Electrical help! (1 Viewer)

[SmokingRocks]

if you hotwired your fuel pump and heard it running like you said then I am beginning to suspect spark or ECU. Unless the fuel pump is faulty and is failing after start up.

DO THIS NEXT: Test the fuel pump by taking the fuel pressure regulator off of the rail, then thread in a bung with a hose barb on it. Then attach a length of hose and run it into a clear container, secure the hose so it doesn't blow off / out and apply 12v to pin 3 of the F4 connector, this will turn the pump on.

Run the pump for some time, if it doesn't cut out after 15 seconds then we need to look at the ignition ECU side of the equation. DO THIS AND REPORT BACK!

With the pump hotwired it takes the EFI and circuit opening relay out of the equation as you are literally applying 12v to pin 3 of the connector which from there it is just a wire all the way to the pump.

ALSO
Have you checked for engine codes? is your Check Engine Light on?

 

[Alan Jones]

No codes. I just picked up a fuel pump sock and will reinstall shortly. Then I will run your suggested plan and report back. Gotta get the kids in bed first…

How do I PM?

 

[SmokingRocks]

Click my user name then click ‘start conversation’

 

[SmokingRocks]

ALso does the check engine light turn on for ‘bulb check’ when you initially turn the ignition to the ON (not start) position?

 

[Alan Jones]

CEL does come on a ignition. Wired he FP without the pressure regulator and pump ran with no problem. Ran it for a good 30 seconds. FP sock replaced.

 

[Alan Jones]

How would I test the ECU for proper functioning?

 

[Alan Jones]

Does anyone know what sensors have the authority to kill the engine if reading is off? Does the oil pressure sender or the IAC or any others have kill power if reading is out of whack?

 

[blkprj80]

Were, or are, you able to monitor the voltage right at the fuel pump while it's starting and trying to run?

Can you just leave your 12V jumper directly applied to the fuel pump while you're attempting to start it and will it keep running then? Leaving 12V on all the time would be a bad idea, but only for a few minutes should be no issue.

 

[SmokingRocks]

You verified the pump by jumping it, if the engine doesn't stay running when you jump the fuel pump then the fuel pump isn't the issue. Its either a control issue or a Spark Issue. I'm heading off to class right now, let me think about it and I'll get back to you.

 

[SmokingRocks]

Test your crank position sender per the fsm

 

[morganism]

I am over in FJ60 land, but this sounds like the alternator to bottom of fuse box problem that haunts 4Runners. Replace wire with lower gauge.

Be gentle with the connection in the engine compartment, they snap off easily.

Do these engines have an EGR valve ?

 

[SmokingRocks]

It does have an EGR but let's not jump off the diagnosis track we have been on, we have verified the fuel pump is ok. Now we need the focus on the spark / control side.

FACTS:
The alternator was replaced recently and it may have been a faulty unit that sent a voltage spike through the electronics.

I am highly suspect of the alternator having caused damage to the ecu or a sensor such as the crank position sensor.

 

[Alan Jones]

Thank you to all who tried to help problem solve. I went off a hunch and replace the MAF and she fired right up. The MAF checked out per FSM specs, but with a new one in she is driving again. Sorry for all the worries and thank you again for your help.

 

[clx16]

Great News! Just in time for you to use the whole weekend!

 

[morganism]

would still check that wire on bottom of engine compartment fuse block. This will prob happen again if not replaced, it's a metal fatigue issue.

 

[blkprj80]

Glad to hear you found it.
Hopefully it helps someone later who has an issue like yours where the engine will start but won't keep running.


But you still don't know what caused the surge...

 

[Alan Jones]

Not to revive an old issue, but I am getting consistent rough idle when cold and a p0130 and p0133 consistently. Would the consensus be to simply change both sensors? And could all of it be related or just odd timing? Once warm, runs like a champ...