regulator is bad. If pressure still does not hold, you would need to check the fuel pump. Quite often the hose between the fuel pump and housing ruptures resulting in pressure leaks and bing in-tank, you would not notice any fuel leaks.
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Saturday, October 27th, 2012 AT 7:34 PM
Tiny
JIMEL48
  • MEMBER
  • 32 POSTS
Sorry it took a while to get back to you. You were right the the hose clamps did not hold at the pump. Truck is holding pressure and starting fine however the pump is still not activating with the key on and I would like to get it right with your help. I have continuity with wht/blk, blue wire at circuit relay connector and wht/blk, blue wire at fuel pump. With key on I have 12v at 7.5 ign fuse and wht/red wire at relay connector. No other wire at relay has power with key on. I power tested relay and seemed to click over fine. Also had access to another relay with no change. Looking at the manual it seems the ecm grn/yel wire might power the fuel pump with key on. Anyway I wanted to get your opinion before running it down any farther. Thanks for your help.
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Saturday, November 10th, 2012 AT 11:14 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
I screwed up on first answer by not sending a diagram that I had sorry. The white/red wire should have power so look in junciton block tosee if it has power there eitehr one side or the other. And the green yellow wire comes form the pcm. There is a brown wire by the throttle ody that goes to ground for pcm see if that is broken or corroded. I took this from a 2.7L engine as you didn't state what motor you have. So if you have a 3.4L it may be a little different also dont' forget to check efi relay as that directily ties into fuel pump at junction block center of dashif you have a similar one try replacing it with another to see if makes a difference. Also check teh all the fuses including efi fuse underhood.
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Sunday, November 11th, 2012 AT 12:22 AM

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