My99

Hey guys. Need some help. I'm trying to help a buddy trouble shoot a starting issue on his 97 Tacoma with a 2.7 engine. The truck is completely stock with about 40-50k miles. We're pretty sure that the fuel pump is not pumping.

The truck has been sitting mostly unused for a few years. It was last started up and driven around about. 6-8 months ago. He went to start it yesterday and it just cranks over. If he sprays carb cleaner in the spark plug wells it fires right up and then dies. I pulled the fuel return line off the fuel rail and had him crank it. No fuel found in the line nor did anything come out during cranking.

Is there a way to test the operation of the fuel pump by jumping some terminals like on my 22RE? Does anyone know if like an old 86 4Runner, does the fuel pump operate only when turning the key to "start" or should it kick on and pressurize with the key "on"?

Where is the ECU located? I found a pinout of the ECU online and it appears PIN 4 in harness E8 is the fuel pump wire. I've read of bad ECUs on these vehicles, so I haven't yet ruled that out.

Thanks for the help!

My99

Anybody?

rworegon

ECU is like located on the passenger side behind the glove box.

You can pull a FSM from the link in my sig. A great help with diagnostics.

My99

Thanks. Yes I checked the FSM. Couldn't find an answer to my questions about triggering the fuel pump by connecting a couple of wires in the diagnostic port. Said either hook a Toyota scan tool to the port or connect directly to the fuel pump leads, which is difficult to do with the tank still bolted up under the truck.

rokblok

iTrader: (1)

Locate the COR and give it a tap. On the 98 Taco my engine came out of, I believe it was to the right of the accelerator pedal, kind of hidden in the console/under dash area. You may also be able to feel/listen to see if it has a "Click" to signify its being told to activate fuel pump. Follow FSM diagram for color codes.

My99

Thanks Rokblok. Can you better describe the "COR"? Is this the relay for the starter? If it is, I do hear a relay clicking when I turn the key to "start" up under the dash. So I suspect that isn't my culprit.

When you say tap it, you mean physically? If it's the relay and you think it's sticking, that makes sense. If it's not the relay, I have no idea what you mean by tap it.

rworegon

COR = Circuit Opening Relay It could be the source of the clicking.

My99

Thanks. Yes, I suspect it is. I kind of assume if it's clicking the relay is working properly. But just in case I'll do a diagnostic on the relay as it outlined.

There's a diagnostic plug (DLC3) under the dash that the FSM instructs can be accessed via the Toyota handheld tester. With this tester you can activate the fuel pump. Does anyone know how, in the absence of this tester to activate the fuel pump from the DLC3?

ThatGuy1295

Put new gas in it silly. Fuel doesnt last 2 years.

My99

Well, he drove it around a few months ago to just start it up and run it and he didn't have any issues. The fact that we can get no confirmation of the pump activating makes us suspect it isn't the gas, although I agree the fuel is far from "good". I pulled the fuel return line and while cranking cannot get anything out of it, also making me think the pump isn't working. Also trying to listen at the fuel tank while cranking yields no audible noise from the pump (2/3 full). Right now I'm really thinking Fuel Pump or ECU.

Another question - anyone have any advice or a picture of the connector (connected) for the fuel pump? I can feel it, but can't seem to get the connector loose up there on the tank.

ThatGuy1295

Well which is it?

My99

6-8. So that's a couple of few months ago. With the other symptoms, I don't believe it to be bad gas at this point.

rokblok

iTrader: (1)

I've had occassionally luck banging on fuel tanks with my fist or a dead blow hammer while someone cranked it over. If the fuel pump is on its way out, sometimes it can stop and not get turning again, but a good knock can jar it a bit and it may start running. Doesn't cost anything... Lol

Mech1003

Green fuel pump relay in dash on left side of steering wheel

2ToyGuy

We called that "percussive trouble shooting" when we did it to my radar systems. I've found that that method pretty much carries over to most any system. Vehicles, radios, you name it, give it a good whack. Can work wonders.

Have fun, all!
Pat☺

Have you tried turning the key to start, without pushing the clutch pedal, or the Clutch Start Cancel button? Tells you quickly whether the fuel pump is running during the start cycle. You should be able to hear the fuel pump running. Engine won't crank, and you won't hurt anything.
If it doesn't run the fuel pump, it could be the "start" side of the COR.

If the COR's start side checks good, you can then check it's "run" side. Simply push the AFM vane open slightly, and turn the key to "on". You should hear the fuel pump running. Again, it could be the AFM, or the COR.
It could also be the wiring back to the fuel pump, or to the COR from the AFM. There's a couple fuses involved, too, IIRC.

Anywho, good luck to you!
Pat☺

My99

Well this thread is a little old, as am I. I guess worth reporting now, as I'm embarrassed I didn't before, the rubber mallet on the bottom of the gas tank while cranking did the trick. The truck is still running and driving with the original pump!

2ToyGuy

You may have percussively repaired the fuel pump's bearings, the power/ground wires, or that kind of thing. You may also have knocked a build-up of crud off the sock on the fuel pump, allowing much more fuel to flow.

You might consider dropping the fuel tank, and getting it cleaned and coated, IF there's a lot of crud and corruption floating around in it.

Anywho, glad you got it going. I hope it keeps on truckin' for long time to come...
Pat☺

My99

Well this truck is in impeccable shape. Not mine but a close friends'. Still probably has less than 80k miles on it. Since this was 9 years ago, I'm gonna say he's going to be okay on this one. I agree - likely just the pump needed a little wake-up tap.